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Astronomy - Celestron

NASA/JPL

It commenced with a press conference, streamed onto the Internet, featuring a rock star, a filmmaker, and a cosmologist. On December 3, 2014, at the Science Museum in London, Brian May, astrophysicist and Queen founder and guitarist, Grigorij Richters, producer and director of the film 51 Degrees North, and Lord Martin Rees, Astronomer Royal of England, made an announcement.

They asked for global participation in Asteroid Day,an event to be held June 30, 2015, the 107th anniversary of the Tunguska event, an explosion caused by an incoming asteroid or comet that flattened more than 2,000 square kilometers of forest along the Podkamennaya Tunguska River in central Siberia. Asteroid Day is thus intended to raise awareness over the threat from Earth-crossing asteroids. They read a declaration about the danger our planet faces from impacts by small solar system bodies, a document signed by 100 important scientists, astronaut-explorers, entrepreneurs, and celebrities. They described activities that will take place next June to further raise awareness.

Asteroid Day

The idea originated several weeks beforehand, at the Starmus Festival in the Canary Islands. There, Richters, German-born and a resident of London, screened his film, which portrays events leading up to an asteroid impact in London, a film that was enthusiastically received and featured musical contributions by May. Richters also had the idea, along with his friend, photographer Max Alexander, to assemble a movement that would lead to Asteroid Day.

In terms of disclosure, I was a speaker at the Starmus Festival, sat in the front row to watch 51 Degrees North,and enjoyed it very much. I was even present at a dinner on the summit of La Palma, during the festival, when Richters and Alexander raised the issue of an Asteroid Day and began talking about it as a hypothetical event. And that made what was to come even more absorbing.

The press response to the Asteroid Day announcement was spectacular I think, fair to say, beyond anyones expectations. Although it should be said that whenever Brian May does something, it certainly attracts attention, and the same could also be said of Martin Rees, who is one of the most brilliant people on the planet. The announcement found itself plastered throughout numerous newspapers and online media the world over. The attention was explosive, and certainly was also helped from the inclusion of two ex-astronauts, Ed Lu and Rusty Schweickart, under whose guidance the B612 Foundation has tackled the asteroid threat. This forward-looking organization focuses on the asteroid impact danger and proposes a future Sentinel mission to thwart a potential large space rock with Earths name on it. They were also joined by the ubiquitous Bill Nye, president of the Planetary Society, who did an excellent job of explaining the realities of asteroid impact dangers.

The Asteroid Day crew, a loose assemblage of folks helping the hard-working Richters, established a website, http://www.asteroidday.org.

Get ready for ASTEROID DAY

As the mission of Asteroid Day moved toward producing educational content and fleshing out plans for the summer of 2015, reactions to the announcement and the subsequent publicity began trickling in from the community of astronomy enthusiasts. Strangely, I found the topic to be more polarizing than logic would have dictated. Massive support rolled in from many who love watching and studying the night skies after all, protecting the planet from impact is a good thing. But another contingency struck out in social media posts, on blogs, and elsewhere, sometimes even angrily accusing the movement of exaggerating the possibilities of death from the skies. In a world increasingly dominated by 140-character tweets, I found lots of hearsay and accusations washing back and forth with little substance or real understanding.

The question arises, then: What exactly is our current best knowledge about the real danger of future impacts? To help answer this, I consulted a number of planetary scientists and read voluminous papers from others. Gradually, a clear picture of reality began to crystallize.

USGS

First, I turned to a presentation from a scientist whose work I have known for many years as being characterized by unimpeachable credibility, Paul Chodas of NASAs Jet Propulsion Laboratory (JPL) in Pasadena, California. Chodas is a leading authority on the dynamics of asteroid orbits and the impact probabilities from small solar system bodies. He is the primary creator of the orbital calculation and impact probability software used by NASA, and specifically the near-Earth object office at JPL. Chodas is, along with his colleague Don Yeomans (who has just retired), also a co-developer of the Sentry impact monitoring system, automated software that continuously scans databases of the orbits of known asteroids, checking for potential future collisions. JPLs Steve Chesley has also contributed substantial amounts of work to this project.

Chodas reminds us that just two years ago, we had two unrelated encounters with small bodies passing close to or striking Earth during the same day. On February 15, 2013, a small asteroid, perhaps measuring 20 meters across, came down over the southern Urals of Russia, barreling in at about 19 km/s, and exploded over Chelyabinsk Oblast, near the town of Chelyabinsk. With a mass greater than that of the Eiffel Tower, the asteroid exploded in an airburst, unleashing energy equal to about 500 kilotons of TNT, some 20 or 30 times the energy released in the Hiroshima atomic explosion. The enormous resulting shock wave shattered glass in the towns buildings, injuring nearly 1,500 people. Eerily, within 24 hours, 2012 DA14, a space rock about 30 meters across, whizzed past Earth at a distance of some 27,700 kilometers, some 2.2 times Earths diameter.

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Asteroid Day

Suddenly, the human race suffered its first known injuries from a small asteroid explosion, and a significant event from a small solar system body crossing Earths orbit. The two events, Chelyabinsk and 2012 DA14, which seemed intuitively connected due to timing, were not. They were separate objects on completely different orbital paths.

But these were just the latest events. Earth has a long history of impacts from other bodies in the solar system, one that is almost entirely hidden because of our planets continual resurfacing from erosion, plate tectonics, volcanism, and more. In the early solar system, Earth was struck frequently and by large objects. Most planetary scientists believe the Moon formed as the result of a very early collision between Earth and a planetesimal some 4.53 billion years ago. During the so-called Late-Heavy Bombardment, about 4.1 to 3.8 billion years ago, numerous large objects impacted Earth. The Moon, which does not hide its scars so effectively, shows this impressive battering yet today.

Most travelers to northern Arizona are familiar with Meteor Crater near Winslow, and walking the perimeter of the 1-kilometer rim makes for an interesting hike. Some 50,000 years ago, a 30- to 50-meter iron meteorite, part of the core of an asteroid, hurtled into the desert plain, striking with the force of 15 megatons. More menacingly, however, is the story of the Chicxulub Crater, a subsurface scar lying underneath the Yucatn Peninsula in Mexico. In the late 1970s, two geophysicists working for the Mexican oil giant Pemex discovered a huge underwater arc in a ring some 40 kilometers across. They soon found another arc and then discovered the feature formed a circle, suggestive of an ancient impact crater.

Near-Earth asteroid 433 Eros spans some 33 kilometers in its longest dimension. This object poses more of a threat than most large asteroids because its orbit comes close to Earths. NASA/JPL/JHUAPL

At roughly the same time, Nobel Prize-winning physicist Luis Alvarez, along with his son Walter and other collaborators, had stumbled into a shock. They found evidence of a massive impact on Earth coinciding with the boundary between the Cretaceous and Paleogene geological eras, some 66 million years ago. The Alvarez team discovered high levels of iridium and osmium, and four years later scientists found shocked quartz and microdiamonds associated with an extraterrestrial impact. This coincided with the disappearance of the dinosaurs, and the K-Pg Impact (first called K-T before the redoing of geological nomenclature) was held responsible. Moreover, geological evidence ties the Chicxulub Crater with the impact, giving geologists a place on Earth where the impactor struck. This was no small rock, either, but a roughly 10-kilometer asteroid.

