'Golden Record 2.0': New Horizons Probe Could Carry Digital-Age Message for Aliens

'Golden Record 2.0': New Horizons Probe Could Carry Digital-Age Message for Aliens:

The cover of the Golden Record, copies of which launched aboard NASA's Voyager 1 and Voyager 2 probes in 1977.

Credit: NASA

NASA's New Horizons spacecraft could end up bearing a message for intelligent aliens, just as the agency's venerable Voyager probes are doing.

Both Voyager 1 and Voyager 2 famously carry copies of the "Golden Record," which are loaded with photos, music, sounds and other data designed to teach any extraterrestrials who might encounter the probes about humanity and its home planet.

Though such an alien encounter isn't likely, it is possible; Voyager 1 popped into interstellar space in August 2012, and its twin will probably do the same in the next few years, mission team members have said. [The Golden Record in Pictures: Voyager Probes' Message to Space Explained]

New Horizons' ultimate fate also lies beyond the solar system, "and it's leaving without a Golden Record, without a message," said Jon Lomberg, the design director for the Voyagers' Golden Record. (He worked closely with astronomer and science communicator Carl Sagan, who chaired the committee that decided what information the record would contain.) "That seems like a missed opportunity," he said.

Lomberg wants to change things, by giving New Horizons a "Golden Record 2.0" — a new, crowdsourced digital version called the One Earth Message, which would be beamed out to the spacecraft in 2020.

On Aug. 20 — the 40th anniversary of Voyager 2's liftoff — he and his team launched a 40-day Kickstarter campaign, which seeks $72,000 to develop and maintain a website that will manage the photos and other material people submit for possible inclusion in the One Earth Message. If all goes according to plan, online voting will determine which content will ultimately make up the message.

Jon Lomberg's original sketch for the cover diagram of the Voyager mission's famous "Golden Record." This drawing and other golden-record archival material will go up for auction on Sept. 14, 2017.

Credit: Jon Lomberg/Heritage Auctions


The group is also seeking funding via other means. For example, Lomberg is auctioning off his collection of Voyager Golden-Record archival material, which includes (among other things) his original sketch for the cover diagram, numerous other drawings, and letters about the project from sci-fi legend Robert Heinlein and other notable people.

Heritage Auctions will manage the sale, which will take place Sept. 14. The collection is expected to fetch about $10,000, Heritage representatives told Space.com.

As such fundraising efforts suggest, NASA is not sponsoring or bankrolling the One Earth Message. However, agency officials and New Horizons team members have unofficially signaled support for the project, Lomberg said.

New Horizons, which flew past Pluto in July 2015, is now zooming toward a Jan. 1, 2019, rendezvous with a small object called 2014 MU69. It may take a year or so for the probe to beam all of its data from this second flyby home to Earth, Lomberg said; only then will New Horizons be able to spare the computer memory necessary to accommodate the One Earth Message.

"That gives us a good two years to first put the message together, which I estimate will take at least a year, and then another year to put it all together in software, test it and make sure it's suitable for upload," Lomberg said.

The upload to New Horizons would not happen without official NASA approval. This approval might be easier to obtain if the team approaches the agency with a finished product rather than a nebulous concept, Lomberg said.

"Forty years ago, when I worked with Carl on the Golden Record, he didn't go to NASA and try to get them to approve some vague idea of the message's music and sounds," Lomberg said. "He made it, and then he showed it to them and said what we did. They reacted to it. And if there was something they didn't like — and there was one picture they didn't like — they took it out."

Lomberg's vision for the One Earth Message doesn't end with New Horizons. Eventually, he would like every probe that leaves Earth to carry the message, or something like it.

"I think our spacecraft are our finest technical masterpieces," he said. "They're essentially works of art, and every work of art should be signed."

"Signing" probes in this fashion is worth the effort, even if they drift alone through space for eternity, Lomberg added.

"We will never know if there is an E.T. audience, but for the human audience that participates, it can be a profoundly moving experience to seriously contemplate communicating with the cosmos," he said in a statement.

You can learn more about the One Earth Message and its Kickstarter campaign here: https://www.kickstarter.com/projects/31060842/one-earth-message-a-digital-voyager-golden-record/description

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.

Dinosaur-Killing Asteroid Cast a 2-Year Shroud of Darkness Over Earth

Dinosaur-Killing Asteroid Cast a 2-Year Shroud of Darkness Over Earth:

Credit: solarseven/Shutterstock

The 2 minutes of darkness caused by the total solar eclipse earlier this week may seem momentous, but it's nothing compared with the prolonged darkness that followed the dinosaur-killing asteroid that collided with Earth about 65.5 million years ago, a new study finds.

When the 6-mile-wide (10 kilometers) asteroid struck, Earth plunged into a darkness that lasted nearly two years, the researchers said.

