Category Archives: Astronomy

A University of Wyoming professor and the endowed chair of physics will bring his experience with solar eclipses to Gillette on May 16 to prepare local residents for the Great North American Solar Eclipse in August.

Gillette and much of Wyoming is in the path of the total solar eclipse Aug. 21 that will be the first to hit the contiguous United States in 38 years, and the first one to cover so much of the U.S. since 1918.

As a result, many people from across the world are traveling to the state where the view will range from 97 percent total in Gillette to 99 percent in Casper.

Tim Slater will bring an interactive presentation to Gillette on how to safely watch a solar eclipse and use computer simulations to explain why scientists from all over the world are coming to Wyoming to observe the once-in-a-lifetime event. Hell speak about the nature of eclipses and also hand out free eclipse-viewing glasses.

Of his six presentations planned in Gillette, four are open to the public free of charge.

Hell present his 30-minute lecture to astronomy classes at Campbell County High School at 8 a.m. and 9:30 a.m. May 16 at the North Campus.

Then hell give two more programs, open to the public, at the Campbell County Public Library at 4 p.m. and 4:45 p.m.

That will be followed by two programs, also open to the public, at 7 and 7:45 p.m. in the planetarium at Sage Valley Junior High. Those interested in attending the planetarium classes still have to reserve a seat online, but the program is free. Visit supersaas.com/schedule/CCSD/Planetarium to reserve a seat, email planet@ccsd.k12.wy.us or call 307-682-4307 to leave a message.

Paul Zeleski, director of the planetarium, said Slater contacted him about offering programs in Gillette because Slater is also one of his science instructors. Slater has offered the same program in other areas of the state, including Lander and Star Valley.

Hes a smart guy, Zeleski said. Hes energetic and extremely knowledgeable.

Slater joined the UW College of Education faculty in 2008-09 as the first recipient of the Wyoming Excellence in Higher Education Endowed Chair in Science Education. He was an associate professor of astronomy at the University of Arizona at the time, where he founded the internationally recognized Conceptual Astronomy and Physics Education Research Team.

Throughout May, hes traveling across Wyoming to visit schools, public libraries and community centers to build awareness, generate excitement and help children, parents, teachers and community leaders prepare for the total eclipse of the sun.

The rest is here:

UW astronomy expert brings eclipse lessons - Gillette News Record

A South Derbyshire observatory is bidding to bag a massive cash boost from the Tesco Bags of Help initiative to help build an observatory which has been years in the planning. Rosliston Astronomy Group has secured most of the funding for the new facility, but also hopes to build a ramp which will enable people with disabilities to use the space-gazing building.

Now, organisers are urging people to vote for the project in Tesco and if their project wins the overall vote, they could be presented with 4,000 all raised from the 5p plastic bag levy.

The group's overall project is called "Outreach to the Stars", which aims to develop its work with a number of community groups around Burton and South Derbyshire.

With the observatory set to be completed in July 2017, they are hoping to raise the funds to provide an access pathway to the observatory, suitable for everyone, including those with disabilities.

Heather Lomas, treasurer for the group said: "A pathway is crucial to the success of our overall project - and will benefit a much larger group of people, young and old, interested in the sun and the stars."

"Rosliston Astronomy Group has been carrying out a range of community "outreach" activities for 17 years.We believe in encouraging lifelong learning and raising aspirations for all community groups not just our members.

"We voluntarily support Rosliston Forestry Centre, providing the astronomy aspect, at their events for the general public such as weekend science days, "Bat, Moth and Astronomy" evenings, and we hold our own events such as the solar eclipse - when more than 200 people attended.

"We work regularly with primary and secondary school class groups, with scouts, guides, and give practically-based talks to various adult groups.

"Over time at Rosliston we have noted that a number of people in the general public and community groups have found outdoor 'observing' very challenging, both during the day and even more so during the evening - using an unfamiliar object like an eyepiece, having to balance on uneven ground, in often cold temperatures, frequently in the dark - especially children, the elderly, infirm, and those with disabilities, including wheelchair users.

"To resolve these problems we have for the last two years been raising funds to build an observatory.

"Burton Mail readers have helped with this. We are grateful to South Derbyshire District Council for leasing us the land, and to the Forestry Commission for supporting us.

"The observatory will give us a safe, indoor environment with all its health and safety, enabling us to engage with an even-wider community, such as parent and child 'shared' learning, and disability groups, in addition to all the other groups - both for solar and night sky observing.

"We will be able to deliver 'practically based' learning and experiences to a much wider audience, including those who would never be able to access or afford such equipment themselves.

"However, none of this can happen unless we have a suitable access pathway, and this is why we are asking the people using Tesco Stores in and around Burton, Swadlincote, Woodville and Measham, and anyone else who are able to do so, to please help us by choosing our project ' Outreach to the Stars' for your tokens - please ask for one."

Voting is open in stores throughout May and June. Customers will cast their vote using a token given to them at the check-out in store each time they shop.

Tesco's Bags of Help project has already delivered over 28.5 million to more than 4,000 projects up and down the UK.

Every other month, when votes are collected, three groups in each of Tesco's regions will be awarded funding.

Lindsey Crompton, head of community at Tesco, said: "We are absolutely delighted to open the voting for May and June. There are some fantastic projects on the shortlists and we can't wait to see them come to life in hundreds of communities."

The new community-use observatory will be built this summer after the South Derbyshire astronomy group hit their fund-raising target of 20,000. It is hoped it will allow people young and old to discover the wonders of the universe.

They were boosted by a 10,000 grant from the South Derbyshire Community Partnership Fund.

All this means that work can begin in earnest within the grounds of Rosliston Forestry Centre. Astronomy group treasurer Heather Lomas said she was "thrilled" that they had hit their target.

Mrs Lomas said: "Gaining the last few thousand pounds was tough but Derbyshire County Council helped us out with the last bit and now it's all systems go. We're hoping that building can begin in either June or July and it will be a great facility for us to share with the community, the elderly, local schools and other community groups."

Members plan to invite schools, groups and individuals to visit the new centre to learn about and explore the universe.

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Rosliston Astronomy Group is asking shoppers to vote for them to win Tesco Bags of Help cash - Burton Mail

Astronomy (from Greek: ) is a natural science that studies celestial objects and phenomena. It applies mathematics, physics, and chemistry, in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, moons, stars, galaxies, and comets; while the phenomena include supernovae explosions, gamma ray bursts, and cosmic microwave background radiation. More generally, all astronomical phenomena that originate outside Earth's atmosphere are within the purview of astronomy. A related but distinct subject, physical cosmology, is concerned with the study of the Universe as a whole.[1]

Astronomy is the oldest of the natural sciences. The early civilizations in recorded history, such as the Babylonians, Greeks, Indians, Egyptians, Nubians, Iranians, Chinese, and Maya performed methodical observations of the night sky. Historically, astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy and the making of calendars, but professional astronomy is now often considered to be synonymous with astrophysics.[2]

During the 20th century, the field of professional astronomy split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects, which is then analyzed using basic principles of physics. Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain the observational results and observations being used to confirm theoretical results.

Astronomy is one of the few sciences where amateurs can still play an active role, especially in the discovery and observation of transient phenomena. Amateur astronomers have made and contributed to many important astronomical discoveries, such as finding new comets.