Two other recent events gave planetary scientists pause. In 2008, for the first time, astronomers discovered a small asteroid that was heading toward Earth, before it impacted. Designated 2008 TC3, the tiny space rock was a 4-meter-wide object weighing some 80 tons that Richard Kowalski of the Catalina Sky Survey near Tucson found on October 6 of that year. A day later, the small rock hurtled into Earths atmosphere and exploded over the Nubian Desert in Sudan. Enthusiasts and scientists recovered more than 600 meteorites collectively weighing some 10.5 kilograms and named the fall after the nearby desert railway station Almahatta Sitta.

Just five years later, on New Years Day 2014, Kowalski again discovered a small asteroid, 2014 AA, some 2 to 4 meters across, bound for Earth. Some 21 hours after discovery, the small rock entered Earths atmosphere somewhere along a line between northern South America and western Africa, quite probably into the ocean. The small number of observations didnt allow calculating a precise point of impact.

Catalina Sky Survey/University of Arizona

Close passages of asteroids to the Earth-Moon system occur frequently. The latest by a large asteroid, that of 2004 BL86, took place January 26, 2015, when this 300-meter space rock, a binary system, passed 1.2 million kilometers from Earth, about three times the distance between Earth and the Moon. According to physicist Mark Boslough of Sandia National Laboratories in New Mexico, an asteroid the size of the Chelyabinsk impactor, around 20 meters across, passes within geosynchronous orbit every two years, and within the Moons orbit nearly once a week. A Tunguska-sized (40-meter) object passes within the lunar distance from Earth several times a year.

This illustration shows the orbits of all of the so-called Potentially Hazardous Asteroids those bigger than 140 meters across that come close to Earth known in early 2013. NASA/JPL-Caltech

Asteroid impact expert Alan Harris, now retired from JPL, estimates that 200 million objects equal to or greater than 6 meters across are in Earth-crossing orbits. Harris, in fact, is the one who has produced population studies, most recently in 2012 and 2014, that have been quoted and used by Chodas and others. According to Harris, objects 6 meters or larger across strike Earth about once every two years. Roughly 10 million Chelyabinsk-sized objects are in Earth-crossing orbits and the impact interval is closer to 50 years.

The system of discovery used by Kowalski and his colleagues, the Catalina Sky Survey, is one of the primary tools employed by NASA to search for near-Earth objects and to create a list of so-called Potentially Hazardous Asteroids that could impact Earth. The first stage in assessing the threat of asteroids to Earth is to create a full inventory of near-Earth objects so that astronomers know whats out there and can understand their orbits as carefully as possible. In 1998 the U.S. Congress issued a directive to NASA to discover and track at least 90 percent of near-Earth objects of 1 kilometer or larger in diameter. A further directive in 2005 ordered NASA to identify potential impactors of 140 meters or larger.

The Catalina Sky Survey is headed by Staff Scientist Eric Christensen and Senior Staff Scientist Steve Larson of the University of Arizonas Lunar and Planetary Laboratory. The survey telescope is a 0.8-meter Schmidt camera located on Mt. Bigelow in the Catalina Mountains just north of Tucson. Further, the 1.5-meter telescope on Mt. Lemmon, also in the Catalina Mountains north of Tucson, is used as both a discovery and a follow-up instrument.

The Japanese spacecraft Hayabusa landed on the near-Earth asteroid 25143 Itokawa in 2005 and returned samples to Earth in 2010. Itokawa measures just 0.5 by 0.3 by 0.2 kilometers across, but such a space rock still could cause continent-wide devastation. JAXA

The Catalina Sky Survey is not alone. In Hawaii, the Pan-Starrs 1 telescope is also actively involved with near-Earth object discovery, as are the Darpa Space Surveillance Telescope and NEOWISE, a study using the Wide-Field Infrared Survey Explorer spacecraft. Additionally, the Lincoln near-Earth asteroid Research project has been a collaboration between the U.S. Air Force, NASA, and the Massachusetts Institute of Technology. Like the Catalina Survey, the Spacewatch program is hosted at the University of Arizona and uses two telescopes on Kitt Peak, Arizona, to help survey near-Earth objects. The NEOWISE survey, headed by planetary scientist Amy Mainzer at JPL, has been very productive, detecting more than 400 near-Earth objects in a relatively short period, including some 170 discoveries. Mainzer also leads a team that has proposed NEOCam, a space-based infrared telescope designed to discover and characterize perhaps the majority of potentially hazardous asteroids near Earth.

With these surveys and others underway, astronomers have discovered a large number of near-Earth objects, with more than 12,000 currently known. (Nearly all such objects are known to be asteroids, but about 1 percent are comets.) How many of these objects are relatively large? Some 868 are near-Earth asteroids larger than 1 kilometer across, and they would produce a global catastrophe if they struck Earth. Planetary scientists currently estimate that some 980 such objects ought to exist, and therefore that they know of just under 90 percent of them. Chodas and other planetary scientists stress that new telescopes with larger apertures and greater sensitivities, both on the ground and in space, will be needed to find the majority of the smaller asteroids, objects between 100 and 300 meters across.

NASA/JPL/JHUAPL

From all that astronomers have learned about asteroids over the past generation, they know that the danger from near-Earth objects is very real. On average, they estimate a Tunguska-sized asteroid will strike Earth every 500 years. An asteroid the size of the object that created Meteor Crater will enter Earths atmosphere on average every few thousand years. It should be said that the object that created Meteor Crater was an iron asteroid, and that composition enabled it to survive until it struck the ground. It was only a little larger than Tunguska in total mass. But the fraction of iron objects relative to rocky objects is small.

A civilization killer like the 10-kilometer asteroid of the K-Pg impact, the extinction event that did away with the dinosaurs, will strike on average every 100 million years. But these are averages; the next big impact could happen next year, or 100 years from now. Or 300 million years from now. Averages are numbers games and dont particularly care when the last event occurred.

The Galileo spacecraft captured this view of asteroid 951 Gaspra in 1991. Its dimensions (about 19 by 12 by 11 kilometers) make it only slightly larger than the kind of asteroid that could wipe out civilization. NASA/JPL-Caltech/Arecibo Observatory/USRA/NSF

The K-Pg impact created a mass extinction event because a 10-kilometer asteroid unleashes enough energy to cause global catastrophe. A small asteroid impact from an object a few meters to a few tens of meters across would cause a localized problem; a 10-meter object might cause a local or regional crisis. A very small rock does you no good if youre standing underneath it when it lands. An asteroid like the one that scooped out Meteor Crater or flattened the Siberian forest would cause a disaster of epic proportion if it struck a city. No one knows, and current research is investigating, whether a space rock of this size that struck the ocean would cause a far-ranging tsunami. But an asteroid of 1 to 2 kilometers in diameter though it is smaller than the dinosaur killer packs a sinister and devastating punch.

