Bitcoin Price Forecast and Analysis – September 19, 2017

Bitcoin (BTC) is once again nearing the all-important $4,000 threshold, a significant bounce-back compared to last week’s low point of $3,200 that came as a result of China’s crackdown on initial coin offerings (ICO).

Of course, the brightest cryptocurrency future has to include the Chinese market and its loads of cash, but for now, Bitcoin should be able to pull itself up steadily back to the $5,000 mark without China’s help.

Cryptocurrencies will need to find a way to reintegrate themselves into the Chinese market in the long term. BTC prices benefit from a surge in.

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Litecoin Price Forecast and Analysis – September 19, 2017

While most of the cryptocurrency market hit the snooze button on Monday, Litecoin traders were up and about. More than $408.0 million worth of LTC coins changed hands as the Litecoin to USD exchange rate jumped roughly 4.11%.

Litecoin also gained around 2.9% against Bitcoin, possibly balancing for the different speeds in their recoveries. Nevertheless, it’ll be a long time before the two currencies are disentangled.

To this day, investors perceive Litecoin as “the silver to Bitcoin’s gold.”

There were moments when the market started to value LTC based on Litecoin news alone (which led to all-time highs), but then China rained on everyone’s parade by shutting down.

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Litecoin Price Forecast and Analysis – September 19, 2017

Ripple Price Forecast and Analysis – September 19, 2017

Ripple prices took a break from the high drama of recent weeks, ending the last 24 hours a slight twitch up to around $0.185670. The stability of the Ripple to USD exchange rate is a constructive signal for investors that grew nervous after the Chinese crackdown.

After all, XRP fell by double digits only a few days ago, putting our annual Ripple price prediction in jeopardy. Cooler heads have prevailed since then, and Ripple is back above where it was a.

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Ripple Price Forecast and Analysis – September 19, 2017

Ripple Price Forecast and Analysis – September 18, 2017

For the first time in a week, cryptocurrencies stuck their heads above water. The Ripple-to-USD exchange rate jumped 7.13% to $0.188622, while simultaneously falling 4.22% against Bitcoin.

China’s ban on cryptocurrency exchanges was once again the biggest piece of Ripple news. This time, however, prices moved to the upside, because investors realized that last week’s reaction was a little excessive (if not downright apocalyptic).

What makes it worse is that Ripple didn’t deserve the beating it took last week.

For one thing, less than five percent of its.

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Ripple Price Forecast and Analysis – September 18, 2017

Litecoin Price Forecast and Analysis – September 18, 2017

Despite China taking a bat to Litecoin’s knees, the Litecoin-to-USD exchange rate bounced up about 9.68% to roughly $51.89. “What explosive piece of Litecoin news caused this rally?” you ask.

Oddly, nothing in particular.

This was a see-saw moment for Litecoin prices. After tilting hard towards the bearish side last week, investors pushed off the bottom to bring LTC prices back above $50.00.

Perhaps they thought the reaction to China’s ban on cryptocurrency exchanges was a tad overblown. Or perhaps they thought LTC is a buy under $50.00.

In either case, the surge in prices is likely to continue now that the fog of uncertainty has lifted.

Last week, we knew nothing.

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Ethereum Price Forecast and Analysis – September 18, 2017

Hallelujah! After a week of non-stop pain, investors finally moved past China’s ban on cryptocurrency exchanges. They bid up prices, bet on fundamentals, and were rewarded with flashing green numbers on their trading monitors.

For instance, the Ethereum-to-USD exchange rate jumped 17% to $280.69 on Sunday.

Considering that it slipped below $200.00 on Friday, the rebound was particularly steep. Who said there’s no resilience in cryptocurrencies? It took less than a week to shrug off China’s ban, which was definitely more than a flesh wound.

Ethereum gained.

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This Cryptocurrency Could Be the Next Bitcoin

Bitcoin Turned $25 into $34 Million
Bitcoin, bitcoin, bitcoin, bitcoin, bitcoin, bitcoin…bitcoin. It’s all that anyone seems to be talking about, yet the volatility of Bitcoin is terrifying. Double-digit swings are a normal occurrence. And no one can explain what it does, at least not in plain English.

But there’s no denying that Bitcoin is a gold mine.

Investors who bought BTC coins in 2013 would have gained 2,411% by now. And those who “mined” the currency made even bigger returns..

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This Cryptocurrency Could Be the Next Bitcoin

Ripple Price Forecast and Analysis – September 15, 2017

As with the rest of the cryptocurrency market, China takes center stage in our Ripple news update. It’s the only thing that matters at the moment, though one could argue that XRP is unfairly caught in the crossfire.

After all, less than five percent of Ripple’s trading volume comes from within China. Add that to the fact that the ban is on trading, and not “blockchain activities,” and it seems like Ripple’s eastward expansion is still on track.

What the regulators objected to was the “disorder” of cryptocurrency exchanges. They aren’t fond of chaos. But.

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Ripple Price Forecast and Analysis – September 15, 2017

Ethereum Price Forecast and Analysis – September 15, 2017

China is the only Ethereum news that matters today, as crypto markets continue to reel from a Chinese crackdown on local exchanges. The entire crypto market is under siege.

Ethereum to USD prices are down about 20.85% and Ethereum to Bitcoin prices dropped roughly 3.1%, suggesting that investors are coalescing around the market leader in times of uncertainty.

With ETH prices touching a two-month low at $201.62, many are wondering when the pain will stop. The truth is, there might be more pain to come.

Two of China’s largest cryptocurrency exchanges have not yet shut.

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Ethereum Price Forecast and Analysis – September 19, 2017

As the dust settles from China’s crackdown on cryptocurrencies, Ethereum looks poised for a rally that could send it across the $300.00 level. However, the situation remains tenuous.

The Chinese ban confirmed the worst fears of some investors—that central banks and other vested interests will regulate against cryptocurrencies to keep their hold on power.

It’s not an unreasonable fear, but I should add that regulators only banned yuan to crypto exchanges, not the existence of blockchain itself. That may sound like a difference without a distinction, but it could be.

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Comet – Wikipedia

A comet is an icy small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred metres to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times the Earth’s diameter, while the tail may stretch one astronomical unit. If sufficiently bright, a comet may be seen from the Earth without the aid of a telescope and may subtend an arc of 30 (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures.

Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several millions of years. Short-period comets originate in the Kuiper belt or its associated scattered disc, which lie beyond the orbit of Neptune. Long-period comets are thought to originate in the Oort cloud, a spherical cloud of icy bodies extending from outside the Kuiper belt to halfway to the nearest star.[1] Long-period comets are set in motion towards the Sun from the Oort cloud by gravitational perturbations caused by passing stars and the galactic tide. Hyperbolic comets may pass once through the inner Solar System before being flung to interstellar space. The appearance of a comet is called an apparition.

Comets are distinguished from asteroids by the presence of an extended, gravitationally unbound atmosphere surrounding their central nucleus. This atmosphere has parts termed the coma (the central part immediately surrounding the nucleus) and the tail (a typically linear section consisting of dust or gas blown out from the coma by the Sun’s light pressure or outstreaming solar wind plasma). However, extinct comets that have passed close to the Sun many times have lost nearly all of their volatile ices and dust and may come to resemble small asteroids.[2] Asteroids are thought to have a different origin from comets, having formed inside the orbit of Jupiter rather than in the outer Solar System.[3][4] The discovery of main-belt comets and active centaur minor planets has blurred the distinction between asteroids and comets.

As of November 2014[update] there are 5,253 known comets,[5] a number that is steadily increasing as they are discovered. However, this represents only a tiny fraction of the total potential comet population, as the reservoir of comet-like bodies in the outer Solar System (in the Oort cloud) is estimated to be one trillion.[6][7] Roughly one comet per year is visible to the naked eye, though many of those are faint and unspectacular.[8] Particularly bright examples are called “Great Comets”. Comets have been visited by unmanned probes such as the European Space Agency’s Rosetta, which became the first ever to land a robotic spacecraft on a comet,[9] and NASA’s Deep Impact, which blasted a crater on Comet Tempel 1 to study its interior.

The word comet derives from the Old English cometa from the Latin comta or comts. That, in turn, is a latinisation of the Greek (“wearing long hair”), and the Oxford English Dictionary notes that the term () already meant “long-haired star, comet” in Greek. was derived from (“to wear the hair long”), which was itself derived from (“the hair of the head”) and was used to mean “the tail of a comet”.[10][11]

The astronomical symbol for comets is (in Unicode U+2604), consisting of a small disc with three hairlike extensions.[12]

The solid, core structure of a comet is known as the nucleus. Cometary nuclei are composed of an amalgamation of rock, dust, water ice, and frozen gases such as carbon dioxide, carbon monoxide, methane, and ammonia.[13] As such, they are popularly described as “dirty snowballs” after Fred Whipple’s model.[14] However, some comets may have a higher dust content, leading them to be called “icy dirtballs”.[15] Research conducted in 2014 suggests that comets are like “deep fried ice cream”, in that their surfaces are formed of dense crystalline ice mixed with organic compounds, while the interior ice is colder and less dense.[16]

The surface of the nucleus is generally dry, dusty or rocky, suggesting that the ices are hidden beneath a surface crust several metres thick. In addition to the gases already mentioned, the nuclei contain a variety of organic compounds, which may include methanol, hydrogen cyanide, formaldehyde, ethanol, and ethane and perhaps more complex molecules such as long-chain hydrocarbons and amino acids.[17][18] In 2009, it was confirmed that the amino acid glycine had been found in the comet dust recovered by NASA’s Stardust mission.[19] In August 2011, a report, based on NASA studies of meteorites found on Earth, was published suggesting DNA and RNA components (adenine, guanine, and related organic molecules) may have been formed on asteroids and comets.[20][21]

The outer surfaces of cometary nuclei have a very low albedo, making them among the least reflective objects found in the Solar System. The Giotto space probe found that the nucleus of Halley’s Comet reflects about four percent of the light that falls on it,[22] and Deep Space 1 discovered that Comet Borrelly’s surface reflects less than 3.0% of the light that falls on it;[22] by comparison, asphalt reflects seven percent. The dark surface material of the nucleus may consist of complex organic compounds. Solar heating drives off lighter volatile compounds, leaving behind larger organic compounds that tend to be very dark, like tar or crude oil. The low reflectivity of cometary surfaces causes them to absorb the heat that drives their outgassing processes.[23]

Comet nuclei with radii of up to 30 kilometres (19mi) have been observed,[24] but ascertaining their exact size is difficult.[25] The nucleus of 322P/SOHO is probably only 100200 metres (330660ft) in diameter.[26] A lack of smaller comets being detected despite the increased sensitivity of instruments has led some to suggest that there is a real lack of comets smaller than 100 metres (330ft) across.[27] Known comets have been estimated to have an average density of 0.6g/cm3 (0.35oz/cuin).[28] Because of their low mass, comet nuclei do not become spherical under their own gravity and therefore have irregular shapes.[29]

Roughly six percent of the near-Earth asteroids are thought to be extinct nuclei of comets that no longer experience outgassing,[30] including 14827 Hypnos and 3552 Don Quixote.