Astronomy (from the Greek from astron, "star" and - -nomia from nomos, "law" or "culture") means "law of the stars" (or "culture of the stars" depending on the translation). Astronomy should not be confused with astrology, the belief system which claims that human affairs are correlated with the positions of celestial objects.[5] Although the two fields share a common origin, they are now entirely distinct.[6]

Generally, either the term "astronomy" or "astrophysics" may be used to refer to this subject.[7][8][9] Based on strict dictionary definitions, "astronomy" refers to "the study of objects and matter outside the Earth's atmosphere and of their physical and chemical properties"[10] and "astrophysics" refers to the branch of astronomy dealing with "the behavior, physical properties, and dynamic processes of celestial objects and phenomena".[11] In some cases, as in the introduction of the introductory textbook The Physical Universe by Frank Shu, "astronomy" may be used to describe the qualitative study of the subject, whereas "astrophysics" is used to describe the physics-oriented version of the subject.[12] However, since most modern astronomical research deals with subjects related to physics, modern astronomy could actually be called astrophysics.[7] Few fields, such as astrometry, are purely astronomy rather than also astrophysics. Various departments in which scientists carry out research on this subject may use "astronomy" and "astrophysics," partly depending on whether the department is historically affiliated with a physics department,[8] and many professional astronomers have physics rather than astronomy degrees.[9] Some titles of the leading scientific journals in this field includeThe Astronomical Journal, The Astrophysical Journal and Astronomy and Astrophysics.

In early times, astronomy only comprised the observation and predictions of the motions of objects visible to the naked eye. In some locations, early cultures assembled massive artifacts that possibly had some astronomical purpose. In addition to their ceremonial uses, these observatories could be employed to determine the seasons, an important factor in knowing when to plant crops, as well as in understanding the length of the year.[13]

Before tools such as the telescope were invented, early study of the stars was conducted using the naked eye. As civilizations developed, most notably in Mesopotamia, Greece, Persia, India, China, Egypt, and Central America, astronomical observatories were assembled, and ideas on the nature of the Universe began to be explored. Most of early astronomy actually consisted of mapping the positions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas about the motions of the planets were formed, and the nature of the Sun, Moon and the Earth in the Universe were explored philosophically. The Earth was believed to be the center of the Universe with the Sun, the Moon and the stars rotating around it. This is known as the geocentric model of the Universe, or the Ptolemaic system, named after Ptolemy.[14]

A particularly important early development was the beginning of mathematical and scientific astronomy, which began among the Babylonians, who laid the foundations for the later astronomical traditions that developed in many other civilizations.[15] The Babylonians discovered that lunar eclipses recurred in a repeating cycle known as a saros.[16]

Following the Babylonians, significant advances in astronomy were made in ancient Greece and the Hellenistic world. Greek astronomy is characterized from the start by seeking a rational, physical explanation for celestial phenomena.[17] In the 3rd century BC, Aristarchus of Samos estimated the size and distance of the Moon and Sun, and was the first to propose a heliocentric model of the solar system.[18] In the 2nd century BC, Hipparchus discovered precession, calculated the size and distance of the Moon and invented the earliest known astronomical devices such as the astrolabe.[19] Hipparchus also created a comprehensive catalog of 1020 stars, and most of the constellations of the northern hemisphere derive from Greek astronomy.[20] The Antikythera mechanism (c. 15080 BC) was an early analog computer designed to calculate the location of the Sun, Moon, and planets for a given date. Technological artifacts of similar complexity did not reappear until the 14th century, when mechanical astronomical clocks appeared in Europe.[21]

During the Middle Ages, astronomy was mostly stagnant in medieval Europe, at least until the 13th century. However, astronomy flourished in the Islamic world and other parts of the world. This led to the emergence of the first astronomical observatories in the Muslim world by the early 9th century.[22][23][24] In 964, the Andromeda Galaxy, the largest galaxy in the Local Group, was discovered by the Persian astronomer Azophi and first described in his Book of Fixed Stars.[25] The SN 1006 supernova, the brightest apparent magnitude stellar event in recorded history, was observed by the Egyptian Arabic astronomer Ali ibn Ridwan and the Chinese astronomers in 1006. Some of the prominent Islamic (mostly Persian and Arab) astronomers who made significant contributions to the science include Al-Battani, Thebit, Azophi, Albumasar, Biruni, Arzachel, Al-Birjandi, and the astronomers of the Maragheh and Samarkand observatories. Astronomers during that time introduced many Arabic names now used for individual stars.[26][27] It is also believed that the ruins at Great Zimbabwe and Timbuktu[28] may have housed an astronomical observatory.[29] Europeans had previously believed that there had been no astronomical observation in pre-colonial Middle Ages sub-Saharan Africa but modern discoveries show otherwise.[30][31][32][33]

The Roman Catholic Church gave more financial and social support to the study of astronomy for over six centuries, from the recovery of ancient learning during the late Middle Ages into the Enlightenment, than any other, and, probably, all other, institutions. Among the Church's motives was finding the date for Easter.[34]

During the Renaissance, Nicolaus Copernicus proposed a heliocentric model of the solar system. His work was defended, expanded upon, and corrected by Galileo Galilei and Johannes Kepler. Galileo used telescopes to enhance his observations.[35]

Kepler was the first to devise a system that described correctly the details of the motion of the planets with the Sun at the center. However, Kepler did not succeed in formulating a theory behind the laws he wrote down.[36] It was left to Newton's invention of celestial dynamics and his law of gravitation to finally explain the motions of the planets. Newton also developed the reflecting telescope.[35]

The English astronomer John Flamsteed catalogued over 3000 stars.[37] Further discoveries paralleled the improvements in the size and quality of the telescope. More extensive star catalogues were produced by Lacaille. The astronomer William Herschel made a detailed catalog of nebulosity and clusters, and in 1781 discovered the planet Uranus, the first new planet found.[38] The distance to a star was first announced in 1838 when the parallax of 61 Cygni was measured by Friedrich Bessel.[39]

During the 1819th centuries, the study of the three body problem by Euler, Clairaut, and D'Alembert led to more accurate predictions about the motions of the Moon and planets. This work was further refined by Lagrange and Laplace, allowing the masses of the planets and moons to be estimated from their perturbations.[40]

Significant advances in astronomy came about with the introduction of new technology, including the spectroscope and photography. Fraunhofer discovered about 600 bands in the spectrum of the Sun in 181415, which, in 1859, Kirchhoff ascribed to the presence of different elements. Stars were proven to be similar to the Earth's own Sun, but with a wide range of temperatures, masses, and sizes.[26]

The existence of the Earth's galaxy, the Milky Way, as a separate group of stars, was only proved in the 20th century, along with the existence of "external" galaxies. The observed recession of those galaxies led to the discovery of the expansion of the Universe.[41] Theoretical astronomy led to speculations on the existence of objects such as black holes and neutron stars, which have been used to explain such observed phenomena as quasars, pulsars, blazars, and radio galaxies. Physical cosmology made huge advances during the 20th century, with the model of the Big Bang, which is heavily supported by evidence provided by cosmic microwave background radiation, Hubble's law, and the cosmological abundances of elements. Space telescopes have enabled measurements in parts of the electromagnetic spectrum normally blocked or blurred by the atmosphere. In February 2016, it was revealed that the LIGO project had detected evidence of gravitational waves in the previous September.

Our main source of information about celestial bodies and other objects is visible light more generally electromagnetic radiation.[42] Observational astronomy may be divided according to the observed region of the electromagnetic spectrum. Some parts of the spectrum can be observed from the Earth's surface, while other parts are only observable from either high altitudes or outside the Earth's atmosphere. Specific information on these subfields is given below.