A 1- to 2-kilometer asteroid not only causes local and regional devastation, but it also strikes with such force and delivers so much energy that it casts a large amount of material far up into the atmosphere such that it comes down globally. Modelers of the resulting nuclear winter scenario believe such an impact ignites widespread catastrophic fires and blots out sunlight, permanently altering the planets ecosystem. It is this problem that wiped out the dinosaurs, who otherwise by rights should exist still today, and enabled small mammalian survivors to carry on, in need of only modest amounts of food, to evolve 66 million years later into human beings.

The 12,000 near-Earth objects now known by scientists are not the end of the story. Using work from a variety of sources and projects, Chodas estimates that something like 20,000 such objects in the range of 100 meters or larger must exist in the space surrounding Earth. In late 2014, NASA scientists released a bolide map showing 556 separate events between 1994 and 2013 when small asteroids entered Earths atmosphere, unleashing energy and resulting in a bright fireball in earthly skies. The range of sizes of these objects is believed to be from about 1 meter to 20 meters.

These 20 radar images reveal the 400-meter-wide asteroid 2014 HQ124, which passed within 1.25 million kilometers (about three times the Moons distance from Earth) of our planet June 8, 2014. NASA/JPL/USGS

And the effects of an asteroid impact on Earth vary wildly with the size of the impactor, so the data about whats out there, which is still partially unknown, becomes critical. According to Chodas, a 5-meter asteroid entering Earths atmosphere will produce a bolide with little other effect, unleashing about 10 kilotons of energy, and this type of event will happen on average every couple of years. An incoming 25-meter asteroid will produce an airburst event, unleashing 1 megaton of energy, and this will happen on average every 200 years. A 50-meter asteroid will strike Earth on average once every 2,000 years and will cause local scale devastation as it hits with 10 megatons of energy.

When asteroids are larger yet, the potential for widespread damage and deaths on Earth rises significantly. A 140-meter asteroid will impact Earth on average every 20,000 years, according to Harris, and will unleash 300 megatons of energy, causing regional scale devastation. A 300-meter asteroid will impact Earth roughly every 70,000 years, unleashing 2,000 megatons of energy and creating continent-wide devastation. A space rock twice that size, a 600-meter rock will impact Earth about every 200,000 years, impacting with 20,000 megatons of energy, and creating widespread but not global devastation.

It is the largest potential impactors, of course, that could create the biggest trouble. A 1-kilometer asteroid will impact Earth once every 700,000 years, on average, according to Chodas, impacting with the force of 100,000 megatons and causing a possible global catastrophe. Every 30 million years, on average, a 5-kilometer space rock will impact Earth, unleashing 10 million megatons and causing an event above the threshold of a global catastrophe. And as weve seen, once every 100 million years, on average, a 10-kilometer asteroid like the one that did in the dinosaurs will strike Earth, unleashing 100 million megatons of energy and causing a mass extinction.

The bottom line? A 1- or 2-kilometer asteroid will impact Earth, on average, about once every million years, and could produce a global catastrophe.

NASA/Hubble Space Telescope Comet Team

Over the past generation, physicists, astronomers, and planetary scientists have come to grips with the long-term future of Earths habitability. Once a hazy unknown, the distant future of life on Earth has now become relatively clear. The Sun is a slowly varying star and is gradually increasing its radiation as time rolls on. Set the current threat of global warming aside: If humans can survive all the other perils we face as inhabitants of a planet, increased solar radiation will ultimately kill off the human race, on planet Earth, a billion years or less from now. By that time, the Suns radiation will increase to the point where Earths oceans will boil away, and it will be game over.

But as we have just seen, many catastrophic asteroid impacts likely will occur within that time frame. Are we worried about a catastrophic event in the next 5 or 10 years? Or 1,000 years? Or 5,000? Perhaps not. But what we know about the near-Earth object population, and about the law of averages, says there is plenty to prepare for over the span of a billion years, in terms of defending our planet and our lives. We might have as many as 10 more impacts like the one that killed the dinosaurs. We might have as many as 1,500 impacts by a 1-kilometer asteroid over the next billion years, any of which could cause a global catastrophe.

The inventory of large near-Earth objects is pretty close to complete. Planetary scientists know of only 20 near-Earth asteroids larger than 5 kilometers in diameter, and its likely theyve found them all. They have found only two larger than 10 kilometers, and according to Boslough, scientists are 98 percent surethere are no others. Earth is effectively at zero risk for an impact by a 10-kilometer body, at least anytime soon, and they effectively shouldnt enter the equation.

The boulder-strewn surface of the large main-belt asteroid 21 Lutetia stands out in this view taken in 2010. ESA/Rosetta/MPS/OSIRIS Team

However, the inventory of near-Earth asteroids is not entirely complete. Chodas estimates that planetary scientists know of about 90 percent of such objects larger than 1 kilometer. They have probably discovered more than 50 percent of the near-Earth objects a few hundred meters across. The space rocks measuring between 100 and 300 meters in our neighborhood? We probably know of roughly 15 percent of them. And the smaller objects, those of a few dozen meters or smaller? Planetary scientists know of 1 percent of those or less.

So the cataloging and analysis of orbits must continue. But the near-Earth object population doesnt make up the whole story. The asteroids and comets close to Earths orbital space are not a static population. Over time, on the scales of several hundred thousand years, asteroids can migrate into near-Earth space from the more distant main belt of asteroids, the well-stocked group of space rocks orbiting between Mars and Jupiter. And far beyond the main belt, out in the vicinity of Neptune and Pluto, lies the Kuiper Belt, another huge population of icy asteroids and comets. And of course far beyond the Kuiper Belt, at the periphery of our solar system, is the Oort Cloud, an icy reservoir of perhaps as many as 2 trillion comets. Objects from the Kuiper Belt or beyond, be they comets or asteroids on peculiar orbits, could pass into the inner solar system and be on a collision course with Earths orbit, too.

The risk to Earth from impacts is clearly significant from the near-Earth object population, present but much less likely from the main belt of asteroids, and possible but unlikely from the Kuiper Belt and beyond. The risk certainly lessens greatly with greater distance from Earth. According to planetary scientists Hal Levison and Luke Dones of the Southwest Research Institute, the risk from the Kuiper Belt or the Oort Cloud is an order of magnitude, and possibly two orders of magnitude, less than from closer asteroids.

Moreover, Boslough raises the question of a particularly menacing population of small objects. Many amateur astronomers recall the exciting days in 1994 when backyard telescopes revealed dark blotches in the cloudtops of Jupiter, caused by the infalling pieces of Comet Shoemaker-Levy 9. Small objects whose orbits have evolved can fall into Earth with little or no warning, as was the case with Chelyabinsk. Boslough calls these objects death plungeasteroids and warns that we need a much better system of detecting potentially large numbers of these objects that could strike Earth more quickly than humans could devise a way to deflect them. Surveys should be extended to find all such objects like 2008 TC3 and 2014 AA, he suggests.

A first strike at such an early warning system will go live this year when ATLAS, the Asteroid Terrestrial-impact Last Alert System, comes on line. This project is being developed by the University of Hawaii and funded by NASA, and will consist of two telescopes, separated by 160 kilometers, designed to provide a one-day warning of a 30-kiloton town killerasteroid, a weeks warning of a 5-megaton city killer,and three weekswarning of a 100-megaton county killer.