Results from the Rosetta and Philae spacecraft show that the nucleus of 67P/ChuryumovGerasimenko has no magnetic field, which suggests that magnetism may not have played a role in the early formation of planetesimals.[31][32] Further, the ALICE spectrograph on Rosetta determined that electrons (within 1km (0.62mi) above the comet nucleus) produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought earlier, are responsible for the degradation of water and carbon dioxide molecules released from the comet nucleus into its coma.[33][34] Instruments on the Philae lander found at least sixteen organic compounds at the comet’s surface, four of which (acetamide, acetone, methyl isocyanate and propionaldehyde) have been detected for the first time on a comet.[35][36][37]

The streams of dust and gas thus released form a huge and extremely thin atmosphere around the comet called the “coma”. The force exerted on the coma by the Sun’s radiation pressure and solar wind cause an enormous “tail” to form pointing away from the Sun.[46]

The coma is generally made of H2O and dust, with water making up to 90% of the volatiles that outflow from the nucleus when the comet is within 3 to 4 astronomical units (450,000,000 to 600,000,000km; 280,000,000 to 370,000,000mi) of the Sun.[47] The H2O parent molecule is destroyed primarily through photodissociation and to a much smaller extent photoionization, with the solar wind playing a minor role in the destruction of water compared to photochemistry.[47] Larger dust particles are left along the comet’s orbital path whereas smaller particles are pushed away from the Sun into the comet’s tail by light pressure.[48]

Although the solid nucleus of comets is generally less than 60 kilometres (37mi) across, the coma may be thousands or millions of kilometres across, sometimes becoming larger than the Sun.[49] For example, about a month after an outburst in October 2007, comet 17P/Holmes briefly had a tenuous dust atmosphere larger than the Sun.[50] The Great Comet of 1811 also had a coma roughly the diameter of the Sun.[51] Even though the coma can become quite large, its size can decrease about the time it crosses the orbit of Mars around 1.5 astronomical units (220,000,000km; 140,000,000mi) from the Sun.[51] At this distance the solar wind becomes strong enough to blow the gas and dust away from the coma, and in doing so enlarging the tail.[51] Ion tails have been observed to extend one astronomical unit (150 million km) or more.[50]

Both the coma and tail are illuminated by the Sun and may become visible when a comet passes through the inner Solar System, the dust reflects Sunlight directly while the gases glow from ionisation.[52] Most comets are too faint to be visible without the aid of a telescope, but a few each decade become bright enough to be visible to the naked eye.[53] Occasionally a comet may experience a huge and sudden outburst of gas and dust, during which the size of the coma greatly increases for a period of time. This happened in 2007 to Comet Holmes.[54]

In 1996, comets were found to emit X-rays.[55] This greatly surprised astronomers because X-ray emission is usually associated with very high-temperature bodies. The X-rays are generated by the interaction between comets and the solar wind: when highly charged solar wind ions fly through a cometary atmosphere, they collide with cometary atoms and molecules, “stealing” one or more electrons from the atom in a process called “charge exchange”. This exchange or transfer of an electron to the solar wind ion is followed by its de-excitation into the ground state of the ion by the emission of X-rays and far ultraviolet photons.[56]

In the outer Solar System, comets remain frozen and inactive and are extremely difficult or impossible to detect from Earth due to their small size. Statistical detections of inactive comet nuclei in the Kuiper belt have been reported from observations by the Hubble Space Telescope[57][58] but these detections have been questioned.[59][60] As a comet approaches the inner Solar System, solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them.

The streams of dust and gas each form their own distinct tail, pointing in slightly different directions. The tail of dust is left behind in the comet’s orbit in such a manner that it often forms a curved tail called the type II or dust tail.[52] At the same time, the ion or type I tail, made of gases, always points directly away from the Sun because this gas is more strongly affected by the solar wind than is dust, following magnetic field lines rather than an orbital trajectory.[61] On occasions – such as when the Earth passes through a comet’s orbital plane, a tail pointing in the opposite direction to the ion and dust tails called the antitail may be seen.[62]

The observation of antitails contributed significantly to the discovery of solar wind.[63] The ion tail is formed as a result of the ionisation by solar ultra-violet radiation of particles in the coma. Once the particles have been ionized, they attain a net positive electrical charge, which in turn gives rise to an “induced magnetosphere” around the comet. The comet and its induced magnetic field form an obstacle to outward flowing solar wind particles. Because the relative orbital speed of the comet and the solar wind is supersonic, a bow shock is formed upstream of the comet in the flow direction of the solar wind. In this bow shock, large concentrations of cometary ions (called “pick-up ions”) congregate and act to “load” the solar magnetic field with plasma, such that the field lines “drape” around the comet forming the ion tail.[64]

If the ion tail loading is sufficient, the magnetic field lines are squeezed together to the point where, at some distance along the ion tail, magnetic reconnection occurs. This leads to a “tail disconnection event”.[64] This has been observed on a number of occasions, one notable event being recorded on 20 April 2007, when the ion tail of Encke’s Comet was completely severed while the comet passed through a coronal mass ejection. This event was observed by the STEREO space probe.[65]

In 2013, ESA scientists reported that the ionosphere of the planet Venus streams outwards in a manner similar to the ion tail seen streaming from a comet under similar conditions.”[66][67]

Uneven heating can cause newly generated gases to break out of a weak spot on the surface of comet’s nucleus, like a geyser.[68] These streams of gas and dust can cause the nucleus to spin, and even split apart.[68] In 2010 it was revealed dry ice (frozen carbon dioxide) can power jets of material flowing out of a comet nucleus.[69] Infrared imaging of Hartley 2 shows such jets exiting and carrying with it dust grains into the coma.[70]

Most comets are small Solar System bodies with elongated elliptical orbits that take them close to the Sun for a part of their orbit and then out into the further reaches of the Solar System for the remainder.[71] Comets are often classified according to the length of their orbital periods: The longer the period the more elongated the ellipse.

Periodic comets or short-period comets are generally defined as those having orbital periods of less than 200 years.[72] They usually orbit more-or-less in the ecliptic plane in the same direction as the planets.[73] Their orbits typically take them out to the region of the outer planets (Jupiter and beyond) at aphelion; for example, the aphelion of Halley’s Comet is a little beyond the orbit of Neptune. Comets whose aphelia are near a major planet’s orbit are called its “family”.[74] Such families are thought to arise from the planet capturing formerly long-period comets into shorter orbits.[75]

At the shorter orbital period extreme, Encke’s Comet has an orbit that does not reach the orbit of Jupiter, and is known as an Encke-type comet. Short-period comets with orbital periods less than 20 years and low inclinations (up to 30 degrees) to the ecliptic are called Jupiter-family comets (JFCs).[76][77] Those like Halley, with orbital periods of between 20 and 200 years and inclinations extending from zero to more than 90 degrees, are called Halley-type comets (HTCs).[78][79] As of 2017[update], only 87 HTCs have been observed, compared with 567 identified JFCs.[80]

Recently discovered main-belt comets form a distinct class, orbiting in more circular orbits within the asteroid belt.[81]

Because their elliptical orbits frequently take them close to the giant planets, comets are subject to further gravitational perturbations.[82] Short-period comets have a tendency for their aphelia to coincide with a giant planet’s semi-major axis, with the JFCs being the largest group.[77] It is clear that comets coming in from the Oort cloud often have their orbits strongly influenced by the gravity of giant planets as a result of a close encounter. Jupiter is the source of the greatest perturbations, being more than twice as massive as all the other planets combined. These perturbations can deflect long-period comets into shorter orbital periods.[83][84]

Based on their orbital characteristics, short-period comets are thought to originate from the centaurs and the Kuiper belt/scattered disc[85] a disk of objects in the trans-Neptunian regionwhereas the source of long-period comets is thought to be the far more distant spherical Oort cloud (after the Dutch astronomer Jan Hendrik Oort who hypothesised its existence).[86] Vast swarms of comet-like bodies are thought to orbit the Sun in these distant regions in roughly circular orbits. Occasionally the gravitational influence of the outer planets (in the case of Kuiper belt objects) or nearby stars (in the case of Oort cloud objects) may throw one of these bodies into an elliptical orbit that takes it inwards toward the Sun to form a visible comet. Unlike the return of periodic comets, whose orbits have been established by previous observations, the appearance of new comets by this mechanism is unpredictable.[87]

Long-period comets have highly eccentric orbits and periods ranging from 200 years to thousands of years.[88] An eccentricity greater than 1 when near perihelion does not necessarily mean that a comet will leave the Solar System.[89] For example, Comet McNaught had a heliocentric osculating eccentricity of 1.000019 near its perihelion passage epoch in January 2007 but is bound to the Sun with roughly a 92,600-year orbit because the eccentricity drops below 1 as it moves further from the Sun. The future orbit of a long-period comet is properly obtained when the osculating orbit is computed at an epoch after leaving the planetary region and is calculated with respect to the center of mass of the Solar System. By definition long-period comets remain gravitationally bound to the Sun; those comets that are ejected from the Solar System due to close passes by major planets are no longer properly considered as having “periods”. The orbits of long-period comets take them far beyond the outer planets at aphelia, and the plane of their orbits need not lie near the ecliptic. Long-period comets such as Comet West and C/1999 F1 can have aphelion distances of nearly 70,000 AU with orbital periods estimated around 6 million years.