Radio astronomy uses radiation outside the visible range with wavelengths greater than approximately one millimeter.[43] Radio astronomy is different from most other forms of observational astronomy in that the observed radio waves can be treated as waves rather than as discrete photons. Hence, it is relatively easier to measure both the amplitude and phase of radio waves, whereas this is not as easily done at shorter wavelengths.[43]

Although some radio waves are emitted directly by astronomical objects, a product of thermal emission, most of the radio emission that is observed is the result of synchrotron radiation, which is produced when electrons orbit magnetic fields.[43] Additionally, a number of spectral lines produced by interstellar gas, notably the hydrogen spectral line at 21cm, are observable at radio wavelengths.[12][43]

A wide variety of objects are observable at radio wavelengths, including supernovae, interstellar gas, pulsars, and active galactic nuclei.[12][43]

Infrared astronomy is founded on the detection and analysis of infrared radiation, wavelengths longer than red light and outside the range of our vision. The infrared spectrum is useful for studying objects that are too cold to radiate visible light, such as planets, circumstellar disks or nebulae whose light is blocked by dust. The longer wavelengths of infrared can penetrate clouds of dust that block visible light, allowing the observation of young stars embedded in molecular clouds and the cores of galaxies. Observations from the Wide-field Infrared Survey Explorer (WISE) have been particularly effective at unveiling numerous Galactic protostars and their host star clusters.[45][46] With the exception of infrared wavelengths close to visible light, such radiation is heavily absorbed by the atmosphere, or masked, as the atmosphere itself produces significant infrared emission. Consequently, infrared observatories have to be located in high, dry places on Earth or in space.[47] Some molecules radiate strongly in the infrared. This allows the study of the chemistry of space; more specifically it can detect water in comets.[48]

Historically, optical astronomy, also called visible light astronomy, is the oldest form of astronomy.[49] Images of observations were originally drawn by hand. In the late 19th century and most of the 20th century, images were made using photographic equipment. Modern images are made using digital detectors, particularly using charge-coupled devices (CCDs) and recorded on modern medium. Although visible light itself extends from approximately 4000 to 7000 (400 nm to 700nm),[49] that same equipment can be used to observe some near-ultraviolet and near-infrared radiation.

Ultraviolet astronomy employs ultraviolet wavelengths between approximately 100 and 3200 (10 to 320nm).[43] Light at those wavelengths are absorbed by the Earth's atmosphere, requiring observations at these wavelengths to be performed from the upper atmosphere or from space. Ultraviolet astronomy is best suited to the study of thermal radiation and spectral emission lines from hot blue stars (OB stars) that are very bright in this wave band. This includes the blue stars in other galaxies, which have been the targets of several ultraviolet surveys. Other objects commonly observed in ultraviolet light include planetary nebulae, supernova remnants, and active galactic nuclei.[43] However, as ultraviolet light is easily absorbed by interstellar dust, an adjustment of ultraviolet measurements is necessary.[43]

X-ray astronomy uses X-ray wavelengths. Typically, X-ray radiation is produced by synchrotron emission (the result of electrons orbiting magnetic field lines), thermal emission from thin gases above 107 (10million) kelvins, and thermal emission from thick gases above 107 Kelvin.[43] Since X-rays are absorbed by the Earth's atmosphere, all X-ray observations must be performed from high-altitude balloons, rockets, or X-ray astronomy satellites. Notable X-ray sources include X-ray binaries, pulsars, supernova remnants, elliptical galaxies, clusters of galaxies, and active galactic nuclei.[43]

Gamma ray astronomy observes astronomical objects at the shortest wavelengths of the electromagnetic spectrum. Gamma rays may be observed directly by satellites such as the Compton Gamma Ray Observatory or by specialized telescopes called atmospheric Cherenkov telescopes.[43] The Cherenkov telescopes do not detect the gamma rays directly but instead detect the flashes of visible light produced when gamma rays are absorbed by the Earth's atmosphere.[50]

Most gamma-ray emitting sources are actually gamma-ray bursts, objects which only produce gamma radiation for a few milliseconds to thousands of seconds before fading away. Only 10% of gamma-ray sources are non-transient sources. These steady gamma-ray emitters include pulsars, neutron stars, and black hole candidates such as active galactic nuclei.[43]

In addition to electromagnetic radiation, a few other events originating from great distances may be observed from the Earth.

In neutrino astronomy, astronomers use heavily shielded underground facilities such as SAGE, GALLEX, and Kamioka II/III for the detection of neutrinos. The vast majority of the neutrinos streaming through the Earth originate from the Sun, but 24 neutrinos were also detected from supernova 1987A.[43]Cosmic rays, which consist of very high energy particles (atomic nuclei) that can decay or be absorbed when they enter the Earth's atmosphere, result in a cascade of secondary particles which can be detected by current observatories.[51] Some future neutrino detectors may also be sensitive to the particles produced when cosmic rays hit the Earth's atmosphere.[43]

Gravitational-wave astronomy is an emerging field of astronomy that employs gravitational-wave detectors to collect observational data about distant massive objects. A few observatories have been constructed, such as the Laser Interferometer Gravitational Observatory LIGO. LIGO made its first detection on 14 September 2015, observing gravitational waves from a binary black hole.[52] A second gravitational wave was detected on 26 December 2015 and additional observations should continue but gravitational waves require extremely sensitive instruments.[53][54]

The combination of observations made using electromagnetic radiation, neutrinos or gravitational waves and other complementary information, is known as multi-messenger astronomy.[55][56]

One of the oldest fields in astronomy, and in all of science, is the measurement of the positions of celestial objects. Historically, accurate knowledge of the positions of the Sun, Moon, planets and stars has been essential in celestial navigation (the use of celestial objects to guide navigation) and in the making of calendars.

Careful measurement of the positions of the planets has led to a solid understanding of gravitational perturbations, and an ability to determine past and future positions of the planets with great accuracy, a field known as celestial mechanics. More recently the tracking of near-Earth objects will allow for predictions of close encounters or potential collisions of the Earth with those objects.[57]

The measurement of stellar parallax of nearby stars provides a fundamental baseline in the cosmic distance ladder that is used to measure the scale of the Universe. Parallax measurements of nearby stars provide an absolute baseline for the properties of more distant stars, as their properties can be compared. Measurements of the radial velocity and proper motion motion of stars allows astronomers to plot the movement of these systems through the Milky Way galaxy. Astrometric results are the basis used to calculate the distribution of speculated dark matter in the galaxy.[58]

During the 1990s, the measurement of the stellar wobble of nearby stars was used to detect large extrasolar planets orbiting those stars.[59]

Theoretical astronomers use several tools including analytical models and computational numerical simulations; each has its particular advantages. Analytical models of a process are generally better for giving broader insight into the heart of what is going on. Numerical models reveal the existence of phenomena and effects otherwise unobserved.[60][61]

Theorists in astronomy endeavor to create theoretical models and from the results predict observational consequences of those models. The observation of a phenomenon predicted by a model allows astronomers to select between several alternate or conflicting models as the one best able to describe the phenomena.

Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency between the data and model's results, the general tendency is to try to make minimal modifications to the model so that it produces results that fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.

Phenomena modeled by theoretical astronomers include: stellar dynamics and evolution; galaxy formation; large-scale distribution of matter in the Universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics. Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole (astro)physics and the study of gravitational waves.