The best-studied asteroid is the main-belt object 4 Vesta, which NASAs Dawn spacecraft orbited for more than a year in 201112. Although Vesta likely will remain in place throughout the solar systems history, some main-belt objects can be nudged onto Earth-crossing orbits. NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The risk from asteroids impacting Earth and causing widespread damage, death, and catastrophe is real, and is present every day of our lives. But it is to a degree a counterintuitive threat, which makes it hard for some people to take seriously. The risk at any given moment is almost nonexistent, but given enough time, a catastrophic event will happen again. Do we need to worry about an asteroid strike during our next foray out to lunch? Probably not. But someday a large enough asteroid with Earths name on it will enter the picture, causing horror and mayhem for humanity. Unless we do something about it, that is.

Large asteroid impacts affect the entire planet, whereas smaller ones have a more localized effect. To answer the question, How often will asteroid death come to your town?, the answer is more often from a global event than from a local one. If you multiply the impact frequency by the area affected, the larger events are more frequent. That balance is changing as planetary scientists discover more bodies, but the fact remains that the risk is still slightly greater from the remaining undiscovered big objects than from the small ones.

Understanding the risks from asteroid impacts on Earth is a pretty young exercise, as is the case with much of astronomy and planetary science. We now know that future dangerous impacts will happen, though they may be many years away. From a planetary scientists view, however, it would be grossly negligent to avoid completing as thorough a survey as possible of all the space rocks in Earth-crossing orbits and understanding other small bodies farther out in the solar system that could come our way.

It is an insurance policy for planet Earth. We should not be alarmed as concerned human beings. But we should be determined, informed, and on the clock, keeping track of the solar system and its movements. One day they will interact again in a big way with our planet. Perhaps we will discover incoming asteroids and be able to divert their orbit before disaster strikes. We damn sure will want to be ready when that day comes. Anything less would be a reckless misuse of the knowledge our species has worked so hard to gain.

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Asteroid threat realities (Astronomy ... - Astronomy Magazine

Welcome to our new, terrifying reality: According to reports, President Donald Trumps administration has ordered a media blackout of people who work at the Environmental Protection Agency and the United States Department of Agriculture.

It gets worse: According to Reuters, Trump has also ordered the EPA to remove its climate change pages.

I want to be very careful here. The EPA and USDA media blackouts might be due simply to Trumps transition team trying to minimize confusion during the changeover to the new administration; Maggie Koerth-Baker at FiveThirtyEight makes this case.

This may be true. BuzzFeed and the Associated Press, however, obtained internal emails from the EPA and USDA that indicate the new administration is gagging people at the two government agencies, forbidding them from tweeting, going on any social media, or issuing press releases about their science. The only news they are allowed to issue must be vetted first. Also, in the case of the EPA, a Trump administration order has frozen grants and any new business. Note that the EPA has been under heavy attack by the GOP for years.

For what its worth, the USDA has disavowed the order kind of. They say, This internal email was released without Departmental direction, and prior to Departmental guidance being issued. ARS [Agricultural Research Service] will be providing updated direction to its staff." So theyre not saying it wasnt true or wasnt issued, theyre just saying that it wasnt issued officially. Well see soon how this will play out. Update, Jan. 25, 2017, at 16:30 UTC: After the public outcry, the USDA has rescinded the gag order. BuzzFeed has the story.

Update, Jan. 25, 2017, at 22:00 UTC: The Trump administration has told EPA employees to "stand down" and not take down the climate change pages. This is potentially great news, but I will take it with a grain of salt: Doug Ericksen, a Washington state senator and climate change denier, is part of the transition team for the EPA and has been quoted as saying, "Were looking at scrubbing [the climate section of the EPA site] up a bit, putting a little freshener on it, and getting it back up to the public." Given that Erickson doubts climate change even exists, that statement fills me with little confidence.

Suppressing science must not stand.

On their own, under different circumstances, Id wager Koerth-Baker is right, and these emails indicate the normal sort of transitional time where its best to make sure everyone is on the same page before talking to the media. But the context here is important. The EPA has had its grants frozen, and it seems that Trump has indeed ordered them to take down their climate pages.

This also comes just days after the National Park Service Twitter feed posted a side-by-side comparison of Trumps inaugural gathering versus President Obamas; shortly thereafter the entire Department of the Interior Twitter feed went dark, allegedly on the order of the new administration. Its well-known how fragile Trumps ego is, and its being reported that he was apoplectic over media coverage of the low attendance at his inauguration and the much larger Womens March the next day (full disclosure: I marched in Denver).

Also, while Obamas White House website talked about climate change, that part of the site is now gone (it currently only exists in archival form). The new website makes no mention of it at all, except to talk about Trumps policy of opening up as much oil drilling in the United States as he can.

Given all this, it provides background into the EPA and USDA emails that is chilling. It appears that Trump wants to keep these groups under the thumb of the White House, and to make sure the only news that gets out aligns with what the new administration approves.

If true, this is no media blackout. Its censorship.

Again, this seems like an extreme conclusion, but we now live in a time of extreme circumstances. Just days ago we saw Press Secretary Sean Spicers first press meeting, where he blatantly lied about the size of Trumps inauguration audience, then abruptly left without taking questions. Then Trump spokeswoman Kellyanne Conway dismissed criticism of Spicer, saying he was presenting alternative facts.

Right. This forehead-slapping revelation prompted me to tweet:

To be clear, what Conway and Spicer were doing was lying.

The trend here is clear. Trump has been lying and saying provably false things since the early days of his campaign; his entire rise to the top of the GOP presidential candidate heap was based on his birtherism. He has also fervently denied any science that goes against his ideology, picking and choosing what he wishes to believe (or disbelieve). Hence his denial of the reality of human-induced climate change and his courting of the worst of the anti-vaccination promoters like RFK Jr. and Andrew Wakefieldthe latter is the father of the modern anti-vax movement, even though he has been struck off the U.K. General Medical Councils register and his original findings have been retracted and branded as fraudulent.

Ordering the EPA to take down its climate change pages is appalling. As Reuters says,

So yeah, thats very, very worrisome.

As bad as this is, I have no doubt whatsoever it will get worse. The National Oceanic and Atmospheric Administrationour chief scientific agency tracking climate changehas been under constant attack for years, including McCarthy-esque fishing expeditions by the GOP-controlled House Committee on Space, Science, and Technology.* NASA is also one of the strongest and most important scientific voices we have discussing climate change, and senior Trump adviser Bob Walker has already said they plan to curtail NASAs Earth science research.

How long will it be before Trump makes it official, gagging NOAA and NASA scientists as well?

Weve seen this happen before in recent times; when Stephen Harper became Canadas prime minister, his anti-science right-wing administration did much the same thing, gagging scientists, including climate scientists, from talking to the media or public. Scientists rebelled and created their own site where they could announce their results, but the gag order wasnt rescinded until Harpers party was voted out of power. Besides it being a national embarrassment, the gag order meant that news articles about scientific research could report it incorrectly and the scientists could not issue corrections. It also allowed Harper to prevent the public knowing about research that went against his own anti-climate agenda.