Single-apparition or non-periodic comets are similar to long-period comets because they also have parabolic or slightly hyperbolic trajectories[88] when near perihelion in the inner Solar System. However, gravitational perturbations from giant planets cause their orbits to change. Single-apparition comets have a hyperbolic or parabolic osculating orbit which allows them to permanently exit the Solar System after a single pass of the Sun.[90] The Sun’s Hill sphere has an unstable maximum boundary of 230,000 AU (1.1 parsecs (3.6 light-years)).[91] Only a few hundred comets have been seen to reach a hyperbolic orbit (e > 1) when near perihelion[92] that using a heliocentric unperturbed two-body best-fit suggests they may escape the Solar System.

No comets with an eccentricity significantly greater than one have been observed,[92] so there are no confirmed observations of comets that are likely to have originated outside the Solar System. Comet C/1980 E1 had an orbital period of roughly 7.1 million years before the 1982 perihelion passage, but a 1980 encounter with Jupiter accelerated the comet giving it the largest eccentricity (1.057) of any known hyperbolic comet.[93] Comets not expected to return to the inner Solar System include C/1980 E1, C/2000 U5, C/2001 Q4 (NEAT), C/2009 R1, C/1956 R1, and C/2007 F1 (LONEOS).

Some authorities use the term “periodic comet” to refer to any comet with a periodic orbit (that is, all short-period comets plus all long-period comets),[94] whereas others use it to mean exclusively short-period comets.[88] Similarly, although the literal meaning of “non-periodic comet” is the same as “single-apparition comet”, some use it to mean all comets that are not “periodic” in the second sense (that is, to also include all comets with a period greater than 200 years).

Early observations have revealed a few genuinely hyperbolic (i.e. non-periodic) trajectories, but no more than could be accounted for by perturbations from Jupiter. If comets pervaded interstellar space, they would be moving with velocities of the same order as the relative velocities of stars near the Sun (a few tens of km per second). If such objects entered the Solar System, they would have positive specific orbital energy and would be observed to have genuinely hyperbolic trajectories. A rough calculation shows that there might be four hyperbolic comets per century within Jupiter’s orbit, give or take one and perhaps two orders of magnitude.[95]

The Oort cloud is thought to occupy a vast space starting from between 2,000 and 5,000AU (0.03 and 0.08ly)[97] to as far as 50,000AU (0.79ly)[78] from the Sun. Some estimates place the outer edge at between 100,000 and 200,000AU (1.58 and 3.16ly).[97] The region can be subdivided into a spherical outer Oort cloud of 20,00050,000AU (0.320.79ly), and a doughnut-shaped inner cloud, the Hills cloud, of 2,00020,000AU (0.030.32ly).[98] The outer cloud is only weakly bound to the Sun and supplies the long-period (and possibly Halley-type) comets that fall to inside the orbit of Neptune.[78] The inner Oort cloud is also known as the Hills cloud, named after J. G. Hills, who proposed its existence in 1981.[99] Models predict that the inner cloud should have tens or hundreds of times as many cometary nuclei as the outer halo;[99][100][101] it is seen as a possible source of new comets that resupply the relatively tenuous outer cloud as the latter’s numbers are gradually depleted. The Hills cloud explains the continued existence of the Oort cloud after billions of years.[102]

Exocomets beyond the Solar System have also been detected and may be common in the Milky Way.[103] The first exocomet system detected was around Beta Pictoris, a very young A-type main-sequence star, in 1987.[104][105] A total of 10 such exocomet systems have been identified as of 2013[update], using the absorption spectrum caused by the large clouds of gas emitted by comets when passing close to their star.[103][104]

As a result of outgassing, comets leave in their wake a trail of solid debris too large to be swept away by radiation pressure and the solar wind.[106] If the Earth’s orbit sends it though that debris, there are likely to be meteor showers as Earth passes through. The Perseid meteor shower, for example, occurs every year between 9 and 13 August, when Earth passes through the orbit of Comet SwiftTuttle.[107]Halley’s Comet is the source of the Orionid shower in October.[107]

Many comets and asteroids collided with Earth in its early stages. Many scientists think that comets bombarding the young Earth about 4 billion years ago brought the vast quantities of water that now fill the Earth’s oceans, or at least a significant portion of it. Others have cast doubt on this idea.[108] The detection of organic molecules, including polycyclic aromatic hydrocarbons,[16] in significant quantities in comets has led to speculation that comets or meteorites may have brought the precursors of lifeor even life itselfto Earth.[109] In 2013 it was suggested that impacts between rocky and icy surfaces, such as comets, had the potential to create the amino acids that make up proteins through shock synthesis.[110] In 2015, scientists found significant amounts of molecular oxygen in the outgassings of comet 67P, suggesting that the molecule may occur more often than had been thought, and thus less an indicator of life as has been supposed.[111]

It is suspected that comet impacts have, over long timescales, also delivered significant quantities of water to the Earth’s Moon, some of which may have survived as lunar ice.[112] Comet and meteoroid impacts are also thought to be responsible for the existence of tektites and australites.[113]

If a comet is traveling fast enough, it may leave the Solar System. Such comets follow the open path of a hyperbola, and as such they are called hyperbolic comets. To date, comets are only known to be ejected by interacting with another object in the Solar System, such as Jupiter.[114] An example of this is thought to be Comet C/1980 E1, which was shifted from a predicted orbit of 7.1 million years around the Sun, to a hyperbolic trajectory, after a 1980 close pass by the planet Jupiter.[115]

Jupiter-family comets and long-period comets appear to follow very different fading laws. The JFCs are active over a lifetime of about 10,000 years or ~1,000 orbits whereas long-period comets fade much faster. Only 10% of the long-period comets survive more than 50 passages to small perihelion and only 1% of them survive more than 2,000 passages.[30] Eventually most of the volatile material contained in a comet nucleus evaporates, and the comet becomes a small, dark, inert lump of rock or rubble that can resemble an asteroid.[116] Some asteroids in elliptical orbits are now identified as extinct comets.[117] Roughly six percent of the near-Earth asteroids are thought to be extinct comet nuclei.[30]

The nucleus of some comets may be fragile, a conclusion supported by the observation of comets splitting apart.[118] A significant cometary disruption was that of Comet ShoemakerLevy 9, which was discovered in 1993. A close encounter in July 1992 had broken it into pieces, and over a period of six days in July 1994, these pieces fell into Jupiter’s atmospherethe first time astronomers had observed a collision between two objects in the Solar System.[119][120] Other splitting comets include 3D/Biela in 1846 and 73P/SchwassmannWachmann from 1995 to 2006.[121] Greek historian Ephorus reported that a comet split apart as far back as the winter of 372373 BC.[122] Comets are suspected of splitting due to thermal stress, internal gas pressure, or impact.[123]

Comets 42P/Neujmin and 53P/Van Biesbroeck appear to be fragments of a parent comet. Numerical integrations have shown that both comets had a rather close approach to Jupiter in January 1850, and that, before 1850, the two orbits were nearly identical.[124]

Some comets have been observed to break up during their perihelion passage, including great comets West and IkeyaSeki. Biela’s Comet was one significant example, when it broke into two pieces during its passage through the perihelion in 1846. These two comets were seen separately in 1852, but never again afterward. Instead, spectacular meteor showers were seen in 1872 and 1885 when the comet should have been visible. A minor meteor shower, the Andromedids, occurs annually in November, and it is caused when the Earth crosses the orbit of Biela’s Comet.[125]

Some comets meet a more spectacular end either falling into the Sun[126] or smashing into a planet or other body. Collisions between comets and planets or moons were common in the early Solar System: some of the many craters on the Moon, for example, may have been caused by comets. A recent collision of a comet with a planet occurred in July 1994 when Comet ShoemakerLevy 9 broke up into pieces and collided with Jupiter.[127]

Ghost tail of C/2015 D1 (SOHO) after passage at the sun

The names given to comets have followed several different conventions over the past two centuries. Prior to the early 20th century, most comets were simply referred to by the year when they appeared, sometimes with additional adjectives for particularly bright comets; thus, the “Great Comet of 1680”, the “Great Comet of 1882”, and the “Great January Comet of 1910”.

After Edmund Halley demonstrated that the comets of 1531, 1607, and 1682 were the same body and successfully predicted its return in 1759 by calculating its orbit, that comet became known as Halley’s Comet.[129] Similarly, the second and third known periodic comets, Encke’s Comet[130] and Biela’s Comet,[131] were named after the astronomers who calculated their orbits rather than their original discoverers. Later, periodic comets were usually named after their discoverers, but comets that had appeared only once continued to be referred to by the year of their appearance.[132]

In the early 20th century, the convention of naming comets after their discoverers became common, and this remains so today. A comet can be named after its discoverers, or an instrument or program that helped to find it.[132]

From ancient sources, such as Chinese oracle bones, it is known that their appearances have been noticed by humans for millennia.[133] Until the sixteenth century, comets were usually considered bad omens of deaths of kings or noble men, or coming catastrophes, or even interpreted as attacks by heavenly beings against terrestrial inhabitants.[134][135]

Aristotle believed that comets were atmospheric phenomena, due to the fact that they could appear outside of the Zodiac and vary in brightness over the course of a few days.[136]Pliny the Elder believed that comets were connected with political unrest and death.[137]

In India, by the 6th century astronomers believed that comets were celestial bodies that re-appeared periodically. This was the view expressed in the 6th century by the astronomers Varhamihira and Bhadrabahu, and the 10th-century astronomer Bhaotpala listed the names and estimated periods of certain comets, but it is not known how these figures were calculated or how accurate they were.[138]

In the 16th century Tycho Brahe demonstrated that comets must exist outside the Earth’s atmosphere by measuring the parallax of the Great Comet of 1577 from observations collected by geographically separated observers. Within the precision of the measurements, this implied the comet must be at least four times more distant than from the Earth to the Moon.[139][140]

Isaac Newton, in his Principia Mathematica of 1687, proved that an object moving under the influence of gravity must trace out an orbit shaped like one of the conic sections, and he demonstrated how to fit a comet’s path through the sky to a parabolic orbit, using the comet of 1680 as an example.[141]

In 1705, Edmond Halley (16561742) applied Newton’s method to twenty-three cometary apparitions that had occurred between 1337 and 1698. He noted that three of these, the comets of 1531, 1607, and 1682, had very similar orbital elements, and he was further able to account for the slight differences in their orbits in terms of gravitational perturbation caused by Jupiter and Saturn. Confident that these three apparitions had been three appearances of the same comet, he predicted that it would appear again in 17589.[142] Halley’s predicted return date was later refined by a team of three French mathematicians: Alexis Clairaut, Joseph Lalande, and Nicole-Reine Lepaute, who predicted the date of the comet’s 1759 perihelion to within one month’s accuracy.[143][144] When the comet returned as predicted, it became known as Halley’s Comet (with the latter-day designation of 1P/Halley). It will next appear in 2061.[145]

From his huge vapouring train perhaps to shake Reviving moisture on the numerous orbs, Thro’ which his long ellipsis winds; perhaps To lend new fuel to declining suns, To light up worlds, and feed th’ ethereal fire.