Some widely accepted and studied theories and models in astronomy, now included in the Lambda-CDM model are the Big Bang, Cosmic inflation, dark matter, and fundamental theories of physics.

A few examples of this process:

Dark matter and dark energy are the current leading topics in astronomy,[62] as their discovery and controversy originated during the study of the galaxies.

At a distance of about eight light-minutes, the most frequently studied star is the Sun, a typical main-sequence dwarf star of stellar class G2 V, and about 4.6 billion years (Gyr) old. The Sun is not considered a variable star, but it does undergo periodic changes in activity known as the sunspot cycle. This is an 11-year oscillation in sunspot number. Sunspots are regions of lower-than- average temperatures that are associated with intense magnetic activity.[63]

The Sun has steadily increased in luminosity by 40% since it first became a main-sequence star. The Sun has also undergone periodic changes in luminosity that can have a significant impact on the Earth.[64] The Maunder minimum, for example, is believed to have caused the Little Ice Age phenomenon during the Middle Ages.[65]

The visible outer surface of the Sun is called the photosphere. Above this layer is a thin region known as the chromosphere. This is surrounded by a transition region of rapidly increasing temperatures, and finally by the super-heated corona.

At the center of the Sun is the core region, a volume of sufficient temperature and pressure for nuclear fusion to occur. Above the core is the radiation zone, where the plasma conveys the energy flux by means of radiation. Above that is the convection zone where the gas material transports energy primarily through physical displacement of the gas known as convection. It is believed that the movement of mass within the convection zone creates the magnetic activity that generates sunspots.[63]

A solar wind of plasma particles constantly streams outward from the Sun until, at the outermost limit of the Solar System, it reaches the heliopause. As the solar wind passes the Earth, it interacts with the Earth's magnetic field (magnetosphere) and deflects the solar wind, but traps some creating the Van Allen radiation belts that envelop the Earth . The aurora are created when solar wind particles are guided by the magnetic flux lines into the Earth's polar regions where the lines the descend into the atmosphere.[66]

Planetary science is the study of the assemblage of planets, moons, dwarf planets, comets, asteroids, and other bodies orbiting the Sun, as well as extrasolar planets. The Solar System has been relatively well-studied, initially through telescopes and then later by spacecraft. This has provided a good overall understanding of the formation and evolution of this planetary system, although many new discoveries are still being made.[67]

The Solar System is subdivided into the inner planets, the asteroid belt, and the outer planets. The inner terrestrial planets consist of Mercury, Venus, Earth, and Mars. The outer gas giant planets are Jupiter, Saturn, Uranus, and Neptune.[68] Beyond Neptune lies the Kuiper Belt, and finally the Oort Cloud, which may extend as far as a light-year.

The planets were formed 4.6 billion years ago in the protoplanetary disk that surrounded the early Sun. Through a process that included gravitational attraction, collision, and accretion, the disk formed clumps of matter that, with time, became protoplanets. The radiation pressure of the solar wind then expelled most of the unaccreted matter, and only those planets with sufficient mass retained their gaseous atmosphere. The planets continued to sweep up, or eject, the remaining matter during a period of intense bombardment, evidenced by the many impact craters on the Moon. During this period, some of the protoplanets may have collided and one such collision may have formed the Moon.[69]

Once a planet reaches sufficient mass, the materials of different densities segregate within, during planetary differentiation. This process can form a stony or metallic core, surrounded by a mantle and an outer crust. The core may include solid and liquid regions, and some planetary cores generate their own magnetic field, which can protect their atmospheres from solar wind stripping.[70]

A planet or moon's interior heat is produced from the collisions that created the body, by the decay of radioactive materials (e.g. uranium, thorium, and 26Al), or tidal heating caused by interactions with other bodies. Some planets and moons accumulate enough heat to drive geologic processes such as volcanism and tectonics. Those that accumulate or retain an atmosphere can also undergo surface erosion from wind or water. Smaller bodies, without tidal heating, cool more quickly; and their geological activity ceases with the exception of impact cratering.[71]

The study of stars and stellar evolution is fundamental to our understanding of the Universe. The astrophysics of stars has been determined through observation and theoretical understanding; and from computer simulations of the interior.[72]Star formation occurs in dense regions of dust and gas, known as giant molecular clouds. When destabilized, cloud fragments can collapse under the influence of gravity, to form a protostar. A sufficiently dense, and hot, core region will trigger nuclear fusion, thus creating a main-sequence star.[73]

Almost all elements heavier than hydrogen and helium were created inside the cores of stars.[72]

The characteristics of the resulting star depend primarily upon its starting mass. The more massive the star, the greater its luminosity, and the more rapidly it fuses its hydrogen fuel into helium in its core. Over time, this hydrogen fuel is completely converted into helium, and the star begins to evolve. The fusion of helium requires a higher core temperature. A star with a high enough core temperature will push its outer layers outward while increasing its core density. The resulting red giant formed by the expanding outer layers enjoys a brief life span, before the helium fuel in the core is in turn consumed. Very massive stars can also undergo a series of evolutionary phases, as they fuse increasingly heavier elements.[74]

The final fate of the star depends on its mass, with stars of mass greater than about eight times the Sun becoming core collapse supernovae;[75] while smaller stars blow off their outer layers and leave behind the inert core in the form of a white dwarf. The ejection of the outer layers forms a planetary nebulae.[76] The remnant of a supernova is a dense neutron star, or, if the stellar mass was at least three times that of the Sun, a black hole.[77] Closely orbiting binary stars can follow more complex evolutionary paths, such as mass transfer onto a white dwarf companion that can potentially cause a supernova.[78] Planetary nebulae and supernovae distribute the "metals" produced in the star by fusion to the interstellar medium; without them, all new stars (and their planetary systems) would be formed from hydrogen and helium alone.[79]

Our solar system orbits within the Milky Way, a barred spiral galaxy that is a prominent member of the Local Group of galaxies. It is a rotating mass of gas, dust, stars and other objects, held together by mutual gravitational attraction. As the Earth is located within the dusty outer arms, there are large portions of the Milky Way that are obscured from view.

In the center of the Milky Way is the core, a bar-shaped bulge with what is believed to be a supermassive black hole at its center. This is surrounded by four primary arms that spiral from the core. This is a region of active star formation that contains many younger, population I stars. The disk is surrounded by a spheroid halo of older, population II stars, as well as relatively dense concentrations of stars known as globular clusters.[80]

Between the stars lies the interstellar medium, a region of sparse matter. In the densest regions, molecular clouds of molecular hydrogen and other elements create star-forming regions. These begin as a compact pre-stellar core or dark nebulae, which concentrate and collapse (in volumes determined by the Jeans length) to form compact protostars.[73]

As the more massive stars appear, they transform the cloud into an H II region (ionized atomic hydrogen) of glowing gas and plasma. The stellar wind and supernova explosions from these stars eventually cause the cloud to disperse, often leaving behind one or more young open clusters of stars. These clusters gradually disperse, and the stars join the population of the Milky Way.[81]

Kinematic studies of matter in the Milky Way and other galaxies have demonstrated that there is more mass than can be accounted for by visible matter. A dark matter halo appears to dominate the mass, although the nature of this dark matter remains undetermined.[82]

The study of objects outside our galaxy is a branch of astronomy concerned with the formation and evolution of Galaxies, their morphology (description) and classification, the observation of active galaxies, and at a larger scale, the groups and clusters of galaxies. Finally, the latter is important for the understanding of the large-scale structure of the cosmos.