This darkness was caused, in part, by tremendous amounts of soot that came from wildfires worldwide. Without sunlight, Earth's plants couldn't photosynthesize, and the planet drastically cooled. These two key factors likely toppled global food chains and contributed to the mass extinction at the end of the dinosaur age, known as the Mesozoic, according to the study. [Wipe Out: History's Most Mysterious Extinctions]

The finding may help scientists understand why more than 75 percent of all species, including the non-avian dinosaurs, such as Tyrannosaurus rex, and large marine reptiles, such as the plesiosaur, went extinct after the asteroid slammed into what is now Mexico's Yucatán Peninsula, the researchers said.

Killer asteroid

When the space rock smashed into Earth, it probably triggered earthquakes, tsunamis and even volcanic eruptions, the researchers said. The asteroid hit with such force that it launched vaporized rock sky-high into the atmosphere. Up there, the vaporized rock would have condensed into small particles, called spherules.

When the spherules plunged back down to Earth, they rubbed against one another, causing friction and heating to temperatures hot enough to ignite fires around the world. In fact, a thin band of spherules can still be found in the geologic record, the researchers said.

Most large Mesozoic land animals died in the asteroid's immediate aftermath, "but animals that lived in the oceans or those that could burrow underground or slip underwater temporarily could have survived," the study's lead researcher, Charles Bardeen, a project scientist at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, said in a statement.

"Our study picks up the story after the initial effects — after the earthquakes and the tsunamis and the broiling," Bardeen said. "We wanted to look at the long-term consequences of the amount of soot we think was created and what those consequences might have meant for the animals that were left."

Earth without photosynthesis

Even though researchers found evidence for the asteroid in the late 1970s, there still isn't "universal agreement" on how long Earth was shrouded in darkness after the space rock smacked into the planet, Bardeen told Live Science. [Doomsday: 9 Real Ways Earth Could End]

Other researchers have estimated the soot produced by these ancient wildfires by measuring soot deposits in the geologic record. But Bardeen and his colleagues took another route: they used the NCAR-based Community Earth System Model (CESM) — a modern chemistry-climate model that factors in components related to the atmosphere, land, ocean and sea ice. This model allowed the scientists to simulate the effect of soot in the years following the asteroid impact.

"Different studies have assumed various types of particles including dust, sulfates and soot," Bardeen told Live Science in an email. "All of these particles can block enough sunlight to cool the surface, but only soot is so strongly absorbing that it is self-lofting, can heat the stratosphere and reduces sunlight at the surface light to very low levels."

Furthermore, the researchers used the most up-to-date estimates of the amount of fine soot in the geologic record — that is, 15,000 million tons.

"Our study shows it is dark enough to shut down photosynthesis for up to two years," Bardeen said. "This would have a devastating effect, particularly in the ocean, since the ocean relies upon phytoplankton as a primary source of food and loss of this would be catastrophic to the entire food chain."

Even if the soot levels had been one-third the actual amount, photosynthesis would have still been blocked for an entire year, the researchers found.

Other catastrophic effects

In addition to stopping photosynthesis, this worldwide cloud of soot would have prevented much of the sun's heat from reaching Earth. For more than a year following the crash, the land and oceans would have cooled by as much as 50 degrees Fahrenheit (28 degrees Celsius) and 20 degrees F (11 degrees C), respectively, the researchers found. [Crash! 10 Biggest Impact Craters on Earth]

In contrast, the upper atmosphere, known as the stratosphere, would have warmed because that's where the soot floated around, absorbing the sun's heat. These roasting temperatures would have depleted the ozone, and also allowed for vast quantities of water vapor to hover in the stratosphere. When this water vapor chemically reacted with the stratosphere, it would have created hydrogen compounds that led to further ozone destruction, according to the researchers.

As the ozone disappeared and the soot cleared, damaging doses of ultraviolet light reached Earth, harming life there, the researchers said.

When the stratosphere eventually cooled down, the water vapor there condensed and began raining, abruptly washing away the soot, Bardeen said. As some soot left, the air there cooled, which in turn led the water vapor to condense into ice particles, which washed away more soot.

Once this cooling cycle repeated enough times, the thinning soot layer vanished within months, the researchers found.

Bardeen credited his friend Betty Pierazzo, a senior scientist at the Planetary Science Institute, a nonprofit headquartered in Tucson, Arizona, with securing funding from NASA to do this study. Unfortunately, Pierazzo died before research on the end-Cretaceous asteroid got underway.

Bardeen also noted several limitations, including that the model is based on a modern Earth, and it's unknown whether Earth at the end of the Cretaceous period had different atmospheric properties, such as different concentrations of gases.

The study was published online Monday (Aug. 21) in the journal Proceedings of the National Academy of Sciences.

Original article on Live Science.

Great American Solar Eclipse Breaks NASA's Web-Viewing Records

Great American Solar Eclipse Breaks NASA's Web-Viewing Records:

The “diamond-ring effect” is seen during the total solar eclipse of Aug. 21, 2017. This photo was taken from a NASA Gulfstream III aircraft flying 25,000 feet (7,620 meters) over the Oregon coast.

Credit: Carla Thomas/NASA

In case you didn't notice, people were really into the Great American Solar Eclipse. I mean, really into it. Just take it from NASA.