Isaac Newton described comets as compact and durable solid bodies moving in oblique orbit and their tails as thin streams of vapor emitted by their nuclei, ignited or heated by the Sun. Newton suspected that comets were the origin of the life-supporting component of air.[147]

As early as the 18th century, some scientists had made correct hypotheses as to comets’ physical composition. In 1755, Immanuel Kant hypothesized that comets are composed of some volatile substance, whose vaporization gives rise to their brilliant displays near perihelion.[148] In 1836, the German mathematician Friedrich Wilhelm Bessel, after observing streams of vapor during the appearance of Halley’s Comet in 1835, proposed that the jet forces of evaporating material could be great enough to significantly alter a comet’s orbit, and he argued that the non-gravitational movements of Encke’s Comet resulted from this phenomenon.[149]

In 1950, Fred Lawrence Whipple proposed that rather than being rocky objects containing some ice, comets were icy objects containing some dust and rock.[150] This “dirty snowball” model soon became accepted and appeared to be supported by the observations of an armada of spacecraft (including the European Space Agency’s Giotto probe and the Soviet Union’s Vega 1 and Vega 2) that flew through the coma of Halley’s Comet in 1986, photographed the nucleus, and observed jets of evaporating material.[151]

On 22 January 2014, ESA scientists reported the detection, for the first definitive time, of water vapor on the dwarf planet Ceres, the largest object in the asteroid belt.[152] The detection was made by using the far-infrared abilities of the Herschel Space Observatory.[153] The finding is unexpected because comets, not asteroids, are typically considered to “sprout jets and plumes”. According to one of the scientists, “The lines are becoming more and more blurred between comets and asteroids.”[153] On 11 August 2014, astronomers released studies, using the Atacama Large Millimeter/Submillimeter Array (ALMA) for the first time, that detailed the distribution of HCN, HNC, H 2CO, and dust inside the comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON).[154][155]

Approximately once a decade, a comet becomes bright enough to be noticed by a casual observer, leading such comets to be designated as great comets.[122] Predicting whether a comet will become a great comet is notoriously difficult, as many factors may cause a comet’s brightness to depart drastically from predictions.[164] Broadly speaking, if a comet has a large and active nucleus, will pass close to the Sun, and is not obscured by the Sun as seen from the Earth when at its brightest, it has a chance of becoming a great comet. However, Comet Kohoutek in 1973 fulfilled all the criteria and was expected to become spectacular but failed to do so.[165]Comet West, which appeared three years later, had much lower expectations but became an extremely impressive comet.[166]

The late 20th century saw a lengthy gap without the appearance of any great comets, followed by the arrival of two in quick successionComet Hyakutake in 1996, followed by HaleBopp, which reached maximum brightness in 1997 having been discovered two years earlier. The first great comet of the 21st century was C/2006 P1 (McNaught), which became visible to naked eye observers in January 2007. It was the brightest in over 40 years.[167]

A sungrazing comet is a comet that passes extremely close to the Sun at perihelion, generally within a few million kilometres.[168] Although small sungrazers can be completely evaporated during such a close approach to the Sun, larger sungrazers can survive many perihelion passages. However, the strong tidal forces they experience often lead to their fragmentation.[169]

About 90% of the sungrazers observed with SOHO are members of the Kreutz group, which all originate from one giant comet that broke up into many smaller comets during its first passage through the inner Solar System.[170] The remainder contains some sporadic sungrazers, but four other related groups of comets have been identified among them: the Kracht, Kracht 2a, Marsden, and Meyer groups. The Marsden and Kracht groups both appear to be related to Comet 96P/Machholz, which is also the parent of two meteor streams, the Quadrantids and the Arietids.[171]

Of the thousands of known comets, some exhibit unusual properties. Comet Encke (2P/Encke) orbits from outside the asteroid belt to just inside the orbit of the planet Mercury whereas the Comet 29P/SchwassmannWachmann currently travels in a nearly circular orbit entirely between the orbits of Jupiter and Saturn.[172]2060 Chiron, whose unstable orbit is between Saturn and Uranus, was originally classified as an asteroid until a faint coma was noticed.[173] Similarly, Comet ShoemakerLevy 2 was originally designated asteroid 1990 UL3.[174](See also Fate of comets, above)

Centaurs typically behave with characteristics of both asteroids and comets.[175] Centaurs can be classified as comets such as 60558 Echeclus, and 166P/NEAT. 166P/NEAT was discovered while it exhibited a coma, and so is classified as a comet despite its orbit, and 60558 Echeclus was discovered without a coma but later became active,[176] and was then classified as both a comet and an asteroid (174P/Echeclus). One plan for Cassini involved sending it to a centaur, but NASA decided to destroy it instead.[177]

A comet may be discovered photographically using a wide-field telescope or visually with binoculars. However, even without access to optical equipment, it is still possible for the amateur astronomer to discover a sungrazing comet online by downloading images accumulated by some satellite observatories such as SOHO.[178] SOHO’s 2000th comet was discovered by Polish amateur astronomer Micha Kusiak on 26 December 2010[179] and both discoverers of Hale-Bopp used amateur equipment (although Hale was not an amateur).

A number of periodic comets discovered in earlier decades or previous centuries are now lost comets. Their orbits were never known well enough to predict future appearances or the comets have disintegrated. However, occasionally a “new” comet is discovered, and calculation of its orbit shows it to be an old “lost” comet. An example is Comet 11P/TempelSwiftLINEAR, discovered in 1869 but unobservable after 1908 because of perturbations by Jupiter. It was not found again until accidentally rediscovered by LINEAR in 2001.[180] There are at least 18 comets that fit this category.[181]

NASA is developing a comet harpoon for returning samples to Earth.

The depiction of comets in popular culture is firmly rooted in the long Western tradition of seeing comets as harbingers of doom and as omens of world-altering change.[183] Halley’s Comet alone has caused a slew of sensationalist publications of all sorts at each of its reappearances. It was especially noted that the birth and death of some notable persons coincided with separate appearances of the comet, such as with writers Mark Twain (who correctly speculated that he’d “go out with the comet” in 1910)[183] and Eudora Welty, to whose life Mary Chapin Carpenter dedicated the song “Halley Came to Jackson”.[183]

In times past, bright comets often inspired panic and hysteria in the general population, being thought of as bad omens. More recently, during the passage of Halley’s Comet in 1910, the Earth passed through the comet’s tail, and erroneous newspaper reports inspired a fear that cyanogen in the tail might poison millions,[184] whereas the appearance of Comet HaleBopp in 1997 triggered the mass suicide of the Heaven’s Gate cult.[185]

In science fiction, the impact of comets has been depicted as a threat overcome by technology and heroism (as in the 1998 films Deep Impact and Armageddon), or as a trigger of global apocalypse (Lucifer’s Hammer, 1979) or zombies (Night of the Comet, 1984).[183] In Jules Verne’s Off on a Comet a group of people are stranded on a comet orbiting the Sun, while a large manned space expedition visits Halley’s Comet in Sir Arthur C. Clarke’s novel 2061: Odyssey Three.[186]

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Comet – Wikipedia

Comet Facts – Interesting Facts about Comets – Space Facts

Comet ISON stardustobservatory.org/images.php?page=details&id=363

A comet is a very small solar system body made mostly of ices mixed with smaller amounts of dust and rock. Most comets are no larger than a few kilometres across. The main body of the comet is called the nucleus, and it can contain water, methane, nitrogen and other ices.

When a comet is heated by the Sun, its ices begin to sublimate (similar to the way dry ice fizzes when you leave it in sunlight). The mixture of ice crystals and dust blows away from the comet nucleus in the solar wind, creating a pair of tails. The dust tail is what we normally see when we view comets from Earth.

A plasma tail also forms when molecules of gas are excited by interaction with the solar wind. The plasma tail is not normally seen with the naked eye, but can be imaged. Comets normally orbit the Sun, and have their origins in the Oort Cloud and Kuiper Belt regions of the outer solar system.

There are many misconceptions about comets, which are simply pieces of solar system ices travelling in orbit around the Sun. Here are some fascinating and true facts about comets.

Comets come in several categories. The most common are periodic and non-periodic.

In the past, comets were named for their discoverers, such as Comet Halley for Sir Edmond Halley. In modern times, comet names are governed by rules set forth by the International Astronomical Union (IAU). A comet is given an official designation, and can also be identified by the last names of up to three independent discoverers.

Heres how it works. Once a comet has been confirmed, the following naming rules are followed. First, if the comet is a periodic comet, then it is indicated with a P/ followed by the year of its discovery, a letter indicating the half-month in which it was discovered, followed by a number indicating its order of discovery. So, for example, the second periodic comet found in the first half of January, 2015 would be called P/2015 A2.

A non-periodic comet would be indicated with a C/ followed by the year of its discovery, a letter indicating the half-month in which it was discovered, followed by a number indicating its order of discovery.

If a comet is independently discovered by three people named Smith, Jones, and Petersen, it could also be called Comet Smith-Jones-Petersen, in addition to its formal designation. Today, many comets are found through automated instrument searches, and so the formal designations are more commonly used.

Well-known comets include the non-periodic comets Hale-Bopp (C/1995 O1), Hyakutake (C/1996 B2), McNaught (C2006 P1), and Lovejoy (C/2011 W3). These flared brightly in our skies and then faded into obscurity.