Most galaxies are organized into distinct shapes that allow for classification schemes. They are commonly divided into spiral, elliptical and Irregular galaxies.[83]

As the name suggests, an elliptical galaxy has the cross-sectional shape of an ellipse. The stars move along random orbits with no preferred direction. These galaxies contain little or no interstellar dust, few star-forming regions, and generally older stars. Elliptical galaxies are more commonly found at the core of galactic clusters, and may have been formed through mergers of large galaxies.

A spiral galaxy is organized into a flat, rotating disk, usually with a prominent bulge or bar at the center, and trailing bright arms that spiral outward. The arms are dusty regions of star formation within which massive young stars produce a blue tint. Spiral galaxies are typically surrounded by a halo of older stars. Both the Milky Way and one of our nearest galaxy neighbors, the Andromeda Galaxy, are spiral galaxies.

Irregular galaxies are chaotic in appearance, and are neither spiral nor elliptical. About a quarter of all galaxies are irregular, and the peculiar shapes of such galaxies may be the result of gravitational interaction.

An active galaxy is a formation that emits a significant amount of its energy from a source other than its stars, dust and gas. It is powered by a compact region at the core, thought to be a super-massive black hole that is emitting radiation from in-falling material.

A radio galaxy is an active galaxy that is very luminous in the radio portion of the spectrum, and is emitting immense plumes or lobes of gas. Active galaxies that emit shorter frequency, high-energy radiation include Seyfert galaxies, Quasars, and Blazars. Quasars are believed to be the most consistently luminous objects in the known universe.[84]

The large-scale structure of the cosmos is represented by groups and clusters of galaxies. This structure is organized into a hierarchy of groupings, with the largest being the superclusters. The collective matter is formed into filaments and walls, leaving large voids between.[85]

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Cosmology (from the Greek (kosmos) "world, universe" and (logos) "word, study" or literally "logic") could be considered the study of the Universe as a whole.

Observations of the large-scale structure of the Universe, a branch known as physical cosmology, have provided a deep understanding of the formation and evolution of the cosmos. Fundamental to modern cosmology is the well-accepted theory of the big bang, wherein our Universe began at a single point in time, and thereafter expanded over the course of 13.8 billion years[86] to its present condition.[87] The concept of the big bang can be traced back to the discovery of the microwave background radiation in 1965.[87]

In the course of this expansion, the Universe underwent several evolutionary stages. In the very early moments, it is theorized that the Universe experienced a very rapid cosmic inflation, which homogenized the starting conditions. Thereafter, nucleosynthesis produced the elemental abundance of the early Universe.[87] (See also nucleocosmochronology.)

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Astronomy - Wikipedia

Photo by Eric Goodwin / Assistant News Editor

Astronomy and Physics Professor Eric Klumpe provided a lecture on eclipses Friday night in the Wiser-Patten Science Hall as a part of MTSUs First Friday Star Party series.

The lecture, titled Funky Fiziks in Film, addressedmovies involving eclipses and the upcoming solar eclipse that will occur on Aug. 21.

Klumpe explained how a solar eclipse occurs when the Earths moon passes in between the Earth and the Sun, casting a shadow across the face of the Earth. While these eclipses take place about twice a year, this one is special.

The place where (the moons shadow) touches the Earth is the continental United States. And the path, which is very narrow, includes Tennessee, he said.

Murfreesboro lies along the path of totality, meaning the sun will be obscured almost completely in Murfreesboro for a few moments.

Klumpe said the moons shadow is just a little pinpoint of darkness, and we happen to be on that path.

The eclipse, whose path of totality hasnt crossedthe Middle Tennessee regionsince 1478, will occur at roughly noon. The moon will block part of the sun for about three hours, culminating in totality for about one and a half minutes at around 1:30 p.m.

The next eclipse like this wont occur until the year 2566.

Klumpe also talked about movies in pop culture that feature solar eclipses and their hard-to-catch inaccuracies.

For example, in the 1985 film, Ladyhawke, the solar eclipse moves from left to right across the sun. Klumpe explained how the movies setting in the Northern Hemisphere means the moon should pass from the right side of the sun to the left when observed from the Earth.

Klumpe also talked about the eclipse scenes in the 1949 movie, A Connecticut Yankee in King Arthurs Court, and the 2002 movie, The Wild Thornberrys Movie.

Monty Hershberger, 43, came to the star party for the first time on Friday.

It was all very enjoyable, Hershberger said. I enjoyed (Klumpes) humor and the clips that he used to talk about it. So, it was fun.

Hershberger said he and his family will prepare for the August eclipse by hanging outside and enjoying a picnic.

Klumpe, who used to host all of the star parties when the series began, recommended attendees to take an astronomy course at MTSU regardless of their major.

Youre going to learn a lot of things youve never thought about before, he said.

To contact News Editor Andrew Wigdor, email newseditor@mtsusidelines.com.

For more news, follow us at http://www.mtsusidelines.com, on Facebook at MTSU Sidelines and on Twitter at @Sidelines_News.

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Final MTSU Star Party of the semester hosted by physics, astronomy departments - Sidelines Online (subscription)

Photo: Courtesy Of UC Berkeley, Handout Photo

Harold Weavers discov ery led to a new science.

Harold Weavers discov ery led to a new science.

Harold F. Weaver, pioneer of radio astronomy at UC Berkeley, dies

Harold F. Weaver, a pioneering UC Berkeley astronomer whose discovery of radio emissions from molecules in outer space marked the new science of radio astronomy, has died at his East Bay home in Kensington. He was 99.

Nearly 60 years ago, Professor Weaver created the universitys first radio astronomy observatory at Hat Creek, a remote valley in Plumas County 290 miles from the Berkeley campus. The surrounding mountains shielded the observatory from interference by aircraft signals and the radio noises of civilization.

Its big receiver, a dish-shaped antenna, 85 feet in diameter, would lead to major discoveries and become the mainstay of the UC Radio Astronomy Laboratory, which Professor Weaver had founded on the Berkeley campus in 1958. He would direct it for the next 15 years.

At their Hat Creek observatory, Professor Weaver and his colleagues discovered the existence of astrophysical masers the equivalent in outer space of the lasers that had been created eight years earlier by UC Berkeleys Nobel laureate physicist Charles Townes. The masers were the first evidence that objects in the gas clouds of the galaxy were emitting coherent radiation.

Professor Weaver would later discover the first interstellar molecules known as hydroxyl radicals at a time when their mysterious radio emissions were often attributed to an unknown form of space matter named mysterium. Since his discovery, many other interstellar molecules have been detected in the atmosphere of comets.

His curiosity about the universe was wide: Even as a young astronomer on the Berkeley faculty in 1953 he was using galactic star clusters and Cepheid variable stars to calculate the outer limits of the Milky Way galaxy and to estimate that the universe was at least 3.6 billion years old close to todays estimates of 4 billion years.

Ten years later, he and the late Martin Schwartzchild of Princeton University launched a giant balloon from Palestine, Texas, in a project called Stratoscope. A 2-ton telescope carried by the balloon to an altitude of 15 miles peered at Mars and discovered the worlds first evidence of water vapor in the Martian atmosphere before it crashed in a mud-filled Louisiana cow pasture.

Harold Francis Weaver was born in San Jose in 1917, and by high school he was already building his own telescopes.