"With more than 90 million page views on nasa.gov and eclipse2017.nasa.gov, we topped our previous web traffic record about seven times over," agency officials wrote in a postmortem on Thursday (Aug. 24). "For much of the eclipse, we had more than a million simultaneous users on our sites. On social media, we reached more than 3.6 billion nonunique users, and Twitter reports there were more than 6 million eclipse tweets that day."

NASA also estimates that its live eclipse webcast Monday (Aug. 21) got more than 40 million views, another huge number.

"The nasa.gov numbers alone are several times larger than reported streaming numbers for recent Super Bowls, putting the eclipse in the realm of major news, sports and entertainment events," agency officials wrote.

User sessions on NASA websites from May 2015-present, as measured by Google Analytics.

Credit: NASA


The excitement isn't hard to understand. The path of totality Monday extended from Oregon to South Carolina, marking the first time that a total solar eclipse had crossed the U.S. mainland coast to coast since 1918. And no total solar eclipse had even touched the continental United States since 1979.

If you missed Monday's big event, don't fret: Another total solar eclipse will darken American skies on April 8, 2024, moving northeast from Mexico to Texas and then all the way to Maine and up into Canada. Maybe that one will break some more records.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.

The Matter with Dark Matter

The Matter with Dark Matter:

The Bullet Cluster is one example of a cosmic feature that indicates the presence of dark matter, a substance that doesn't interact with light or with itself. The image combines X-ray and visible light images, as well as gravitational lensing data.

Credit: X-ray: NASA/CXC/CfA/ M. Markevitch et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/ D.Clowe et al. 
Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.

Paul Sutter is an astrophysicist at The Ohio State University and the chief scientist at COSI Science Center. Sutter is also host of Ask a Spaceman, We Don’t Planet and COSI Science Now. 

Dark matter is more than a name — it's a part of our universe. But it's totally unfamiliar to our everyday experience. Based on the evidence, scientists think it's invisible in the truest sense of the word: It simply doesn't interact with light. Gravity, however, is universal, and so dark matter can still have an influence on the shape and motions of galaxies. But we'll never see it. At least, not directly.

As much as we would prefer to live in a simpler universe, dark matter is not the product of some astronomer's fever dream after a late-night observing session. It's only after decades of careful observations that cosmologists have come to the inescapable conclusion that most of the matter in our universe is simply invisible. [Dark Matter and Dark Energy: The Mystery Explained (Infographic)]

Too hot

The initial hints of dark matter came in the 1930s as astronomer Fritz Zwicky made the first X-ray observations of the Coma Cluster, a dense knot of a thousand galaxies over 300 million light-years away. The galaxies themselves aren't very bright in X-ray light, but the galaxies in a cluster swim in a hot, thin soup of plasma (a gas with some unique properties), which does emit high-energy radiation. In his initial measurements, Zwicky noticed an inconsistency: The plasma was much too hot.

Stable systems like galaxy clusters are a study in balance. In this case, the tendency of a hot gas to expand is balanced by the inward pull of its own gravity. If clusters are to survive for billions of years — which they must, in order for us to actually observe them all over the universe — then these two forces must be in equilibrium. But when Zwicky added up the masses of all the galaxies and the plasma itself, it was far too small; the inward gravitational pull of all that matter wasn't enough to overcome the natural expansion of the gas. In other words, the cluster should've — well, I don't want to say exploded, but you get the idea, long ago.

He named the missing mass "dunkle materie" ("dark matter" in German) and went on to figure out other problems.

Too fast

The concept of dark matter was largely ignored until the 1970s, when astronomer Vera Rubin made her groundbreaking measurements of the rotation speeds of stars within galaxies. Here, again, was a mystery: The stars appear to be orbiting far too fast. The galaxies should've flung themselves apart like a broken-down carnival ride long ago. Instead, there they were, stable as could be.

At this point, a dilemma emerged. Maybe there's some invisible matter floating around inside galaxies and clusters, keeping them gravitationally glued together. But maybe our understanding of how gravity works is just wrong; perhaps Newton's work can explain the way planets move in our solar system but not larger systems.

Without further evidence, two competing hypotheses, dark matter versus modified

Newtonian dynamics (which attempts to explain the mysteries mentioned above by adjusting the details of Newton's work), were on equal scientific footing. We simply couldn't tell them apart.

Too bumpy

That is, until more evidence came in. The first strong hints of a dark universe came from observations of the cosmic microwave background, the ancient afterglow light pattern from the hot and sweaty early years of the universe. That light is uniform to 1 part in 10,000, but buried in that all-surrounding glow are tiny variations, bumps and wiggles that give us a map of the universe at that age.

Those bumps and wiggles are also a study in balance, as multiple competing forces vied for dominance in the hot, dense plasma of the young cosmos. The outward pressure of radiation was resisted by the inward pull of matter's gravity, and that struggle was captured in a snapshot when the CMB was formed. By observing the patterns in the CMB, we can play a straightforward guess-the-recipe game: put various ingredients (normal matter, dark matter, radiation, modified gravity, etc.) into a pot, see what comes out, and compare directly to observations.