In addition, Comet Shoemaker-Levy 9 (D/1993 F2) was spotted after it had broken up after a close call with Jupiter. (The D in its proper designation means it has disappeared or is determined to no longer exist). More than a year later, the pieces of the comet crashed into Jupiter.

The periodic Comet Halley (1P/Halley) is the most famous in history. It returns to the inner solar system once every 76 years. Other well-known periodic comets include 2P/Encke, which appears ever 3.3 years and 9P/Tempel (Tempel 2), which was visited by the Deep Impact and Stardust probes, and makes perihelion around the Sun every 5.5 years.

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Comet Facts – Interesting Facts about Comets – Space Facts

Comets to play Crunch in preseason game in Rome – Times Telegram – The Times Telegram

Ben Birnell

The Utica Comets are set to return to a familiar place in the Mohawk Valley for a preseason game.

Their opponent also is well-known to hockey fans in Central New York.

The Comets announced Thursday the team will host the rival Syracuse Crunch at 5 p.m. Saturday, Sept. 30, at Kennedy Arena in Rome to begin out a home-and-home exhibition series.

Tickets are $10 and will go on sale at 2 p.m. Friday, Sept. 8, at the Kennedy Arena box office.A special Season Ticket member presale will begin at 10 a.m.All proceeds will go to Kennedy Arena.

The preseason game is being played in Rome because of the construction project at Utica Memorial Auditorium. The contest will mark the third time since the Comets began play in 2013 that the team will have a preseason game at the Rome rink. The Comets played preseason contests in Rome in 2013 and 2014.

I like Kennedy Arena, Comets president Rob Esche said. “Im happy we were able to work … with the city of Rome and the AHL to highlight such a great hockey community, and to kick off what is to be a very special fifth anniversary season.

This will be the third consecutive preseason that the Comets have taken on Syracuse, which is Tampa Bay Lightnings top affiliate. Last season, a home-and-home series between teams included a game at the Aud. In 2015, the teams traveled to France for training camp and preseason.

The teams will close out the preseason series at 5 p.m. Sunday, Oct. 1, at War Memorial arena in Syracuse. Including the regular season, the North Division foes will meet a total of 14 times in 2017-18. This season, the series has some added intrigue as new Comets coach Trent Cull and associate coach Gary Agnew previously were coaches at different times with Syracuse.

The Comets open the regular season the first full weekend of October. Utica travels to North Division rival Toronto for a two-game set on Saturday, Oct. 7, and Sunday, Oct. 8. Both games are set for 3 p.m. starts. It is the first of seven consecutive road games for the Comets to start the season.

Cometssign goaltender

The Utica Comets signed goaltender Michael Garteigto a one-year American Hockey League contract,general manager Ryan Johnson announced Thursday.

Garteig appeared in eight games with the Comets last season. He went 0-4-1 with a .897 save percentage and a 3.01 goals against average in net for Utica.

The 25-year-old British Columbia native and former Quinnipiac University skater posted an 11-6-2 record for the Alaska Aces last season in the ECHL.Standing at6-foot-1, 183-pound, Garteig dressed in 22 games for Alaska, recording a .906 save percentage and a 3.11 goals against average.

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Comets to play Crunch in preseason game in Rome – Times Telegram – The Times Telegram

Comets win opener – Waupaca County News

August 24, 2017

Medford’s Sam Hallgren (left) collides with Waupaca’s Jack Snider during the second half of a nonconference boys’ soccer game at Waupaca High School. Greg Seubert Photo

By Greg Seubert

Waupacas boys soccer team opened its season with a win.

Jack Sniders goal broke a 1-1 tie and the Comets went on to hand Medford a 2-1 nonconference loss Aug. 22 in the season opener for both teams.

Damian Johnson gave Waupaca a 1-0 lead in the 34th minute off of an assist from Keenin Polebitski and Matt Marquette.

Medford tied the game in the 68th minute on a goal from Alex Veal, but Snider found the net for the game-winning goal two minutes later.

Passing was excellent today, coach Cory Nagel said. Great looks and finding the open man. Medford played an excellent offsides trap, which frustrated our forwards most of the game. Dawson Patzke, a freshman, played the entire game in his first-ever high school soccer game. It wont show up on the stat sheet, but he was our rock today.

Bailey Colden had 10 saves in goal.

Waupaca will play its first game at Comet Field at 6:30 p.m. Thursday, Aug. 31, as the Comets host Wrightstown in the North Eastern Conference opener.

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Comets win opener – Waupaca County News

Comets spikers down Dan River High School 3-1 in opening game – YourGV.com

The Halifax County High School varsity volleyball team got its season off to a good start Tuesday night with a 3-1 win over Dan River High School at Dan River High School in Ringgold.

Dan River High School topped the Comets 25-19 in the opening game, but the Comets bounced back to win three games in a row by scores of 25-13, 25-16 and 25-18 to win the best-of-five-game match.

Overall it was a great first game and a good win, said Comets Head Coach Tiffaney Bratton.

We saw that we needed to work on some things to compete in our district and beyond. The girls had a great time on the court and came home with a win.

The Comets struggled with service errors at times in the opening game, opening the door for Dan River High School to pull off the win.

We missed key serves in the first game that cost us that one, Bratton explained.

We controlled the ball well in the first game. but we made some small mistakes that cost at critical moments. We also let some balls drop without making a play on them.

The Comets bounced back with a better effort in the second game, improving their ability to place their shots.

The team played much smarter in the second game, Bratton pointed out.

They figured out that if they controlled the ball more on our side we could put the ball in spots that Dan River couldnt return it.

The Comets continued to control the ball on both sides of the net in the third and fourth games with several players making big plays at key points, and came away with solid wins in the two games to seal the match win.

I was really pleased to see the overall team effort that the girls gave, Bratton remarked.

We really had some unselfish play out there, and that made the team concept a reality for us.

Several players drew praise from Bratton for their play.

We had some big plays from seniors Mackenzie Lawter and Rose Spainhour, Bratton noted.

Both Mackenzie and Rose led the team both on the front row and on the back row. Leigh-Anne McCormick stepped up and made some great sets and big hits to lead us on the front row.

Leigh-Anne is a great player, Bratton continued.

She is so versatile as a player that she helps the team immensely with power plays and great sets. Outside hitter Savanna Cabaniss had some big hits on the front row and held her own on the back row as well. Katie Cole stepped into several roles on the court to help with the win.

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Comets spikers down Dan River High School 3-1 in opening game – YourGV.com

Colts defeat Comets 9-0 in soccer action – Stanly News & Press

The mens soccer teams of North Stanly and West Stanly met in a non-conference matchup on Monday in Red Cross on the Colts home field.

West was playing in its second match of the season after losing 4-0 to Union Academy a week before, while North had losses last week to Mount Pleasant 5-0 and Piedmont 10-1.

Scoring three times in the first 10 minutes, West ended the match early with the mercy rule midway through the second half, winning 9-0 over the Comets.

Logan Brown led the offense for the Colts (1-1) with three goals while Aldo Cruz added a goal and two assists. Manuel Osorio and Noel Medina each added a goal and an assist, while Elvin Lonas and Leonardo Martinez each scored goals. Damian Talley, Caleb Feere and Arturo Zelaya each added an assist for West as well.

West Stanly continues non-conference road play today at Monroe while North Stanly was scheduled to open conference play Wednesday at South Davidson.

To submit story ideas, call Charles Curcio at (704) 982-2121, ext. 26, email charles@stanlynewspress.com or contact him via Twitter (@charles_curcio).

Charles Curcio is sports editor of The Stanly News & Press. Contact him at (704) 982-2121 ext. 26, charles@stanlynewspress.com or PO Box 488, Albemarle, NC 28002.

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Colts defeat Comets 9-0 in soccer action – Stanly News & Press

Comets face final test Thursday – YourGV.com

The Halifax County High School varsity and junior varsity football teams will face their final pre-season test Thursday night with a scrimmage against Colonial Heights High School.

Thursdays action at Tuck Dillard Memorial Stadium starts with a JV scrimmage at 5 p.m. followed by the varsity scrimmage at 6 p.m.

Both Comets teams were successful in their respective opening pre-season tests Friday night, with the varsity squad topping Buckingham County High School 34-14 in the annual Virginia High School League Benefit Game and the JV team outscoring Buckingham County High School four touchdowns to none in its scrimmage.

Thursdays scrimmage against Colonial Heights will be a different kind of test for the Comets varsity squad in terms of preparation, format and the level and style of the competition.

As far as preparation goes, it is quite a bit different because it cuts a day of preparation out in your normal routine, so everything is off kilter, explained Comets Head Coach Grayson Throckmorton.

Youre scrimmaging on a night you are not accustomed. You have to adjust your practice plans and your overall mindset. In the NFL, it doesnt make much difference. In college, it doesnt make much difference. With high school, it makes a lot of difference because the kids cant adjust as well as those seasoned veterans can.

Its just something weve got to do out of necessity, Throckmorton added.

The Comets are expected to see the level of the competition ramp up Thursday night when they face the Richmond-area school.

As far as team size, the number of players and the number of students in the school, Buckingham County and Colonial Heights are about the same, Throckmorton noted.

But, Colonial Heights competes in a much larger district, and they compete against the likes of Thomas Dale, Dinwiddie, Meadowbrook, Matoaca, and the list goes on. When they get into the (post-season) playoffs, they compete at the Division 3 level, but they compete mostly against Division 5 and Division 6 teams during the regular season. So, just with regard to the level of the competition they are used to competing against, Colonial Heights is going to be a better squad.

Colonial Heights, Throckmorton said, will play a different style of offense than his team saw Friday night with Buckingham County High School.

They (Colonial Heights High School) are a true spread team which we havent seen yet, explained Throckmorton.

They are going to be looking to throw the ball out in the perimeter and try to screen on us with wide receiver screens and screens in the backfield. They will be looking to use their passing game as an advantage, which is going to be good for us.

The result, Throckmorton says, is that the Comets defense will be stretched more and better play will be needed in the defensive secondary.

Were not going to be able to play as run heavy as we did Friday night, he pointed out.