Still, he debated whether he would study classics or astronomy in college. The poet Robinson Jeffers had a telescope in his Carmel home, and encouraged the young man in his telescope-building interests.

As a UC Berkeley undergraduate in the astronomy department, he met his future wife, Cecile Trumpler, the daughter of astronomer Robert Julius Trumpler, and the two were married in 1939. It was Professor Trumpler who supervised his doctoral dissertation, and the two later collaborated on a book called Statistical Astronomy, which was published in 1953 and is still in use.

During World War II, he was conscripted to work on optics research for the National Defense Research Committee and later worked on isotope separation at what was then known as the Berkeley Radiation Lab.

After the war, he served as a staff scientist at Lick Observatory and joined the astronomy faculty at UC Berkeley in 1951. He retired as a professor in 1988 after publishing more than 70 professional papers and helping to guide development of the expanding Berkeley campus as a member and chairman of the Campus Facilities Committee in the 1950s and 1960s. He helped design the astronomy departments Campbell Hall, which was recently demolished and rebuilt on the same site.

Harold was truly a giant in our department of astronomy, UC astronomy Professor Alex Filippenko said after Professor Weavers April 26 death. I will always remember his warm smile, his generosity, and how he kept going with his research and other activities well into old age.

Professor Weaver had long served as treasurer both of the American Astronomical Society and Astronomical Society of the Pacific, and was a member of the group that founded the Chabot Space and Science Center in Oakland, where he served on the board of directors for many years.

He was also interested in contemporary writing, and for many years served as treasurer and a director of the Squaw Valley Community of Writers, a summer creative writing project located near Lake Tahoe.

The Weavers have donated their longtime Kensington home to UC to be used after their deaths to fund the Trumpler-Weaver Endowed Professorship in Astronomy at UC Berkeley.

Professor Weaver is survived by his wife and three children, Margot of Tucson, Paul of Kensington and Kirk of Houston.

Memorial gifts may be made to the Cal Alumni Leadership Award in care of the California Alumni Association, 1 Alumni House, Berkeley, CA 94720.

A memorial service is being arranged.

David Perlman is The San Francisco Chronicles science editor. Email: dperlman@sfchronicle.com

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Harold F. Weaver, pioneer of radio astronomy at UC Berkeley, dies - SFGate

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 May 6

Explanation: Some 4 billion light-years away, massive galaxy cluster Abell 370 only appears to be dominated by two giant elliptical galaxies and infested with faint arcs in this sharp Hubble Space Telescope snapshot. The fainter, scattered bluish arcs along with the dramatic dragon arc below and left of center are images of galaxies that lie far beyond Abell 370. About twice as distant, their otherwise undetected light is magnified and distorted by the cluster's enormous gravitational mass, dominated by unseen dark matter. Providing a tantalizing glimpse of galaxies in the early universe, the effect is known as gravitational lensing. A consequence of warped spacetime it was first predicted by Einstein a century ago. Far beyond the spiky foreground Milky Way star at lower right, Abell 370 is seen toward the constellation Cetus, the Sea Monster. It is the last of six galaxy clusters imaged in the recently concluded Frontier Fields project.

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) NASA Official: Phillip Newman Specific rights apply. NASA Web Privacy Policy and Important Notices A service of: ASD at NASA / GSFC & Michigan Tech. U.

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Astronomy Picture of the Day

Harold F. Weaver, a pioneering UC Berkeley astronomer whose discovery of radio emissions from molecules in outer space marked the new science of radio astronomy, has died at his East Bay home in Kensington. He was 99.

Nearly 60 years ago, Professor Weaver created the universitys first radio astronomy observatory at Hat Creek, a remote valley in Plumas County 290 miles from the Berkeley campus. The surrounding mountains shielded the observatory from interference by aircraft signals and the radio noises of civilization.

Its big receiver, a dish-shaped antenna, 85 feet in diameter, would lead to major discoveries and become the mainstay of the UC Radio Astronomy Laboratory, which Professor Weaver had founded on the Berkeley campus in 1958. He would direct it for the next 15 years.

At their Hat Creek observatory, Professor Weaver and his colleagues discovered the existence of astrophysical masers the equivalent in outer space of the lasers that had been created eight years earlier by UC Berkeleys Nobel laureate physicist Charles Townes. The masers were the first evidence that objects in the gas clouds of the galaxy were emitting coherent radiation.

Professor Weaver would later discover the first interstellar molecules known as hydroxyl radicals at a time when their mysterious radio emissions were often attributed to an unknown form of space matter named mysterium. Since his discovery, many other interstellar molecules have been detected in the atmosphere of comets.

His curiosity about the universe was wide: Even as a young astronomer on the Berkeley faculty in 1953 he was using galactic star clusters and Cepheid variable stars to calculate the outer limits of the Milky Way galaxy and to estimate that the universe was at least 3.6 billion years old close to todays estimates of 4 billion years.

Ten years later, he and the late Martin Schwartzchild of Princeton University launched a giant balloon from Palestine, Texas, in a project called Stratoscope. A 2-ton telescope carried by the balloon to an altitude of 15 miles peered at Mars and discovered the worlds first evidence of water vapor in the Martian atmosphere before it crashed in a mud-filled Louisiana cow pasture.

Harold Francis Weaver was born in San Jose in 1917, and by high school he was already building his own telescopes.

Still, he debated whether he would study classics or astronomy in college. The poet Robinson Jeffers had a telescope in his Carmel home, and encouraged the young man in his telescope-building interests.

As a UC Berkeley undergraduate in the astronomy department, he met his future wife, Cecile Trumpler, the daughter of astronomer Robert Julius Trumpler, and the two were married in 1939. It was Professor Trumpler who supervised his doctoral dissertation, and the two later collaborated on a book called Statistical Astronomy, which was published in 1953 and is still in use.

During World War II, he was conscripted to work on optics research for the National Defense Research Committee and later worked on isotope separation at what was then known as the Berkeley Radiation Lab.

After the war, he served as a staff scientist at Lick Observatory and joined the astronomy faculty at UC Berkeley in 1951. He retired as a professor in 1988 after publishing more than 70 professional papers and helping to guide development of the expanding Berkeley campus as a member and chairman of the Campus Facilities Committee in the 1950s and 1960s. He helped design the astronomy departments Campbell Hall, which was recently demolished and rebuilt on the same site.

Harold was truly a giant in our department of astronomy, UC astronomy Professor Alex Filippenko said after Professor Weavers April 26 death. I will always remember his warm smile, his generosity, and how he kept going with his research and other activities well into old age.

Professor Weaver had long served as treasurer both of the American Astronomical Society and Astronomical Society of the Pacific, and was a member of the group that founded the Chabot Space and Science Center in Oakland, where he served on the board of directors for many years.

He was also interested in contemporary writing, and for many years served as treasurer and a director of the Squaw Valley Community of Writers, a summer creative writing project located near Lake Tahoe.

The Weavers have donated their longtime Kensington home to UC to be used after their deaths to fund the Trumpler-Weaver Endowed Professorship in Astronomy at UC Berkeley.

Professor Weaver is survived by his wife and three children, Margot of Tucson, Paul of Kensington and Kirk of Houston.

Memorial gifts may be made to the Cal Alumni Leadership Award in care of the California Alumni Association, 1 Alumni House, Berkeley, CA 94720.

A memorial service is being arranged.