Dont think it can happen here? It already has, back in the George W. Bush administration, when for just one example a PR flack was put in place at NASA who meddled with their science communication efforts.

And now, it seems, its happening here once again.

This is extremely worrying. In the absence of scientific autonomy and open discussion, the administration is free to make up whatever reality serves it best. Given that Trump signed an executive order making it easier to build the Dakota Access Pipelinea colossal conflict of interest, since Trump has stock in the company that would build itwe can see very clearly what reality that will be. Massive corruption, suppression of free speech and the freedom of the press, oppression of minorities, the complete reversal of womens rights, and the literal sickening of America.

We the people need to make sure our voices are heard, and that this cannot stand. There are many ways to do this, including supporting the American Civil Liberties Union, whose sole purpose is to make sure no one tramples on the First Amendment. Also, call your senators and representative! That really can make a difference, even in heavily red or blue districts.

Make your voice heard. Suppressing science must not stand. At the very least, despite Trumps slogan of wanting to make America great again, this will hobble our countrys ability to perform first-class scientific research. At worst it will set back our ability to monitor our nations health, the quality of its products, and will also delay for years the critical need to invest in alternative energy sources (this time, the term alternative, unlike Conways claims, is actually real and beneficial) and do what we can to slow climate change.

This is a clear and present threat to our nations and our planets health. Dont let it go unchallenged.

*Correction, Jan. 25, 2017: This post originally misidentified theNational Oceanic and Atmospheric Administration as the National Oceanographic and Atmospheric Administration.

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Bad Astronomy - Slate Magazine

With the right apps installed, your phone becomes a powerful pocket toolkit for your astronomy hobby. Its GPS, compass and gyro sensors help to level and align your telescope, apps such as Astronomy Tools Night Sky provide cloud cover maps and more, and the Observer Pro-Astronomy Planner app indicates the best times to see particular objects.

The phone in your pocket is a veritable Swiss Army knife of functionality for both casual stargazers and serious astronomers. In this edition of Mobile Astronomy, we'll look at the ways your phone, when loaded with the right apps, can enhance your astronomy hobby as you plan your observing sessions, set up your telescope, record your observations and much more.

Your phone's usefulness for astronomy starts well before you pack up your telescope or cameras and leave the house. It can help you find and navigate to an observing site. It also lets you check the location's weather forecast to decide whether to make the drive.

When seeking a new dark observing site, I like to consult light pollution maps. The Dark Site Finder website uses a Google Maps interface overlaid with color-coded light pollution data. White, red and orange tones indicate extremely light-polluted areas that are poor for skywatching. Yellow means moderate light pollution, and green through black indicate the darkest skies. You can pan and zoom in and out on the map to find darker skies within a reasonable driving distance (or check the skies at your upcoming vacation spot). [A Planet Skywatching Guide for 2017: When, Where & How to See The Planets]

The Dark Site Finder website overlays worldwide light pollution data onto Google Maps. Red and white zones indicate skies with bad light pollution in urban areas while blues and grays indicate nearly pristine dark skies. The map can be zoomed and searched to find dark sky areas close to your location.

State and national parks are usually good bets for pristine skies, but you should check their after-dark policies for visitors. For privately held property, you must get permission from the owner (preferably during the daytime). They'll often be happy to host you and a few friends if you are quiet, leave the area as you found it and offer to show them a few objects.

If you are traveling to a remote location, be sure to file a "flight plan" with loved ones, and use your phone to confirm that you've arrived safely. Your stock Maps app will navigate you to a new observing site. But consider downloading the area as an offline map while you're still home, in case the cell coverage is spotty or nonexistent on-site.

Your usual weather forecasting app will tell you whether it's cloudy or clear, as well as the temperature and the chance of rain. But for observing, other factors are important, too. How steady will the air be? Rough air makes stars twinkle and blurs the view. Will the air be heavy with moisture and hazy, or dry and transparent? Will your telescope or camera become coated with dew?

The free Clear Outside app for Android and iOS provides nearly everything a skywatcher will need to know about the observing conditions. In a graphical format, it shows predicted hourly cloud-cover values, visibility (i.e., sky transparency), and the likelihood of fog, rain, wind and frost. It indicates when the sky will be fully dark after sunset and before sunrise, the contribution of moonlight, and even when the International Space Station will fly overhead!

Other favorites the free Clear Sky Droid app for Android and iCSC: Clear Sky Chart Viewer app for iOS use the popular Clear Dark Sky website. Both let you select from a list of weather station sites throughout North America. They provide an hourly breakdown, in a graphical format, of the cloud cover, transparency, seeing, darkness, wind, humidity and temperature for the next 48 hours. Note that the information is based on future weather models that are updated only about twice per day, not in real time.

The Clear Dark Sky astronomy forecasting website, developed by Attilla Danko, provides at-a-glance indicators for sky quality (seeing, transparency, cloud cover and darkness) and observing conditions on the ground (wind, humidity and temperature) for the next 48 hours for hundreds of locations throughout North America. Mobile apps such as Clear Sky Droid and iCSC: Clear Sky Chart put the site's information in your pocket.

The free Astronomy Tools Night Sky app for Android does even more than weather. It details cloud cover, sends aurora and meteor shower alerts, includes built-in light pollution maps, describes moon position, and more. The paid Scope Nights: Astronomy Weather and Dark Sky Map for iOS analyzes the weather and rates the stargazing up to 10 nights in advance, issues alerts when conditions are great, and more. For real-time weather conditions, look at the NOAA Weather Radar app for Android and iOS. It provides animated satellite imagery of cloud cover and precipitation for most of the world.

Telescopes with equatorial mounts, and most motorized GoTo and tracking systems, need to be set up level and aligned with the Earth's polar axis. The better they are aligned, the more accurate the tracking and GoTos will be. Long-exposure astrophotographs will be sharper, too. Here's how your phone can help.

At night, the polestar (Polaris, or the North Star) can be used for alignment. But if you are setting up a tracking telescope to observe the sun or a nighttime scope before it's dark enough to see Polaris or if you are in the Southern Hemisphere, where there is no polestar to align on it helps to have a compass app handy. There are plenty of free ones. You need to set up based on true north, not magnetic north. The better compass apps will include what's called a declination correction for this.

To level the telescope tripod, install a bubble level app, and simply rest your phone on the eyepiece tray or another part of the mount. Find an app that levels in two directions simultaneously, such as a circular bubble level, and that buzzes when levelness is achieved so that you can adjust the tripod legs without needing to see the phone's display.

The polar (or right ascension) axis of equatorial mounts need to be tilted at the angle equal to your latitude on Earth. Pick a bubble level app such as Bubble for Android or Bubble Level for iPhone and iPad that has a digital readout of the tilt. Then, use it to check the angle of the telescope's tube, or the polar axis directly. (For mounts that have counterweight shafts, you can hold the phone against it. The shaft should be tilted at 90 degrees minus your latitude.)