Were going to have to play more 50-50 versus the run and the pass, where the other night we were playing 80 percent run and 20 percent pass. Were going to have to be more evenly balanced Thursday night.

Throckmorton and the Comets kept everything very simple in Friday nights contest against Buckingham County High School. The Comets Head Coach says he plans to expand a few things Thursday night.

Offensively, we are going to add a little more offense in, some stuff we have been working on that we didnt use and a couple of things that are brand new, Throckmorton pointed out.

Defensively, were going to add a few stunts in that we didnt use the other night. We didnt use any stunts Friday night and we are going to add some of that in on defense.

Thursday night is also going to offer Throckmorton and his coaching staff another opportunity to evaluate personnel.

We are going to continue to look at personnel, Throckmorton pointed out, and see who can play what positions and who can play what and where in the future to help us. We have a real good idea of who is where now. Where before there were some bigger adjustments the last week and a half, now its a matter of one or two (players) here and there.

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Comets face final test Thursday – YourGV.com

VOLLEY: Comets show grit in 5-set win – Kokomo Tribune

GREENTOWN When it mattered most Tuesday night, Easterns volleyball team was dialed in.

The Comets won the first two games against visiting Kokomo, then errors crept into Easterns game and Kokomos serving got sharper. The VolleyKats won games three and four to even the match and set up a decisive fifth set.

Thats when Eastern responded. The Comets took a 9-8 lead when middle hitter Hailey Holliday floored a Kokomo overpass and the Comets never trailed again, finishing off a 25-19, 26-24, 23-25, 19-25, 15-11 victory over Kokomo.

I think we finally dug deep and decided not to let up, Eastern coach Missy Mavrick said. We have a bad habit of letting up. Once we get ahead we feel comfortable, and we decided to make sure we kept pushing that [fifth] set.

Holliday and Isabel Kelly each floored 13 kills to lead the Comets and Bailey Johnson added seven kills. Each of those net players came up with important finishes in the fifth set. Johnson had three kills including a tip kill on an overpass to end the match and scored on a block. Holliday had three kills and Kelly two.

I thought our hitters played really well at the net, Mavrick said. I thought we saw the floor really well, all the way around, all of our hitters. Weve still got some kinks to work out in the back row, thats really the key to our offense is weve got to be able to pass better than what were passing. Once we fix one thing weve got to keep being aggressive and not let something else fall apart.

Kokomo had done damage in the third and fourth sets with effective service, especially from Alliyah Hochstedler and Kylee Lauderbaugh. As the fifth set played out, the service rotation worked out ideally for the Kats as Hochstedler and Lauderbaugh were Kokomos last two servers. But neither got on a run.

A strong Hochstedler serve almost aced the Comets but the home team recovered and scored on a Johnson block for a 13-10 lead. Then after a Kokomo point, Lauderbaughs serve was fielded cleanly and Kelly smoked a kill for a 14-11 lead. Johnson settled the match on the next point.

We really made sure that on receive on those two girls that we stayed focused and make sure that we pushed to get the ball back, Mavrick said.

To illustrate how much cleaner Easterns play was in the decisive set, look at the errors. In the third set, Kokomo scored points on 14 Eastern attack, serve or technique errors. The Comets gave up eight more points in the fourth game on their own errors. In the fifth set, Eastern gave away just one point via a service error and the Kats had to earn all their other points that set.

On the other side, errors took a toll.

We had a lot of momentum going into the fifth set we had all the momentum, but our inexperience in those situations showed its head with hitting errors and kind of playing safe instead of playing to win, Kokomo coach Jason Watson said.

We had five hitting errors, two serve receive errors and a block error. Thats eight of their 15 points were directly points that we give them.

When the Kats (1-6) served well, they had the advantage, but early when they struggled, serving was the problem.

Early on we struggled serving, Watson said. In the first and second set, our serving cost us in my opinion the match. At one point we missed four out of five serves and you cant beat anybody with that lack of consistency.

Gabby Cooper led the Kat attack with 16 kills, and added seven digs. Chiara Minor had 11 kills and Hochstedler had seven kills and 14 digs. Lauderbaugh finished with 41 assists, 12 digs, four kills from her setter spot and six aces. Molly Fisher added seven digs and Madison Wood six.

I liked our energy and I think we definitely have a lot to build on, Watson said.

Maci Weeks had 25 assists and Grace Kuhlman had 16 for the Comets (3-3). Casey Clark had 31 serve receives and 25 digs. Torie Bratcher served 11 points and 16 serve receives.

I thought Hailey Holliday did a great job, Mavrick said. She played very consistent through the whole night. And Isabel Kelly, shes just been our go-to. Shes been very consistent.

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VOLLEY: Comets show grit in 5-set win – Kokomo Tribune

Ecosystem – Wikipedia

This article is about natural ecosystems. For the term used in man-made systems, see Digital ecosystem.

An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. It refers to both biotic factors as well as abiotic factors.[2] An ecosystem is self supporting[3] These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows.[4] As ecosystems are defined by the network of interactions among organisms, and between organisms and their environment,[5] they can be of any size but usually encompass specific, limited spaces[6] (although some scientists say that the entire planet is an ecosystem).[7]

Energy, water, nitrogen and soil minerals are other essential abiotic components of an ecosystem. The energy that flows through ecosystems is obtained primarily from the sun. It generally enters the system through photosynthesis, a process that also captures carbon dioxide from the atmosphere. By feeding on plants and on one another, animals play an important role in the movement of matter and energy through the system. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and other microbes.[8]

Ecosystems are controlled both by external and internal factors. External factors such as climate, the parent material that forms the soil, and topography control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem.[9] Other external factors include time and potential biota. Ecosystems are dynamic entitiesinvariably, they are subject to periodic disturbances and are in the process of recovering from some past disturbance.[10] Ecosystems in similar environments that are located in different parts of the world can have very different characteristics simply because they contain different species.[9] The introduction of non-native species can cause substantial shifts in ecosystem function. Internal factors not only control ecosystem processes but are also controlled by them and are often subject to feedback loops.[9] While the resource inputs are generally controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading.[9] Other internal factors include disturbance, succession and the types of species present. Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate.[9]

Biodiversity affects ecosystem function, as do the processes of disturbance and succession. Ecosystems provide a variety of goods and services upon which people depend; the principles of ecosystem management suggest that rather than managing individual species, natural resources should be managed at the level of the ecosystem itself. Classifying ecosystems into ecologically homogeneous units is an important step towards effective ecosystem management, but there is no single, agreed-upon way to do this.

The term “ecosystem” was first used in 1935 in a publication by British ecologist Arthur Tansley.[fn 1][11] Tansley devised the concept to draw attention to the importance of transfers of materials between organisms and their environment.[12] He later refined the term, describing it as “The whole system, … including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment”.[13] Tansley regarded ecosystems not simply as natural units, but as mental isolates.[13] Tansley later[14] defined the spatial extent of ecosystems using the term ecotope.

G. Evelyn Hutchinson, a pioneering limnologist who was a contemporary of Tansley’s, combined Charles Elton’s ideas about trophic ecology with those of Russian geochemist Vladimir Vernadsky to suggest that mineral nutrient availability in a lake limited algal production which would, in turn, limit the abundance of animals that feed on algae. Raymond Lindeman took these ideas one step further to suggest that the flow of energy through a lake was the primary driver of the ecosystem. Hutchinson’s students, brothers Howard T. Odum and Eugene P. Odum, further developed a “systems approach” to the study of ecosystems, allowing them to study the flow of energy and material through ecological systems.[12]

Energy and carbon enter ecosystems through photosynthesis, are incorporated into living tissue, transferred to other organisms that feed on the living and dead plant matter, and eventually released through respiration.[15] Most mineral nutrients, on the other hand, are recycled within ecosystems.[16]

Ecosystems are controlled both by external and internal factors. External factors, also called state factors, control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem. The most important of these is climate.[9] Climate determines the biome in which the ecosystem is embedded. Rainfall patterns and temperature seasonality determine the amount of water available to the ecosystem and the supply of energy available (by influencing photosynthesis).[9]Parent material, the underlying geological material that gives rise to soils, determines the nature of the soils present, and influences the supply of mineral nutrients. Topography also controls ecosystem processes by affecting things like microclimate, soil development and the movement of water through a system. This may be the difference between the ecosystem present in wetland situated in a small depression on the landscape, and one present on an adjacent steep hillside.[9]

Other external factors that play an important role in ecosystem functioning include time and potential biota. Ecosystems are dynamic entitiesinvariably, they are subject to periodic disturbances and are in the process of recovering from some past disturbance.[10] Time plays a role in the development of soil from bare rock and the recovery of a community from disturbance.[9] Similarly, the set of organisms that can potentially be present in an area can also have a major impact on ecosystems. Ecosystems in similar environments that are located in different parts of the world can end up doing things very differently simply because they have different pools of species present.[9] The introduction of non-native species can cause substantial shifts in ecosystem function.

Unlike external factors, internal factors in ecosystems not only control ecosystem processes, but are also controlled by them. Consequently, they are often subject to feedback loops.[9] While the resource inputs are generally controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading.[9] Other factors like disturbance, succession or the types of species present are also internal factors. Human activities are important in almost all ecosystems. Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate.[9]

Primary production is the production of organic matter from inorganic carbon sources. Overwhelmingly, this occurs through photosynthesis. The energy incorporated through this process supports life on earth, while the carbon makes up much of the organic matter in living and dead biomass, soil carbon and fossil fuels. It also drives the carbon cycle, which influences global climate via the greenhouse effect.