David Perlman is The San Francisco Chronicles science editor. Email: dperlman@sfchronicle.com

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Harold F. Weaver, pioneer of radio astronomy at UC Berkeley, dies - mySanAntonio.com

Jupiter's position near Spica this year offers an excellent chance to see how planets got their Greek name asteres planetai, or "wandering stars." From February through May, Jupiter's regular eastward journey through the distant background stars is reversed by the parallax effect of Earth's faster motion. If you observe the planet every week or two, you'll see Jupiter moving away from Spica until June 10, then approaching it again until early September, after which it pulls away to the east. The SkySafari 5 app can display the path of a selected object.

Jupiter is perfectly positioned for observing this spring. As darkness falls the planet is already shining brightly in the southeastern evening sky. It crosses the sky over the course of the night and sets in the west just before dawn. And you don't have to wait for it to become fully dark before observing it the planet is bright enough to find in twilight. It's even possible to see Jupiter in broad daylight, if you know where to look.

At night, binoculars will reveal Jupiter's four largest moons waltzing around Jupiter on predictable schedules, sometimes gathering to one side or the other, and occasionally disappearing from view. A small telescope will show them more clearly, and also reveal the brown belts that make the planet look striped. A bigger telescope will let you see the Great Red Spot, a cyclonic storm that has raged for hundreds of years. When the geometry is just right, Jupiter's moons cast small black shadows while they cross the planet. You can see them, too, with a medium or large telescope.

In this edition of Mobile Astronomy, we'll tell you how to use apps to identify Jupiter, see the motions of its moons, find out when the Great Red Spot and moon shadows are visible, and even see Jupiter in the daytime! [Jupiter is a Feast for the Eyes In New Time-Lapse Animation (Video)]

In May 2017, Jupiter is sitting in the southeastern evening sky, within the constellation of Virgo. Virgo's brightest star, Spica, is about 10 degrees (an outstretched fist's diameter) below Jupiter. It's easy to tell the planet from the star. Despite Jupiter's great distance, its large globe reflects a lot of sunlight: it's second only to Venus in brightness among the planets, and it outshines every star in the night sky. By the time Jupiter sets in the west before dawn, the rotation of the sky has moved Spica upward to the left of the planet.

Jupiter will be visible in evenings for the next few months. But try to look now, while the planet is higher in the sky and shining through a thinner layer of the Earth's distorting atmosphere. By August, the planet will be sinking into the western twilight after sunset and shining through twice as much atmosphere. After mid-September, due to Earth's orbital motion, Jupiter will disappear from view while it's near the sun during solar conjuction, and then become a morning object at year-end.

Jupiter is spending this year's apparition amid the stars of Virgo, shining brightly in the southeastern sky as darkness falls, then crossing the sky to set in the west before dawn. The rotation of the night sky shifts the nearby bright star Spica from below the planet to its left. The moon passes Jupiter every month, close enough on occasion to allow finding the planet during the day.

The famous Great Red Spot (or GRS) on Jupiter is a cyclonic storm that has been raging on Jupiter for at least 185 years. A persistent spot on Jupiter was reported even earlier, by Giovanni Cassini, from 1665 to 1713 but no one is sure whether that was the same storm we see today. The Great Red Spot's oval is large enough to hold two to three, and it is visible in backyard telescopes. Jupiter rotates quite quickly once on its axis every 10 hours and the spot takes about 3 hours to traverse the planet's disk. Thus, the spot is not visible every night. A mobile astronomy app is a perfect way to find out when to see it.

Many sky-charting apps show Jupiter as a photographic image with the red spot visible, which might fool you into thinking it's always there. However, the better apps such as SkySafari 5 present Jupiter as a complete globe that rotates at the correct rate. If your app is set to the current time, it will show Jupiter as it appears in your telescope right now. But there's a catch. Jupiter is far enough away (more than 424 million miles, or 682 million kilometers) that we don't see events there in real time. The light needs time to travel all the way to Earth. It varies through the year, but right now, it's delayed by about 37 minutes. The SkySafari app has an algorithm that corrects for this, but some of the other sky-charting apps I tested did not.

In binoculars or a small telescope, Jupiter's four largest moons Io, Europa, Ganymede and Callisto become visible to either side of the planet. Their positions change nightly. A larger telescope will show the brown equatorial bands around the planet. And a good telescope will let you see the Great Red Spot. Jupiter's 10-hour rotation period causes the spot to be visible for only a few hours at a time, roughly every second evening. Use your astronomy app to find out when to look for it.

Another option is to choose an app that focuses exclusively on Jupiter. Sky & Telescope Magazine has a very good app for iOS users called JupiterMoons (developed by the SkySafari app team). It allows you to view the planet's current appearance and move forward and backward in time, in increments ranging from seconds to years. A separate page provides a list of upcoming GRS transits in local time, and another offers plenty of Jupiter facts and figures. The CalSKY website generates tables of GRS transits visible at your location, and plenty of additional information for Jupiter and the other planets.

Jupiter has more than 60 natural satellites, or moons many are small objects that have been trapped by the massive planet's gravity. The four largest moons were first observed by Galileo Galilei in 1609 using a very modest telescope. By observing the moons nightly over a period of weeks, he discovered that they were orbiting Jupiter a controversial statement in his day. Astronomers commonly refer to the big four as the Galilean moons. From closest to farthest from Jupiter, they are named Io, Europa, Ganymede and Callisto. Io is closest to its planet and moves faster than the outer ones, needing only 1.8 days to orbit Jupiter, while distant Callisto takes nearly 17 days. [Photos: The Galilean Moons of Jupiter]

Even modern-day binoculars are better than Galileo's little spyglass, so you can look for the moons yourself. Unlike the Earth's axis, which is tilted with respect to the plane of the solar system, Jupiter's axis is vertical, so the Galilean moons always appear along a straight line that runs parallel to the planet's equator. Their differing orbital speeds produce different arrangements of the moons: close together, well separated, arranged symmetrically and sometimes all clumped to the left or right (east or west) side of Jupiter. This makes it fun to check in on them from time to time. The Jupiter system runs like clockwork, so we can accurately predict events far into the future. Your app will tell you which ones are visible where you live.

It takes only a short while to notice the moons shifting in position. Your sky-charting app will have at least the four Galilean moons labeled, and perhaps some additional fainter ones. For iOS users, the Jupiter Guide app, the Gas Giants app and the Sky & Telescope app noted above all show a clear view of the arrangement of the planet and the moons, and offer a slider or buttons to alter the time. Android users should check out the Jupiter Simulator app. Unlike binoculars, most telescopes will invert or mirror image your view of Jupiter. Some of the apps allow you to select the mode that matches your equipment. Because the moons seldom line up symmetrically, it's simple to compare what you are observing in your eyepiece with the app, and configure the flip buttons until it's the same.

Our line of sight to Jupiter also means that the moons can transit (or cross) the planet; disappear or emerge from behind it (called occultations); or even pass in front of one another. Just as our moon is eclipsed when it passes through Earth's shadow, Jupiter's moons can blink off and on as they enter and depart its shadow. Depending on the geometry of Earth, Jupiter and the sun, the appearances and disappearances happen well away from the edge of Jupiter. They only take a few minutes, so they are great events to watch through a backyard telescope.

Jupiter and its moons present a number of interesting phenomena. Moons can darken or disappear from view as they enter the shadow of Jupiter or another moon, then reappear some time later. Moons can also pass in front of Jupiter, casting their shadows on the planet, or one another, making them appear to merge for a few minutes. Astronomy apps and online resources list the times of the events.