And try as we could, we just couldn't make those modified Newtonian dynamics and altered forces of gravity work. But an invisible component to the universe, one that didn't interact with radiation all? It seemed to fit the bill.

Too wide

Still, as is usual in science, there was room for debate. Perhaps not all the observations could be explained by the presence of dark matter, scientists thought. Maybe general relativity — still the most advanced theory we have on the nature of gravity — was not the be-all-end-all gravitational theory.

Those hopes were largely dashed in the most violent way possible — with a bullet. The Bullet Cluster, that is. Two massive galaxy clusters, each weighing in at hundreds of quadrillions of solar masses, slammed into each other long ago. One of the most energetic events in all of nature, the collision turned the clusters inside out, giving us a clue to their contents.

Different observations reveal different components of the Bullet Cluster. Visible light pinpoints the locations of the member galaxies, and they did about what you would expect after the collision: nothing much. The galaxies are so small compared to the volume of the cluster, they simply flew past each other like a swarm of bees.

X-rays expose the fate of the hot plasma between the galaxies. The gas got all tangled up at the midpoint of the collision, with all the complicated bow shocks, cold fronts and turbulence one would expect. This was space weather played out on the grandest of scales.

Also helpful was gravitational lensing, which allows scientists to map the location of matter (whether it interacts directly with radiation or not) based on the way its gravity bends the path of background light. The lensing maps for the Bullet Cluster show an intriguing pattern: most of the stuff in the Bullet Cluster is not tangled up in the center with the hot plasma, and it's not exactly associated with the galaxies, either.

Whatever material the majority of the Bullet Cluster is made of, it doesn't interact with light (otherwise we would see it) and it doesn't interact with itself (otherwise it would've gotten all twisted up during the interaction).

No. 1 with a Bullet

The Bullet Cluster, and a myriad of observations of similar objects, tie together our picture of dark matter along with other lines of evidence like stellar velocities in galaxies, the cosmic microwave background, and more. Nature is trying to tell us something, and we're doing our best to listen: The inescapable conclusion from multiple independent lines of evidence is that most of the matter in our universe is a new kind of particle; one that doesn't interact with light or even itself. It's dark matter.

We still haven't pinned down the exact character of the dark matter particle, but we are closing in on its properties. Sooner or later, nature will reveal to us even its darkest secrets.

Learn more by listening to the episode "What's the matter with dark matter?" on the Ask A Spaceman podcast, available on iTunes and on the Web at http://www.askaspaceman.com. Thanks to @kdawelch, Andreas C., Oscar Z., Peter W., William G., Olivia P., Matthew A, and @TheM4YOR. for the questions that led to this piece! Ask your own question on Twitter using #AskASpaceman or by following Paul @PaulMattSutter and facebook.com/PaulMattSutter.

Follow Calla Cofield @callacofield. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

Satellites Spy 2017 Solar Eclipse from Space (Videos)

Satellites Spy 2017 Solar Eclipse from Space (Videos):

The European Space Agency's Proba-2 satellite captured a partial solar eclipse three times on Aug. 21, 2017

Credit: ESA

While a long, narrow swath of the United States was treated to a total solar eclipse on Monday (Aug. 21), several different spacecraft captured views of a partially blocked sun.

NASA's Solar Dynamics Observatory (SDO) satellite recorded imagery in multiple wavelengths of light, as the following video shows:

The European Space Agency's Proba-2 satellite, which orbits Earth 14.5 times every day, observed a partial eclipse three times on Aug. 21 (just as astronauts aboard the International Space Station did), gaining several different perspectives of the event:

And the Hinode satellite — a joint mission of the Japan Aerospace Exploration Agency, NASA and other partners — captured imagery of the eclipse as well, which you can see looped here:

Monday's eclipse was the most anticipated skywatching event in decades. The 70-mile-wide (113 kilometers) "path of totality" ran through 14 states, from Oregon to South Carolina, marking the first time since 1918 that a total solar eclipse had gone coast to coast across the entire U.S. mainland. And no total solar eclipse had been visible from any part of the contiguous 48 states since 1979.

Weather permitting, everyone in North America outside the path of totality saw a partial solar eclipse Monday, as did observers in Central America, the Caribbean, northern South America, and parts of western Africa and Europe.

And everyone with an Internet connection had the chance to see totality, thanks to a variety of live webcasts. Many people tuned in; Monday's eclipse shattered NASA's web-traffic record, agency officials said.

Note: Space.com senior producer Steve Spaleta contributed to this report.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.

CASIS Awards Audacy Grant to Test Radio on Space Station

CASIS Awards Audacy Grant to Test Radio on Space Station:

Audacy's constellation is designed to provide high-availability mission critical communications to users anywhere in near Earth space.

Credit: Audacy

The nonprofit Center for the Advancement of Science in Space (CASIS) awarded a grant Aug. 17 to Audacy that will enable the Silicon Valley startup to demonstrate its high data-rate radio on the International Space Station.