Through the process of photosynthesis, plants capture energy from light and use it to combine carbon dioxide and water to produce carbohydrates and oxygen. The photosynthesis carried out by all the plants in an ecosystem is called the gross primary production (GPP).[17] About 4860% of the GPP is consumed in plant respiration. The remainder, that portion of GPP that is not used up by respiration, is known as the net primary production (NPP).[15] Total photosynthesis is limited by a range of environmental factors. These include the amount of light available, the amount of leaf area a plant has to capture light (shading by other plants is a major limitation of photosynthesis), rate at which carbon dioxide can be supplied to the chloroplasts to support photosynthesis, the availability of water, and the availability of suitable temperatures for carrying out photosynthesis.[17]

The carbon and energy incorporated into plant tissues (net primary production) is either consumed by animals while the plant is alive, or it remains uneaten when the plant tissue dies and becomes detritus. In terrestrial ecosystems, roughly 90% of the NPP ends up being broken down by decomposers. The remainder is either consumed by animals while still alive and enters the plant-based trophic system, or it is consumed after it has died, and enters the detritus-based trophic system. In aquatic systems, the proportion of plant biomass that gets consumed by herbivores is much higher.[19] In trophic systems photosynthetic organisms are the primary producers. The organisms that consume their tissues are called primary consumers or secondary producersherbivores. Organisms which feed on microbes (bacteria and fungi) are termed microbivores. Animals that feed on primary consumerscarnivoresare secondary consumers. Each of these constitutes a trophic level.[19] The sequence of consumptionfrom plant to herbivore, to carnivoreforms a food chain. Real systems are much more complex than thisorganisms will generally feed on more than one form of food, and may feed at more than one trophic level. Carnivores may capture some prey which are part of a plant-based trophic system and others that are part of a detritus-based trophic system (a bird that feeds both on herbivorous grasshoppers and earthworms, which consume detritus). Real systems, with all these complexities, form food webs rather than food chains.[19]

The carbon and nutrients in dead organic matter are broken down by a group of processes known as decomposition. This releases nutrients that can then be re-used for plant and microbial production, and returns carbon dioxide to the atmosphere (or water) where it can be used for photosynthesis. In the absence of decomposition, dead organic matter would accumulate in an ecosystem and nutrients and atmospheric carbon dioxide would be depleted.[20] Approximately 90% of terrestrial NPP goes directly from plant to decomposer.[19]

Decomposition processes can be separated into three categoriesleaching, fragmentation and chemical alteration of dead material. As water moves through dead organic matter, it dissolves and carries with it the water-soluble components. These are then taken up by organisms in the soil, react with mineral soil, or are transported beyond the confines of the ecosystem (and are considered “lost” to it).[20] Newly shed leaves and newly dead animals have high concentrations of water-soluble components, and include sugars, amino acids and mineral nutrients. Leaching is more important in wet environments, and much less important in dry ones.[20]

Fragmentation processes break organic material into smaller pieces, exposing new surfaces for colonization by microbes. Freshly shed leaf litter may be inaccessible due to an outer layer of cuticle or bark, and cell contents are protected by a cell wall. Newly dead animals may be covered by an exoskeleton. Fragmentation processes, which break through these protective layers, accelerate the rate of microbial decomposition.[20] Animals fragment detritus as they hunt for food, as does passage through the gut. Freeze-thaw cycles and cycles of wetting and drying also fragment dead material.[20]

The chemical alteration of dead organic matter is primarily achieved through bacterial and fungal action. Fungal hyphae produce enzymes which can break through the tough outer structures surrounding dead plant material. They also produce enzymes which break down lignin, which allows to them access to both cell contents and to the nitrogen in the lignin. Fungi can transfer carbon and nitrogen through their hyphal networks and thus, unlike bacteria, are not dependent solely on locally available resources.[20]

Decomposition rates vary among ecosystems. The rate of decomposition is governed by three sets of factorsthe physical environment (temperature, moisture and soil properties), the quantity and quality of the dead material available to decomposers, and the nature of the microbial community itself.[21] Temperature controls the rate of microbial respiration; the higher the temperature, the faster microbial decomposition occurs. It also affects soil moisture, which slows microbial growth and reduces leaching. Freeze-thaw cycles also affect decompositionfreezing temperatures kill soil microorganisms, which allows leaching to play a more important role in moving nutrients around. This can be especially important as the soil thaws in the Spring, creating a pulse of nutrients which become available.[21]

Decomposition rates are low under very wet or very dry conditions. Decomposition rates are highest in wet, moist conditions with adequate levels of oxygen. Wet soils tend to become deficient in oxygen (this is especially true in wetlands), which slows microbial growth. In dry soils, decomposition slows as well, but bacteria continue to grow (albeit at a slower rate) even after soils become too dry to support plant growth. When the rains return and soils become wet, the osmotic gradient between the bacterial cells and the soil water causes the cells to gain water quickly. Under these conditions, many bacterial cells burst, releasing a pulse of nutrients.[21] Decomposition rates also tend to be slower in acidic soils.[21] Soils which are rich in clay minerals tend to have lower decomposition rates, and thus, higher levels of organic matter.[21] The smaller particles of clay result in a larger surface area that can hold water. The higher the water content of a soil, the lower the oxygen content[22] and consequently, the lower the rate of decomposition. Clay minerals also bind particles of organic material to their surface, making them less accessibly to microbes.[21] Soil disturbance like tilling increase decomposition by increasing the amount of oxygen in the soil and by exposing new organic matter to soil microbes.[21]

The quality and quantity of the material available to decomposers is another major factor that influences the rate of decomposition. Substances like sugars and amino acids decompose readily and are considered “labile”. Cellulose and hemicellulose, which are broken down more slowly, are “moderately labile”. Compounds which are more resistant to decay, like lignin or cutin, are considered “recalcitrant”.[21] Litter with a higher proportion of labile compounds decomposes much more rapidly than does litter with a higher proportion of recalcitrant material. Consequently, dead animals decompose more rapidly than dead leaves, which themselves decompose more rapidly than fallen branches.[21] As organic material in the soil ages, its quality decreases. The more labile compounds decompose quickly, leaving an increasing proportion of recalcitrant material. Microbial cell walls also contain recalcitrant materials like chitin, and these also accumulate as the microbes die, further reducing the quality of older soil organic matter.[21]

Ecosystems continually exchange energy and carbon with the wider environment; mineral nutrients, on the other hand, are mostly cycled back and forth between plants, animals, microbes and the soil. Most nitrogen enters ecosystems through biological nitrogen fixation, is deposited through precipitation, dust, gases or is applied as fertilizer.[16] Since most terrestrial ecosystems are nitrogen-limited, nitrogen cycling is an important control on ecosystem production.[16]

Until modern times, nitrogen fixation was the major source of nitrogen for ecosystems. Nitrogen fixing bacteria either live symbiotically with plants, or live freely in the soil. The energetic cost is high for plants which support nitrogen-fixing symbiontsas much as 25% of GPP when measured in controlled conditions. Many members of the legume plant family support nitrogen-fixing symbionts. Some cyanobacteria are also capable of nitrogen fixation. These are phototrophs, which carry out photosynthesis. Like other nitrogen-fixing bacteria, they can either be free-living or have symbiotic relationships with plants.[16] Other sources of nitrogen include acid deposition produced through the combustion of fossil fuels, ammonia gas which evaporates from agricultural fields which have had fertilizers applied to them, and dust.[16] Anthropogenic nitrogen inputs account for about 80% of all nitrogen fluxes in ecosystems.[16]

When plant tissues are shed or are eaten, the nitrogen in those tissues becomes available to animals and microbes. Microbial decomposition releases nitrogen compounds from dead organic matter in the soil, where plants, fungi and bacteria compete for it. Some soil bacteria use organic nitrogen-containing compounds as a source of carbon, and release ammonium ions into the soil. This process is known as nitrogen mineralization. Others convert ammonium to nitrite and nitrate ions, a process known as nitrification. Nitric oxide and nitrous oxide are also produced during nitrification.[16] Under nitrogen-rich and oxygen-poor conditions, nitrates and nitrites are converted to nitrogen gas, a process known as denitrification.[16]

Other important nutrients include phosphorus, sulfur, calcium, potassium, magnesium and manganese.[23] Phosphorus enters ecosystems through weathering. As ecosystems age this supply diminishes, making phosphorus-limitation more common in older landscapes (especially in the tropics).[23] Calcium and sulfur are also produced by weathering, but acid deposition is an important source of sulfur in many ecosystems. Although magnesium and manganese are produced by weathering, exchanges between soil organic matter and living cells account for a significant portion of ecosystem fluxes. Potassium is primarily cycled between living cells and soil organic matter.[23]

Ecosystem processes are broad generalizations that actually take place through the actions of individual organisms. The nature of the organismsthe species, functional groups and trophic levels to which they belongdictates the sorts of actions these individuals are capable of carrying out, and the relative efficiency with which they do so. Thus, ecosystem processes are driven by the number of species in an ecosystem, the exact nature of each individual species, and the relative abundance organisms within these species.[25] Biodiversity plays an important role in ecosystem functioning.[26]

Ecological theory suggests that in order to coexist, species must have some level of limiting similaritythey must be different from one another in some fundamental way, otherwise one species would competitively exclude the other.[27] Despite this, the cumulative effect of additional species in an ecosystem is not linearadditional species may enhance nitrogen retention, for example, but beyond some level of species richness, additional species may have little additive effect.[25] The addition (or loss) of species which are ecologically similar to those already present in an ecosystem tends to only have a small effect on ecosystem function. Ecologically distinct species, on the other hand, have a much larger effect. Similarly, dominant species have a large impact on ecosystem function, while rare species tend to have a small effect. Keystone species tend to have an effect on ecosystem function that is disproportionate to their abundance in an ecosystem.[25]

Ecosystems provide a variety of goods and services upon which people depend.[28] Ecosystem goods include the “tangible, material products”[29] of ecosystem processesfood, construction material, medicinal plantsin addition to less tangible items like tourism and recreation, and genes from wild plants and animals that can be used to improve domestic species.[28] Ecosystem services, on the other hand, are generally “improvements in the condition or location of things of value”.[29] These include things like the maintenance of hydrological cycles, cleaning air and water, the maintenance of oxygen in the atmosphere, crop pollination and even things like beauty, inspiration and opportunities for research.[28] While ecosystem goods have traditionally been recognized as being the basis for things of economic value, ecosystem services tend to be taken for granted.[29] While Gretchen Daily’s original definition distinguished between ecosystem goods and ecosystem services, Robert Costanza and colleagues’ later work and that of the Millennium Ecosystem Assessment lumped all of these together as ecosystem services.[29][30]

When natural resource management is applied to whole ecosystems, rather than single species, it is termed ecosystem management.[31] A variety of definitions exist: F. Stuart Chapin and coauthors define it as “the application of ecological science to resource management to promote long-term sustainability of ecosystems and the delivery of essential ecosystem goods and services”,[32] while Norman Christensen and coauthors defined it as “management driven by explicit goals, executed by policies, protocols, and practices, and made adaptable by monitoring and research based on our best understanding of the ecological interactions and processes necessary to sustain ecosystem structure and function”[28] and Peter Brussard and colleagues defined it as “managing areas at various scales in such a way that ecosystem services and biological resources are preserved while appropriate human use and options for livelihood are sustained”.[33]

Although definitions of ecosystem management abound, there is a common set of principles which underlie these definitions.[32] A fundamental principle is the long-term sustainability of the production of goods and services by the ecosystem;[32] “intergenerational sustainability [is] a precondition for management, not an afterthought”.[28] It also requires clear goals with respect to future trajectories and behaviors of the system being managed. Other important requirements include a sound ecological understanding of the system, including connectedness, ecological dynamics and the context in which the system is embedded. Other important principles include an understanding of the role of humans as components of the ecosystems and the use of adaptive management.[28] While ecosystem management can be used as part of a plan for wilderness conservation, it can also be used in intensively managed ecosystems[28] (see, for example, agroecosystem and close to nature forestry).