While the moons themselves are difficult to see while transiting Jupiter, their little round, black shadows are easy to see in a decent telescope. You just need to know when to look. The moons and their shadows take hours to cross Jupiter. Transits near Jupiter's equator last up to 3 hours, while high-latitude events are shorter. Use the app to find out the start and end time for each event. Remember that your telescope may flip or invert the view that the app shows. Other than SkySafari 5, most of the above apps will not show you the shadows on the planet, but if your app says that a moon is transiting, it's worth looking for a shadow. When planning to observe, you can run the time forward on the app to discover when the other types of events will be occurring. [Jupiter Quiz: Test Your Jovian Smarts]

If you tap the Info icon in SkySafari 5, it will present a list of upcoming Jupiter moon and Great Red Spot events, complete with quick links that show how they will look. Just tap the clock icon and then zoom the display to see Jupiter's disk and the moons.

On very special occasions, two or even three shadows can be transiting at the same time! These are worth setting the alarm for. On Thursday (May 11), starting at 9:59 p.m. EDT (0159 on May 12 GMT), Europa and Io will both have shadows on Jupiter for about 6 minutes. Europa's shadow will already be transiting as the sky darkens. And after the double-shadow event, Io's shadow will continue alone until midnight EDT.

On May 18, starting at 11:53 p.m. EDT (or 0353 on May 19 GMT), the shadows of Europa and Io cross again, this time for 49 minutes.

On May 26, at 1:47 a.m. EDT (0547 GMT), the same pair of shadows will cross for 72 minutes, but Jupiter will be very low in the western sky for observers in the Eastern time zone.

Jupiter's four Galilean moons frequently cast their dark round shadows on the planet. Your astronomy app or online resources can tell you when to look for them. On rare occasions two, or even three, shadows cross at the same time, such as this event on May 18. Europa's shadow (at right) will start to transit about 10:15 pm EDT. Io's shadow will join it for 47 minutes starting at 11:53 pm. Only a very large telescope will show the moons themselves.

There are online resources to track Jupiter phenomena, too. Los Angeles' Griffith Observatory provides a list of the Jupiter moon events on this page. The events and times are provided for the Pacific Time zone, but you can add or subtract the appropriate number of hours to correct for your own time zone. If you don't live in the Pacific Time zone, some of the events listed will not be visible for instance, if the sun has not yet set, or if Jupiter has already set where you live. Conversely, some additional events will be visible only in your time zone. (This is the advantage of using a mobile app tied to your location.)

Jupiter is easily bright enough to see in broad daylight, if you know where to look. Fortunately, the moon passes Jupiter every month, and often sits close enough to make spotting Jupiter fairly easy. To the naked eye, the planet is a bright pinprick of light, but binoculars or a telescope will reveal it as a small pale disk. This month it is rising at 5:30 p.m. local time, only 3 hours before sunset. But you can use the method I give below any time the planet is well separated from the sun. Make a point of trying it this summer and fall, when it's high in the sky during the afternoon. Remember: Never point binoculars or a telescope anywhere near the sun.

Below is a list of upcoming dates when the moon is close to Jupiter. Set your app to show the date indicated and center the view on the moon or Jupiter. Alter the time to see when they are close together, and also fairly high in the sky. Zoom in on the app's display so that the moon is large enough for you to estimate how many moon diameters apart they are. Finally, make note of what direction you will need to scan starting on the moon and moving toward Jupiter. Once you're outside, bring the moon into sharp focus in your binoculars, and then search in the correct direction, hopping by the number of moon diameters you noted. Try these dates:

Jupiter and Venus are both bright enough to see with naked eyes and binoculars in the daytime, if you know where to look. On May 7, the nearly full moon will pass only 1.75 degrees, or 3.5 moon diameters, from Jupiter. Focus your binoculars on the moon, and then scan to the right, counting moon diameters as you go. Once you see the planet, try to find its bright pinprick of light without the binoculars.

On May 7, the waxing full moon is about 3.5 moon diameters from Jupiter.

On June 3, the waxing gibbous moon is about 3 moon diameters from Jupiter.

On July 28, the waxing crescent moon is about 4 moon diameters from Jupiter.

On Dec. 14, the waning crescent moon is about 6 moon diameters from Jupiter.

When the moon isn't available, you can try enabling your device's gyro and compass sensors and use the app to show you where in the sky to scan for Jupiter. It's harder but doable. Venus is also observable using the same methods.

In future columns, we'll tour the southern skies not visible from the Northern Hemisphere, suggest some spring binocular objects, talk about galaxy types and more. Until next time keep looking up!

Editor's note: Chris Vaughan is an astronomy public outreach and education specialist, and operator of the historic 1.88 meter David Dunlap Observatory telescope. You can reach Chris Vaughan via email, and follow him on Twitter @astrogeoguy, as well as Facebook and Tumblr.

This article was provided by Simulation Curriculum, the leader in space science curriculum solutions and the makers of the SkySafari app for Android and iOS. Follow SkySafari on Twitter @SkySafariAstro. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

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How to See Jupiter by Day and its Moons by Night using Mobile Astronomy Apps - Space.com

Scientists found a wave of hot gas twice the size of the Milky Way in the Perseus galaxy cluster that they believe is billions of years old.

The study, which is published in the June 2017 issue of Monthly Notices of the Royal Astronomical Society, combined data from NASAs Chandra X-Ray Observatory with radio observations and computer simulations.

Perseus, named after its host constellation, is 240 million light years away and is made of gas burning so hot it can only glow in X-rays. While studying the burning gas, Chandra found many interesting things, but focused on an enigmatic concave called the bay.

After combining 10.4 days worth of high-resolution Chandra data with 5.8 days of wide-field observations, the team had created an X-ray image of the gas in Perseus. They then filtered the data to highlight the more subtle details and compared the enhanced image to computer simulations of merging galaxy clusters.

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Scientists found a wave of ultra hot gas bigger than the Milky Way - Astronomy Magazine

Yesterday, NASAs Cassini spacecraft entered its second of the 22 dives and scientists are excitedly waiting for the data to get a second look at the rings after the surprising information from the first dive: there appears to be no dust in the area.

With this revelation, the Cassini team is continuing on with their original plan for further observations. Though now the team can ignore their plan B and wont have to worry about dust affecting the instruments.

The region between the rings and Saturn is the big empty, apparently, Cassini Project Manager Earl Maize of NASAs Jet Propulsion Laboratory said in a press release. Cassini will stay the course, while the scientists work on the mystery of why the dust level is much lower than expected.

Having no other spacecraft pass through Saturns rings before, the team had prepared for a dusty environment in the 1,200-mile (2,000-kilometer-wide) area, planning to have Cassini use its round antenna as a shield.

When Cassinis Radio Plasma Wave Science (RPWS), the instruments in the shield that detect dust, detected a very small amount, scientists switched the data to audio format. Expecting to hear the pops and cracks of dust hitting the RPWS, the team was surprised to only hear the squeaks of Cassini diving through the rings.

It was a bit disorienting -- we werent hearing what we expected to hear, said William Kurth, RPWS team lead at the University of Iowa, Iowa City. Ive listened to our data from the first dive several times and I can probably count on my hands the number of dust particle impacts I hear.

After assessing the data, the team believes Cassini only encountered a handful of dust particles no bigger than 1 micron across. Cassini is scheduled to reconnect today after its second dive yesterday.

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Cassini encounters the 'Big Empty' during its first dive - Astronomy Magazine