Remember that your device's compass and gyroscope need to be calibrated properly. Bubble level apps have options to zero the reading when your phone is resting on a horizontal surface. Compass apps will have instructions to sweep your phone in a pattern that corrects the magnetic readings. Be sure to avoid standing near metal objects, such as your car, when doing this. Another good option is to check your phone's tilt and compass readings on a telescope that you know is already aligned, using the polestar.

Designed for hiking and other activities outdoors, the Polaris GPS Navigation App is also handy for astronomers for setting up and aligning a telescope. The app displays the position and time data from your device's GPS receiver, as well as the compass bearing.

Finally, computerized telescope mounts also need to know the correct time and observing location so that they can calculate where the stars are. Your phone's GPS sensor measures these, but there isn't always an easy way to access the values. I find that a good hiking or navigating app, such as DS Software's free Polaris GPS Navigation for Android, offers everything you'll need, including a compass. [June Full Moon 2017: How to See the Strawberry Minimoon]

In past editions of Mobile Astronomy, we've covered the many ways in which astronomy sky chart apps can help you identify things in the sky and locate particular objects. They also provide many details about these sights. Many astronomy enthusiasts like to keep a record, or observing log, of what they have seen over the years. Some chase down certain objects in order to earn observing certificates from astronomy clubs or societies, and some prefer to observe certain types of objects. (I like planetary nebulas!) There are also specific types of observations, such as variable star brightness estimates, that you can submit as a citizen scientist.

SkySafari 5, Night Sky Tools and other apps include additional functionality for creating observing lists. Set the app to the date and time you'll be observing, and use the search function to find the objects of interest. Alternatively, you might need to view a particular target in an observing certificate program. The app can show you the best time to see it.

To make an observing list in SkySafari 5, open the Search menu, scroll to the bottom and tap the Create New Observing List option. You'll be prompted for a name. Exit this menu, and select a celestial object by tapping it on the display. Tap the Info icon. (You can also do this by using the object's name in the search menu.) In the lower right of the information panel, tap the More icon. A dialog box will appear. Select Add to Observing List, and tap the list you created. Later, you can sort, edit and manage the objects in the list. You can also make multiple lists. There are also dozens of publicly available observing lists you can import from the Online Repository.

Traditionally, observations were recorded in a paper logbook. But your phone makes this far easier. You can log a description of an object using the voice recorder on your phone as you peer into the eyepiece. You can type into a note-taking app. Or, better yet, you can use an astronomy app with logging functionality.

For instance, you can log your observations of your observing-list objects in the SkySafari 5 app. In the object's information page, tap More and select Create New Observation. The app will launch a form where you can enter the date, time and location (some are autofilled), your notes, the equipment you used, and the seeing and transparency rating for the night. The Night Sky Tools app for Android provides similar functionalities, and even allows for filters or cameras.

The SkySafari 5 app includes functions to create observing lists and log observations, including the date, time, location, equipment used and sky conditions.

Finally, the Observer Pro Astronomy Planner for iOS app lets you plan your sessions, make observing lists and log observations. It even lets you map the horizon profile of your observing site to determine when objects will be visible for example, high enough to clear the neighbor's garage roof all for about $10.

Telescope owners find it helpful to know the magnifications and fields of view produced by their various eyepieces. A good tip is to calculate the values and save them in a document on the phone. Or, use an app designed just for that! The AstroAid app for iOS lets you select from preloaded commercial telescopes, eyepieces and accessories. Then, it can calculate all of the values, and even generate previews for many of the major deep-sky objects.

The AstroAid app for iOS allows you to select from a list of provided telescopes and eyepieces that match your own setup. It then generates observing previews of major deep sky targets to assist in planning your observing or astrophotography session. It can also help you decide what equipment to buy because you can experiment with different combinations of apertures, focal lengths and other parameters.

Everyone approaches astronomy their own way. When I'm not chatting with folks, I like to listen to music when I observe, and my smartphone is loaded with plenty of inspiring tracks for that. If you do the same, be sure you aren't bothering your fellow observers or disturbing sleepers in the middle of the night. For safety, avoid using earbuds when observing alone in an unfamiliar place.

You don't need to be an expert astrophotographer to capture a memento of your night under the stars. In How to Snap Awesome Photos of Night-Sky Objects with Your Smartphone, we covered how to capture images of astronomical targets using your phone. Astronomy outreach and education events are perfect opportunities to engage students and the public in astronomy by sharing their excitement and images on social media. And, hey, why not tweet or text an invitation to your next observing session? We'd love to join you!

If you have found other ways to use your phone for astronomy, feel free to send me a note or share them in the comments. In a future edition of Mobile Astronomy, we'll cover how to wirelessly control your telescope with your phone, highlight some early summer celestial treats, and more. Until then, 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 him via email, and follow him on Twitter @astrogeoguy, as well as on 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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Turn Your Smartphone into an Astronomy Toolbox with Mobile Apps - Space.com

Research | Science | Technology | UW Today blog

June 2, 2017

LIGO has discovered a new population of black holes with masses that are larger than what had been seen before with X-ray studies alone (purple).LIGO/Caltech/Sonoma State (Aurore Simonnet)

The announcement that a third collision of black holes has been detected three billion light years away validates the work of hundreds of scientists, including teams at the University of Washington and UW Bothell.

The discovery was made using a detector located at Hanford in eastern Washington and its twin in Louisiana, together known as the Laser Interferometer Gravitational-wave Observatory (LIGO). This new window in astronomy observes ripples in space and time, as predicted by Albert Einstein. The first two waves generated by the merger of two black holes were detected in 2015. The third, detected in January, is described in a paper published in the journal Physical Review Letters.

Recently, the UW teams have made a significant instrumental contribution to LIGOs second Observing Run by installing ultra-sensitive tiltmeters at the LIGO Hanford Observatory (LHO), one of the two LIGO observatories in the U.S. These tiltmeters improve the isolation of LIGO from ground motion, thus increasing the duty cycle of LHO under adverse environmental conditions, such as high wind and high ground motion.

Despite 20 mph winds on Jan. 4, the improved seismic isolation at LHO helped identify the nearly simultaneous gravitational-wave signal seen at the two LIGO observatories. Those gravitational-wave signals, which lasted less than a second in the detector, are believed to be from the merger of black holes with masses about 31 and 19 times the mass of the sun, which happened at a distance of more than 3 billion light years. Energy equivalent to twice the mass of the sun was radiated as gravitational waves.

UW Bothell students are working with scientists at the LIGO Hanford Observatory on data quality and contributing to searches for other gravitational wave sources, said Joey Key, assistant professor of physics at UW Bothell, one of the authors of the paper.

This figure shows reconstructions of the three confident and one candidate (LVT151012) gravitational wave signals detected by LIGO to date, including the most recent detection GW170104.LIGO/Caltech

LIGO is opening up a new way to explore our universe, including populations of elusive black holes, Key said. This is a significant discovery of a new black hole collision, adding to our map of black hole systems and utilizing the increased sensitivity of the LIGO detectors.

Key leads the UW Bothell LIGO Scientific Collaboration group, which includes lecturer Matt DePies and students Andrew Clark, Holly Gummelt, Paul Marsh, Jomardee Perkins and Katherine Reyes. Physics professor Jens Gundlach, graduate student Michael Ross and Krishna Venkateswara, assistant professor of physics, comprise the LIGO Scientific Collaboration group at the UW in Seattle.