Ecosystems are dynamic entitiesinvariably, they are subject to periodic disturbances and are in the process of recovering from some past disturbance.[10] When an ecosystem is subject to some sort of perturbation, it responds by moving away from its initial state. The tendency of a system to remain close to its equilibrium state, despite that disturbance, is termed its resistance. On the other hand, the speed with which it returns to its initial state after disturbance is called its resilience.[10]

From one year to another, ecosystems experience variation in their biotic and abiotic environments. A drought, an especially cold winter and a pest outbreak all constitute short-term variability in environmental conditions. Animal populations vary from year to year, building up during resource-rich periods and crashing as they overshoot their food supply. These changes play out in changes in NPP, decomposition rates, and other ecosystem processes.[10] Longer-term changes also shape ecosystem processesthe forests of eastern North America still show legacies of cultivation which ceased 200 years ago, while methane production in eastern Siberian lakes is controlled by organic matter which accumulated during the Pleistocene.[10]

Disturbance also plays an important role in ecological processes. F. Stuart Chapin and coauthors define disturbance as “a relatively discrete event in time and space that alters the structure of populations, communities and ecosystems and causes changes in resources availability or the physical environment”.[34] This can range from tree falls and insect outbreaks to hurricanes and wildfires to volcanic eruptions and can cause large changes in plant, animal and microbe populations, as well soil organic matter content.[10] Disturbance is followed by succession, a “directional change in ecosystem structure and functioning resulting from biotically driven changes in resources supply.”[34]

The frequency and severity of disturbance determines the way it impacts ecosystem function. Major disturbance like a volcanic eruption or glacial advance and retreat leave behind soils that lack plants, animals or organic matter. Ecosystems that experience disturbances that undergo primary succession. Less severe disturbance like forest fires, hurricanes or cultivation result in secondary succession.[10] More severe disturbance and more frequent disturbance result in longer recovery times. Ecosystems recover more quickly from less severe disturbance events.[10]

The early stages of primary succession are dominated by species with small propagules (seed and spores) which can be dispersed long distances. The early colonizersoften algae, cyanobacteria and lichensstabilize the substrate. Nitrogen supplies are limited in new soils, and nitrogen-fixing species tend to play an important role early in primary succession. Unlike in primary succession, the species that dominate secondary succession, are usually present from the start of the process, often in the soil seed bank. In some systems the successional pathways are fairly consistent, and thus, are easy to predict. In others, there are many possible pathwaysfor example, the introduced nitrogen-fixing legume, Myrica faya, alter successional trajectories in Hawaiian forests.[10]

The theoretical ecologist Robert Ulanowicz has used information theory tools to describe the structure of ecosystems, emphasizing mutual information (correlations) in studied systems. Drawing on this methodology and prior observations of complex ecosystems, Ulanowicz depicts approaches to determining the stress levels on ecosystems and predicting system reactions to defined types of alteration in their settings (such as increased or reduced energy flow, and eutrophication.[35]

Ecosystem ecology studies “the flow of energy and materials through organisms and the physical environment”. It seeks to understand the processes which govern the stocks of material and energy in ecosystems, and the flow of matter and energy through them. The study of ecosystems can cover 10 orders of magnitude, from the surface layers of rocks to the surface of the planet.[36]

There is no single definition of what constitutes an ecosystem.[37] German ecologist Ernst-Detlef Schulze and coauthors defined an ecosystem as an area which is “uniform regarding the biological turnover, and contains all the fluxes above and below the ground area under consideration.” They explicitly reject Gene Likens’ use of entire river catchments as “too wide a demarcation” to be a single ecosystem, given the level of heterogeneity within such an area.[38] Other authors have suggested that an ecosystem can encompass a much larger area, even the whole planet.[7] Schulze and coauthors also rejected the idea that a single rotting log could be studied as an ecosystem because the size of the flows between the log and its surroundings are too large, relative to the proportion cycles within the log.[38] Philosopher of science Mark Sagoff considers the failure to define “the kind of object it studies” to be an obstacle to the development of theory in ecosystem ecology.[37]

Ecosystems can be studied through a variety of approachestheoretical studies, studies monitoring specific ecosystems over long periods of time, those that look at differences between ecosystems to elucidate how they work and direct manipulative experimentation.[39] Studies can be carried out at a variety of scales, from microcosms and mesocosms which serve as simplified representations of ecosystems, through whole-ecosystem studies.[40] American ecologist Stephen R. Carpenter has argued that microcosm experiments can be “irrelevant and diversionary” if they are not carried out in conjunction with field studies carried out at the ecosystem scale, because microcosm experiments often fail to accurately predict ecosystem-level dynamics.[41]

The Hubbard Brook Ecosystem Study, established in the White Mountains, New Hampshire in 1963, was the first successful attempt to study an entire watershed as an ecosystem. The study used stream chemistry as a means of monitoring ecosystem properties, and developed a detailed biogeochemical model of the ecosystem.[42]Long-term research at the site led to the discovery of acid rain in North America in 1972, and was able to document the consequent depletion of soil cations (especially calcium) over the next several decades.[43]

Classifying ecosystems into ecologically homogeneous units is an important step towards effective ecosystem management.[44] A variety of systems exist, based on vegetation cover, remote sensing, and bioclimatic classification systems.[44] American geographer Robert Bailey defines a hierarchy of ecosystem units ranging from microecosystems (individual homogeneous sites, on the order of 10 square kilometres (4sqmi) in area), through mesoecosystems (landscape mosaics, on the order of 1,000 square kilometres (400sqmi)) to macroecosystems (ecoregions, on the order of 100,000 square kilometres (40,000sqmi)).[45]

Bailey outlined five different methods for identifying ecosystems: gestalt (“a whole that is not derived through considerable of its parts”), in which regions are recognized and boundaries drawn intuitively; a map overlay system where different layers like geology, landforms and soil types are overlain to identify ecosystems; multivariate clustering of site attributes; digital image processing of remotely sensed data grouping areas based on their appearance or other spectral properties; or by a “controlling factors method” where a subset of factors (like soils, climate, vegetation physiognomy or the distribution of plant or animal species) are selected from a large array of possible ones are used to delineate ecosystems.[46] In contrast with Bailey’s methodology, Puerto Rico ecologist Ariel Lugo and coauthors identified ten characteristics of an effective classification system: that it be based on georeferenced, quantitative data; that it should minimize subjectivity and explicitly identify criteria and assumptions; that it should be structured around the factors that drive ecosystem processes; that it should reflect the hierarchical nature of ecosystems; that it should be flexible enough to conform to the various scales at which ecosystem management operates; that it should be tied to reliable measures of climate so that it can “anticipat[e] global climate change; that it be applicable worldwide; that it should be validated against independent data; that it take into account the sometimes complex relationship between climate, vegetation and ecosystem functioning; and that it should be able to adapt and improve as new data become available”.[44]

As human populations and per capita consumption grow, so do the resource demands imposed on ecosystems and the impacts of the human ecological footprint. Natural resources are not invulnerable and infinitely available. The environmental impacts of anthropogenic actions, which are processes or materials derived from human activities, are becoming more apparentair and water quality are increasingly compromised, oceans are being overfished, pests and diseases are extending beyond their historical boundaries, and deforestation is exacerbating flooding downstream. It has been reported that approximately 4050% of Earth’s ice-free land surface has been heavily transformed or degraded by anthropogenic activities, 66% of marine fisheries are either overexploited or at their limit, atmospheric CO2 has increased more than 30% since the advent of industrialization, and nearly 25% of Earth’s bird species have gone extinct in the last two thousand years.[47] Society is increasingly becoming aware that ecosystem services are not only limited, but also that they are threatened by human activities. The need to better consider long-term ecosystem health and its role in enabling human habitation and economic activity is urgent. To help inform decision-makers, many ecosystem services are being assigned economic values, often based on the cost of replacement with anthropogenic alternatives. The ongoing challenge of prescribing economic value to nature, for example through biodiversity banking, is prompting transdisciplinary shifts in how we recognize and manage the environment, social responsibility, business opportunities, and our future as a species.


Ecosystem – Wikipedia

Escaped Atlantic Salmon Threaten Ecosystem Near Washington state – NewsBeat Social

UNITED NEWS INTERNATIONAL (UNI) The state of Washington is urging people to catch as many salmon as possible after thousands broke free from a fish farm and escaped into waters near the Pacific Ocean.

The problem is that these salmon are from the Atlantic Ocean, and experts fear the ecosystem could be damaged for the native Pacific salmon.

The Washington Department of Fish and Wildlife estimates between 4,000 and 5,000 Atlantic salmon escaped over the weekend into theSalish Sea.

About 305,000 fish were being held in the pen when it collapsed, allowing many to escape.

The farms owner, Cooke Aquaculture, has blamed the solar eclipse on Aug. 21 for the incident, saying it led to high tides and strong currents that damaged the pen.

The Seattle Times reports many fishermen and environmental groups dont believe the eclipse was a factor, though.

More here:

Escaped Atlantic Salmon Threaten Ecosystem Near Washington state – NewsBeat Social