Audacy, a company established in 2015 to create a commercial space-based communications network, plans to send the Audacy Lynq demonstration mission to the space station's NanoRacks External Payload Platform on a NASA commercial cargo fight in late 2018.

"We plan to demonstrate the efficacy of Audacy's high-rate customer terminal, as well as the utility of Audacy's communications services for downloading science and imagery data from customers onboard the ISS," Ellaine Talle, Audacy project lead, said by email.

On Aug. 8, Audacy announced a related project. The firm is working with Scotland's Clyde Space to send a cubesat into orbit in 2018 to demonstrate the performance of terminals customers flying small satellites can use to transmit data to Audacy's ground stations.

Talle declined to say the value of the CASIS award but said it was large enough to cover the cost of launching Audacy Lynq on a commercial cargo flight and a six-month test of Audacy K-band antenna and radio on the space station.

In 2019, Audacy plans to launch three large satellites into medium Earth orbit to relay data from spacecraft in low Earth orbit to ground stations. Audacy is establishing a global network of ground stations to communicate with its future relay satellites and to support customers operating missions beyond the relay satellites' field of view, Talle said.

"While we hope future ISS demonstrations will utilize the relays, this initial mission will only exercise the ground segment," she added.

This story was provided by SpaceNews, dedicated to covering all aspects of the space industry.

How did Hurricane Harvey get so strong?

How did Hurricane Harvey get so strong?:

Hurricane Harvey is whirling towards Texas with winds reaching 130 miles per hour — a Category 4 hurricane that was fueled by an unlucky pit stop over a deep patch of warm water in the Gulf of Mexico.

Warm water feeds hurricanes, which form when a weather disturbance, like a small storm, sucks the moist, warm air over the ocean’s surface into the lower atmosphere. When that moisture-laden air reaches cooler temperatures higher up in the atmosphere, the water condenses to form clouds — which spin and grow, fueled by more warm ocean water as it evaporates.

NEW: NOAA's #GOES16 shows a "sandwich loop" -- a combination of visible and infrared imagery -- of #HurricaneHarvey today, August 25, 2017. pic.twitter.com/o4EBfF69xZ

— NOAA...

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An ancient clay tablet shows that Babylonian scholars might have invented trigonometry

An ancient clay tablet shows that Babylonian scholars might have invented trigonometry:

A new interpretation into the nature of an ancient clay tablet known as Plimpton 322 claims that ancient Babylonians might have developed an advanced form of trigonometry — long before Greek mathematicians are commonly believed to have invented the concept.

That’s the theory put forward by two mathematicians from the University of New South Wales, Daniel F. Mansfield and Norman Wildberger, who published their study in the latest issue of Historia Mathematica. They claim that the tablet demonstrates a sophisticated understanding of mathematics, and that modern assumptions of the field should be reexamined in light of the interpretation.

The tablet in question is approximately five inches wide by three inch tall, and dates back to...

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Supermassive Black Holes Feed on Cosmic Jellyfish

Supermassive Black Holes Feed on Cosmic Jellyfish:

Observations of “Jellyfish galaxies” with ESO’s Very Large Telescope have revealed a previously unknown way to fuel supermassive black holes. It seems the mechanism that produces the tentacles of gas and newborn stars that give these galaxies their nickname also makes it possible for the gas to reach the central regions of the galaxies, feeding the black hole that lurks in each of them and causing it to shine brilliantly. The results appeared today in the journal Nature.

An Italian-led team of astronomers used the MUSE (Multi-Unit Spectroscopic Explorer) instrument on the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile to study how gas can be stripped from galaxies. They focused on extreme examples of jellyfish galaxies in nearby galaxy clusters, named after the remarkable long “tentacles” of material that extend for tens of thousands of light-years beyond their galactic discs.

The tentacles of jellyfish galaxies are produced in galaxy clusters by a process called ram pressure stripping. Their mutual gravitational attraction causes galaxies to fall at high speed into galaxy clusters, where they encounter a hot, dense gas which acts like a powerful wind, forcing tails of gas out of the galaxy’s disc and triggering starbursts within it.

Six out of the seven jellyfish galaxies in the study were found to host a supermassive black hole at the center, feeding on the surrounding gas. This fraction is unexpectedly high — among galaxies in general the fraction is less than one in ten.

“This strong link between ram pressure stripping and active black holes was not predicted and has never been reported before,” said team leader Bianca Poggianti from the INAF-Astronomical Observatory of Padova in Italy. “It seems that the central black hole is being fed because some of the gas, rather than being removed, reaches the galaxy center.”

A long-standing question is why only a small fraction of supermassive black holes at the centers of galaxies are active. Supermassive black holes are present in almost all galaxies, so why are only a few accreting matter and shining brightly? These results reveal a previously unknown mechanism by which the black holes can be fed.

Yara Jaffé, an ESO fellow who contributed to the paper explains the significance: “These MUSE observations suggest a novel mechanism for gas to be funneled towards the black hole’s neighborhood. This result is important because it provides a new piece in the puzzle of the poorly understood connections between supermassive black holes and their host galaxies.”