With the detection of a third binary black hole merger, LIGO continues to expand our knowledge about the nature of these events, their astrophysical origins and about the fundamental nature of gravity, Venkateswara said. LIGO is allowing us to hear the sounds of the universe and many more exciting symphonies await discovery.

The UW research was funded by the National Science Foundation (NSF).

LIGO is funded by the NSF and operated by MIT and Caltech, which conceived and built the project. Financial support for the Advanced LIGO project was led by NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council) making significant commitments and contributions to the project. More than 1,000 scientists from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. LIGO partners with the Virgo Collaboration, a consortium including 280 additional scientists throughout Europe supported by the Centre National de la Recherche Scientifique (CNRS), the Istituto Nazionale di Fisica Nucleare (INFN), and Nikhef, as well as Virgos host institution, the European Gravitational Observatory. Additional partners are listed at: http://ligo.org/partners.php

For more information, contact Joey Key at UW Bothell at 425-352-5497 or joeykey@uw.edu, or Krishna Venkateswara at 301-395-8750 or kvenk@uw.edu.

Grant numbers: NSF 1607385 and 1505861.

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UW, UW Bothell scientists explain new discovery in gravitational wave astronomy - UW Today

Zooniverse is a revolutionary citizen science initiative led by Chicagos Adler Planetarium and the University of Oxford. The platform hosts a wide range of projects that allow anyone, of any age and background, to engage in current ongoing scientific research in a fun, understandable, and simple way. On May 31, Zooniverse launched its 100th project on its 10th anniversary: Galaxy Nurseries, a hunt for young galaxies in the distant universe, which were forming stars about 5 to 7 billion years ago. And the Galaxy Nurseries team has an ambitious goal complete Zooniverses 100th project in 100 hours. The clock is ticking, but theres still plenty of time left; if youre interested in exploring the early universe and lending your eye to identify these amazing objects, consider taking a little time this weekend to make some classifications of your own. Searching for young galaxies Galaxy Nurseries takes advantage of a unique dataset provided by the Hubble Space Telescope (HST) as part of the WFC3 IR Spectroscopic Parallel (WISP) survey. When searching for young, star-forming galaxies in the early universe, simply taking an image is not enough. To get more information, these images not only provide a classical picture of everything in a given field of view, but also a spectrum for every single object Hubble can spot. A spectrum is essentially the result of passing light from an object, such as a star or galaxy, through a prism, which breaks the light apart by wavelength. As the light is spread out, it gives clues about the objects nature. In particular, star-forming galaxies will show features called emission lines. Emission lines indicate material such as gas that is glowing brightly, and only hot stars are capable of producing the radiation needed to excite nearby gas enough to produce certain emission lines. Because these huge, extremely hot stars dont last very long (in the cosmic scheme of things), their existence is indicative of recent star formation. And these young star-forming galaxies are exactly what the researchers behind the Galaxy Nurseries project are after. Why? There are two main reasons behind the development of the 100th Zooniverse project. First, theres the underlying science. Claudia Scarlata, a physics and astronomy associate professor at the University of Minnesota and principal investigator of the Galaxy Nurseries Zooniverse project, explained to Astronomy that these galaxies are extreme objects that are not specifically targeted for spectroscopy in most surveys. Traditionally, obtaining spectra is harder than simply taking an image it often requires more light, and can thus be challenging for such small, faraway objects. Astronomers have sometimes gotten around this problem by classifying galaxies based on their colors in images. But these galaxies have booming [emission] lines, Scarlata said, and their colors can be changed. They are often misclassified in broadband surveys, that simply look at the color of the light coming from objects in an image. But through the WISP survey, we have a spectrum of every object in the Hubble field of view, Scarlata says. Armed with this information, these objects now have spectra that can be analyzed, helping researchers such as Scarlata and her colleagues study star formation in the distant universe. There are several questions the team is looking to answer. How are these galaxies forming stars over time? What is their environment like? Are they isolated or found in groups? Are they dusty, or not? (Current research, Scarlata says, indicates the latter.) What type of metals (elements heavier than hydrogen and helium) do these galaxies have? Averaging a large number of objects can give you the numbers you need, Scarlata says, to start characterizing these young galaxies, which have been previously studied only in very small samples. But, Scarlata says, there will be contaminants, such as active galactic nuclei, Milky Way stars, and even gravitational lenses. The goal of Galaxy Nurseries is to screen out these contaminants by showing volunteers what to look for, then letting them loose on the most promising data to determine whether the detection is real or spurious. But even these contaminants hold scientific value. While the initial goal of Galaxy Nurseries is to identify these young galaxies, Scarlata says that volunteers will undoubtedly find new and strange objects during the search. Were also looking for the unexpected, she says, and we will follow up on everything, even if its not the galaxies were looking for. Improving how science is done The second reason Galaxy Nurseries is so important is the potential it holds to make searching for galaxies and other scientific objectives and more accurate in the future. Specifically, there are two upcoming missions that will use similar techniques to find objects of interest: the NASA/ESA Euclid mission and NASAs WFIRST telescope. The work that volunteers put into Galaxy Nurseries, Scarlata says, will help us determine what works, what doesnt, and where the volunteers are needed most. For example, Euclid will gather similar data, but WISP has covered something like half a degree of the sky. Euclid will look at 15,000 square degrees thats an area 30,000 times larger than WISP, she says. Thus, the information gained from Galaxy Nurseries and the other projects hosted on Zooniverse will pave the way for not only better machine learning to increase real detections in these larger datasets, but also improve projects ability to utilize citizen science volunteers even more efficiently and beneficially in the future. Thats the magic of Zooniverse, says Michelle Larson, the president and CEO of the Adler Planetarium. Zooniverse continues to push itself. Its about scientific progress. As volunteers put their time into the various projects offered, it allows researchers and software developers alike to improve upon the aspects of science that machines can handle, as well as continually zooming in on the tasks that only humans can perform. Coming full circle Galaxy Nurseries is also a fitting 100th project for Zooniverse. The origin of the Zooniverse platform itself lies in the Galaxy Zoo project, launched in 2007. Thus, a 100th project brings the concept full circle; Were going back to the origin. It started with galaxies, and now its coming back to galaxies, Scarlata says. Galaxy Zoo was born from the need to parse through a huge volume of data in a reasonable way, which would have been unfeasible for one person or even several working together. And the response was overwhelming, Chris Lintott, an astronomer currently at the University of Oxford who is the co-founder of both Galaxy Zoo and Zooniverse told Astronomy. Galaxy Zoo was not supposed to still be running 10 years later, Lintott says. But it is and Zooniverse projects have been responsible for some amazing discoveries, including Hanny's Voorwerp and an exoplanetary system with four super Earths. And, if youve read about the third successful detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) thats currently topping science news, you might also be interested in checking out another Zooniverse project: Gravity Spy, which allows citizen scientists to help gravitational wave researchers filter out glitches in the data so that real signals can be found more easily. Zooniverse projects have produced over 100 peer-reviewed science publications, and there are currently more than 1.5 million registered users from around the world participating in projects that largely focus on astronomy, but also include biology, climate science, history, language, literature, medicine, and animal behavior. Whether you want to find exoplanets, count wildebeest in the Serengeti, or further research on cellular structure, theres a Zooniverse project for you. Zooniverse is inclusive, stresses Lintott. Its about discoveries we can make together.