The current observations are part of a much more extensive study of many more jellyfish galaxies that is currently in progress.

“This survey, when completed, will reveal how many, and which, gas-rich galaxies entering clusters go through a period of increased activity at their cores,” concludes Poggianti. “A long-standing puzzle in astronomy has been to understand how galaxies form and change in our expanding and evolving Universe. Jellyfish galaxies are a key to understanding galaxy evolution as they are galaxies caught in the middle of a dramatic transformation.”

Credit: ESO

Scientists Improve Brown Dwarf Weather Forecasts

Scientists Improve Brown Dwarf Weather Forecasts:

Dim objects called brown dwarfs, less massive than the Sun but more massive than Jupiter, have powerful winds and clouds -- specifically, hot patchy clouds made of iron droplets and silicate dust. Scientists recently realized these giant clouds can move and thicken or thin surprisingly rapidly, in less than an Earth day, but did not understand why.

Now, researchers have a new model for explaining how clouds move and change shape in brown dwarfs, using insights from NASA's Spitzer Space Telescope. Giant waves cause large-scale movement of particles in brown dwarfs' atmospheres, changing the thickness of the silicate clouds, researchers report in the journal Science. The study also suggests these clouds are organized in bands confined to different latitudes, traveling with different speeds in different bands.

"This is the first time we have seen atmospheric bands and waves in brown dwarfs," said lead author Daniel Apai, associate professor of astronomy and planetary sciences at the University of Arizona in Tucson.

Just as in Earth's ocean, different types of waves can form in planetary atmospheres. For example, in Earth's atmosphere, very long waves mix cold air from the polar regions to mid-latitudes, which often lead clouds to form or dissipate.

The distribution and motions of the clouds on brown dwarfs in this study are more similar to those seen on Jupiter, Saturn, Uranus and Neptune. Neptune has cloud structures that follow banded paths too, but its clouds are made of ice. Observations of Neptune from NASA's Kepler spacecraft, operating in its K2 mission, were important in this comparison between the planet and brown dwarfs.

"The atmospheric winds of brown dwarfs seem to be more like Jupiter's familiar regular pattern of belts and zones than the chaotic atmospheric boiling seen on the Sun and many other stars," said study co-author Mark Marley at NASA's Ames Research Center in California's Silicon Valley.

Brown dwarfs can be thought of as failed stars because they are too small to fuse chemical elements in their cores. They can also be thought of as "super planets" because they are more massive than Jupiter, yet have roughly the same diameter. Like gas giant planets, brown dwarfs are mostly made of hydrogen and helium, but they are often found apart from any planetary systems. In a 2014 study using Spitzer, scientists found that brown dwarfs commonly have atmospheric storms.

Due to their similarity to giant exoplanets, brown dwarfs are windows into planetary systems beyond our own. It is easier to study brown dwarfs than planets because they often do not have a bright host star that obscures them.

"It is likely the banded structure and large atmospheric waves we found in brown dwarfs will also be common in giant exoplanets," Apai said.

Using Spitzer, scientists monitored brightness changes in six brown dwarfs over more than a year, observing each of them rotate 32 times. As a brown dwarf rotates, its clouds move in and out of the hemisphere seen by the telescope, causing changes in the brightness of the brown dwarf. Scientists then analyzed these brightness variations to explore how silicate clouds are distributed in the brown dwarfs.

Researchers had been expecting these brown dwarfs to have elliptical storms resembling Jupiter's Great Red Spot, caused by high-pressure zones. The Great Red Spot has been present in Jupiter for hundreds of years and changes very slowly: Such "spots" could not explain the rapid changes in brightness that scientists saw while observing these brown dwarfs. The brightness levels of the brown dwarfs varied markedly just over the course of an Earth day.

To make sense of the ups and downs of brightness, scientists had to rethink their assumptions about what was going on in the brown dwarf atmospheres. The best model to explain the variations involves large waves, propagating through the atmosphere with different periods. These waves would make the cloud structures rotate with different speeds in different bands.

University of Arizona researcher Theodora Karalidi used a supercomputer and a new computer algorithm to create maps of how clouds travel on these brown dwarfs.

"When the peaks of the two waves are offset, over the course of the day there are two points of maximum brightness," Karalidi said. "When the waves are in sync, you get one large peak, making the brown dwarf twice as bright as with a single wave."

The results explain the puzzling behavior and brightness changes that researchers previously saw. The next step is to try to better understand what causes the waves that drive cloud behavior.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

Credit: spitzer.caltech.edu

Astrophysicists Predict Earth-Like Planet in Star System Only 16 Light Years Away

Astrophysicists Predict Earth-Like Planet in Star System Only 16 Light Years Away:

Astrophysicists at the University of Texas at Arlington have predicted that an Earth-like planet may be lurking in a star system just 16 light years away. The team investigated the star system Gliese 832 for additional exoplanets residing between the two currently known alien worlds in this system. Their computations revealed that an additional Earth-like planet with a dynamically stable configuration may be residing at a distance ranging from 0.25 to 2.0 astronomical unit (AU) from the star.

“According to our calculations, this hypothetical alien world would probably have a mass between 1 to 15 Earth's masses,” said the lead author Suman Satyal, UTA physics researcher, lecturer and laboratory supervisor. The paper is co-authored by John Griffith, UTA undergraduate student and long-time UTA physics professor Zdzislaw Musielak.

The astrophysicists published their findings this week as “Dynamics of a probable Earth-Like Planet in the GJ 832 System” in The Astrophysical Journal.

UTA Physics Chair Alexander Weiss congratulated the researchers on their work, which underscores the University’s commitment to data-driven discovery within its Strategic Plan 2020: Bold Solutions | Global Impact.

“This is an important breakthrough demonstrating the possible existence of a potential new planet orbiting a star close to our own,” Weiss said. “The fact that Dr. Satyal was able to demonstrate that the planet could maintain a stable orbit in the habitable zone of a red dwarf for more than 1 billion years is extremely impressive and demonstrates the world class capabilities of our department’s astrophysics group.”

Gliese 832 is a red dwarf and has just under half the mass and radius of our sun. The star is orbited by a giant Jupiter-like exoplanet designated Gliese 832b and by a super-Earth planet Gliese 832c. The gas giant with 0.64 Jupiter masses is orbiting the star at a distance of 3.53 AU, while the other planet is potentially a rocky world, around five times more massive than the Earth, residing very close its host star—about 0.16 AU.

For this research, the team analyzed the simulated data with an injected Earth-mass planet on this nearby planetary system hoping to find a stable orbital configuration for the planet that may be located in a vast space between the two known planets.

Gliese 832b and Gliese 832c were discovered by the radial velocity technique, which detects variations in the velocity of the central star, due to the changing direction of the gravitational pull from an unseen exoplanet as it orbits the star. By regularly looking at the spectrum of a star – and so, measuring its velocity – one can see if it moves periodically due to the influence of a companion.

"We also used the integrated data from the time evolution of orbital parameters to generate the synthetic radial velocity curves of the known and the Earth-like planets in the system,” said Satyal, who earned his Ph.D. in Astrophysics from UTA in 2014. "We obtained several radial velocity curves for varying masses and distances indicating a possible new middle planet," the astrophysicist noted.

For instance, if the new planet is located around 1 AU from the star, it has an upper mass limit of 10 Earth masses and a generated radial velocity signal of 1.4 meters per second. A planet with about the mass of the Earth at the same location would have radial velocity signal of only 0.14 m/s, thus much smaller and hard to detect with the current technology.

“The existence of this possible planet is supported by long-term orbital stability of the system, orbital dynamics and the synthetic radial velocity signal analysis”, Satyal said. “At the same time, a significantly large number of radial velocity observations, transit method studies, as well as direct imaging are still needed to confirm the presence of possible new planets in the Gliese 832 system.”

In 2014, Noyola, Satyal and Musielak published findings related to radio emissions indicating that an exomoon could be orbiting an exoplanet in The Astrophysical Journal, where they suggested that interactions between Jupiter’s magnetic field and its moon Io may be used to detect exomoons at distant exoplanetary systems.

Zdzislaw Musielak joined the UTA physics faculty in 1998 following his doctoral program at the University of Gdansk in Poland and appointments at the University of Heidelberg in Germany; Massachusetts Institute of Technology, NASA Marshall Space Flight Center and the University of Alabama in Huntsville.

Suman Satyal is a research assistant, laboratory supervisor and physics lecturer at UTA and his research area includes the detection of exoplanets and exomoons, and orbital stability analysis of Exoplanets in single and binary star systems. He previously worked in the National Synchrotron Light Source located at the Brookhaven National Laboratory in New York, where he measured the background in auger-photoemission coincidence spectra associated with multi-electron valence band photoemission processes.

Credit: uta.edu

Astrophysicists Explain the Mysterious Behavior of Cosmic Rays

Astrophysicists Explain the Mysterious Behavior of Cosmic Rays:

A team of scientists from Russia and China has developed a model which explains the nature of high-energy cosmic rays (CRs) in our Galaxy. These CRs have energies exceeding those produced by supernova explosions by one or two orders of magnitude. The model focuses mainly on the recent discovery of giant structures called Fermi bubbles. The paper was published in EPJ Web of Conferences.

One of the key problems in the theory of the origin of cosmic rays (high-energy protons and atomic nuclei) is their acceleration mechanism. The issue was addressed by Vitaly Ginzburg and Sergei Syrovatsky in the 1960s when they suggested that CRs are generated during supernova (SN) explosions in the Galaxy. A specific mechanism of charged particle acceleration by SN shock waves was proposed by Germogen Krymsky and others in 1977. Due to the limited lifetime of the shocks, it is estimated that the maximum energy of the accelerated particles cannot exceed 0.1-1.0 PeV.