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Are you ready to find baby galaxies? | Astronomy.com - Astronomy Magazine

When stars are swallowed by a supermassive black hole, do they go out like a candle or crash into a solid surface? The first option upholds general relativity as is, while the second relies on a modified version of this famous theory. Now, a group of astronomers has found a way to study what happens at a black holes event horizon, even though there are no images of this region of space. Their findings? General relativity is safe.

Pawan Kumar of The University of Texas at Austin, along with his graduate student Wenbin Lu and colleague Ramesh Narayan of the Harvard-Smithsonian Center for Astrophysics, found a unique way to determine just what happens to stars as they approach extremely massive objects i.e., black holes. Their results are published in Monthly Notices of the Royal Astronomical Society.

Nearly every galaxy in the universe, including our own, has a central massive object at its center. These massive objects are assumed to be supermassive black holes several millions or even billions of times the mass of our Sun. This is because according to general relativity, objects of a certain mass cannot be held up by any known force, and thus collapse into black holes.

Black holes are singularities with no physical surface area, surrounded by an event horizon. The event horizon acts like a one-way membrane material can fall in toward the black hole, but once it passes the event horizon, it can no longer send out light that is visible to the rest of the universe because the gravity of the black hole pulls the light back toward itself. Once past the event horizon, the material, in essence, disappears from view.

But what if general relativity isnt quite right? What if, instead, these central massive objects arent collapsed down to a point? If that were the case, the event horizon would have different properties. Kumar and his colleagues theorized that if the central massive object is not a black hole, then the event horizon would not act like a one-way membrane, but like some kind of solid surface against which any infalling material would smash. This would produce a visible effect as the infalling stars gas lit up as a result of the collision, enveloping the massive object and glowing visibly for months or even years.

Our whole point here is to turn this idea of an event horizon into an experimental science, and find out if event horizons really do exist or not, said Kumar in a press release announcing their results.

To test these competing ideas, the team turned to observations taken with the 1.8-meter Pan-STARRS telescope in Hawaii over the course of 3.5 years. By calculating how many stars should fall onto supermassive black holes in the nearby universe, the group could determine how many events they should see over the course of the 3.5 years the survey was active. If they saw signs of this theorized glow, it would signal that the event horizon was solid; if not, it would mean that general relativity is correct, and stars simply pass the event horizon and go dark.

Given the rate of stars falling onto black holes and the number density of black holes in the nearby universe, we calculated how many such transients Pan-STARRS should have detected over a period of operation of 3.5 years. It turns out it should have detected more than 10 of them, if the hard-surface theory is true, explained Lu.

Why is there any debate at all? Currently, telescopes are not able to resolve the region immediately around a compact object to directly observe the event horizon and its properties. But astronomers are continually pushing the boundaries of their instruments, seeking better, closer-in images of black holes.

The Event Horizon Telescope, a combination of several observatories, made its first observations of the area surrounding a supermassive black hole in April, though these data are still undergoing image processing and evaluation.

The Large Synoptic Survey Telescope, currently under construction, will perform surveys like those taken with the Pan-STARRS telescope, but with significantly greater sensitivity to events like the glow that would be left behind by collisions with a solid surface event horizon.

Because of this lack of direct evidence, the event horizon has remained mysterious in nature. And according to Kumar, Our motive is not so much to establish that there is a hard surface, but to push the boundary of knowledge and find concrete evidence that really, there is an event horizon around black holes.

After poring through the data returned from the Pan-STARRS telescope, Kumars group found no afterglow signature of any collisions.

In this case, a lack of signal is a good thing, if you support general relativity. Said Narayan, Our work implies that some, and perhaps all, black holes have event horizons and that material really does disappear from the observable universe when pulled into these exotic objects, as weve expected for decades. General relativity has passed another critical test.

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How do stars die when they fall into a supermassive black hole? - Astronomy Magazine

ALBERT LEA An Albert Lea High School educator is determined to spread the word about a total solar eclipse that will confuse nature at the end of summer.

On the first day of school this coming fall, Ken Fiscus, an earth and energy science teacher, will not be in school. He will be en route to a better view of the Great American Eclipse.

It is finally here, Fiscus said. The educator has not seen a total solar eclipse in 19 years.

Fiscus will travel to Pawnee County, Nebraska, where he grew up, to feast his eyes on the solar event at 1:03 p.m. Central Time on Aug. 21.

The 2017 total eclipse will only be visible for two minutes and 35 seconds.

A total eclipse, as Fiscus explained Tuesday night at the ALHS auditorium to a group of astronomy enthusiasts, is when the sun is completely blocked by Earths orbiting moon. This happens when the moon passes between the Earth and the sun at the exact right moment and angle, thereby totally or partially blocking someone on Earths view of the sun.

A total eclipse has not been visible from the United States since 1998 and after the Aug. 21 event, a total eclipse will not be visible again from the United States until 2024, Fiscus explained.

Fiscus has only seen two other total solar eclipses in his lifetime as an astronomy enthusiast. He traveled to Mexico in 1991 and Aruba in 1998 to see the rare events.

Albert Lea and its surrounding communities will not be as greatly affected by the solar event as some other Americans.

A total eclipse can only be seen from a certain strip of the United States. The strip is about 70 miles wide and will stretch from Oregon on the West Coast to South Carolina on the East Coast.

The closer people travel to the center of the strip, the darker the sky will become and the more vibrant and longer the eclipse will be, Fiscus said.

In Albert Lea, Fiscus explained that on the day of the total eclipse, the sky will be an odd blue color that people have not seen before. He said colors will seem more saturated in natural light, shimmering lines will cover the ground, contrast will be greater to the eye, shadows will be extremely crisp and the temperature will drop.

During a total eclipse, daytime instantly becomes a dark twilight and only the suns rays, or corona, is visible. The darkness that falls over the Earth during a total eclipse travels at the speed of a bullet, Fiscus said. The corona, or crown of the sun, shimmers bright in the night sky.

Fiscus explained that the sky in Albert Lea will not be as dark as certain parts of the country.

This instant darkness confuses nature Fiscus said he hopes someone brings a rooster to the event so he can hear a rooster crow in the middle of the afternoon.

Animals and people alike will be astounded by the beauty of the event, Fiscus outlined in his presentation.

During the total eclipse that Fiscus witnessed in Mexico in 1991, Fiscus said that even the dolphins surrounding the cruise ship were confused by nature. In Aruba in 1998, divers specifically traveled to the eclipse event to watch the state of confusion for animals underneath the surface of the water.

There are different types of eclipses, Fiscus said, however, the total eclipse is the most rare.

More information about the eclipse or traveling to view the eclipse can be found at eclipse2017.org.

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Astronomy enthusiast gears up for total solar eclipse - Southernminn.com