The question arises of how to explain the nature of particles with energies above 1 PeV. A major breakthrough in researching the acceleration processes of such particles came when the Fermi Gamma-ray Space Telescope detected two gigantic structures emitting radiation in gamma-ray band in the central area of the Galaxy in November 2010. The discovered structures are elongated and are symmetrically located in the Galactic plane perpendicular to its center, extending 50,000 light-years, or roughly half of the diameter of the Milky Way disk. These structures became known as Fermi bubbles. Later, the Planck telescope team discovered their emission in the microwave band.

The nature of Fermi bubbles is still unclear, however the location of these objects indicates their connection to past or present activity in the center of the galaxy, where a central black hole of 106 solar masses is believed to be located. Modern models relate the bubbles to star formation and/or an energy release in the Galactic center as a result of tidal disruption of stars during their accretion onto a central black hole. The bubbles are not considered to be unique phenomena observed only in the Milky Way and similar structures can be detected in other galactic systems with active nuclei.

Dmitry Chernyshov (MIPT graduate), Vladimir Dogiel (MIPT staff member) and their colleagues from Hong Kong and Taiwan have published a series of papers on the nature of Fermi bubbles. They have shown that X-ray and gamma-ray emission in these areas is due to various processes involving relativistic electrons accelerated by shock waves resulting from stellar matter falling into a black hole. In this case, the shock waves should accelerate both protons and nuclei. However, in contrast to electrons, relativistic protons with bigger masses hardly lose their energy in the Galactic halo and can fill up the entire volume of the galaxy. The authors of the paper suggest that giant Fermi bubbles shock fronts can re-accelerate protons emitted by SN to energies greatly exceeding 1 PeV.

Analysis of cosmic ray re-acceleration showed that Fermi bubbles may be responsible for the formation of the CR spectrum above the “knee” of the observed spectrum, i.e., at energies greater than 3 PeV. To put this into perspective, the energy of accelerated particles in the Large Hadron Collider is also about 1 PeV.

"The proposed model explains the spectral distribution of the observed CR flux. It can be said that the processes we described are capable of re-accelerating galactic cosmic rays generated in supernova explosions. Unlike electrons, protons have a significantly greater lifetime, so when accelerated in Fermi bubbles, they can fill up the volume of the Galaxy and be observed near the Earth. Our model suggests that the cosmic rays containing high-energy protons and nuclei with energy lower than 1 PeV (below the energy range of the observed spectrum’s "knee"), were generated in supernova explosions in the Galactic disk. Such CRs are re-accelerated in Fermi bubbles to energies over 1 PeV (above the "knee"). The final cosmic ray distribution is shown on the spectral diagram," says Vladimir Dogiel.

The researchers have proposed an explanation for the peculiarities in the CR spectrum in the energy range from 3 PeV to 1 EeV. The scientists have proven that particles produced during the SN explosions and which have energies lower than 3 PeV experience re-acceleration in Fermi bubbles when they move from the galactic disk to the halo. Reasonable parameters of the model describing the particles’ acceleration in Fermi bubbles can explain the nature of the spectrum of cosmic rays above 3 PeV. The spectrum below this range remains undisturbed. Thus, the model is able to produce spectral distribution of cosmic rays that is identical to the one observed.

Credit: mipt.ru

Astrophysicist Predicts Detached Eclipsing White Dwarfs to Merge Into an Exotic Star

Astrophysicist Predicts Detached Eclipsing White Dwarfs to Merge Into an Exotic Star:

A University of Oklahoma astrophysicist, Mukremin Kilic, and his team have discovered two detached, eclipsing double white dwarf binaries with orbital periods of 40 and 46 minutes, respectively. White dwarfs are the remnants of Sun-like stars, many of which are found in pairs, or binaries. However, only a handful of white dwarf binaries are known with orbital periods less than one hour in the Milky Way—a galaxy made up of two hundred billion stars—and most have been discovered by Kilic and his colleagues.

“Short-period white dwarf binaries are interesting because they generate gravitational waves. One of the new discoveries emits so much gravitational waves that it is a new verification source for the upcoming Laser Interferometer Space Antenna—a gravitational wave satellite,” Kilic said.

Kilic, an astrophysics professor in the Homer L. Dodge Department of Physics and Astronomy, with OU graduate students Alekzander Kosakowski and A. Gianninas, and collaborator Warren R. Brown, Smithsonian Astrophysical Observatory, discovered the two white dwarf binaries using the MMT 6.5-meter telescope, a joint facility of the Smithsonian Institution and the University of Arizona. Observations at the Apache Point Observatory 3.5-meter telescope revealed that one of the binaries is eclipsing, only the seventh known eclipsing white dwarf binary.

In the future, Kilic and his team will watch in real time as the stars eclipse to measure how they are getting closer and closer—a sign they will likely merge. What occurs when the white dwarfs make contact continues to be a mystery at this point. One possibility is an explosion—a phenomenon known as a supernova. Kilic predicts these two stars will come together and create an “exotic star,” known as R Coronae Borealis. These stars are often identified for their spectacular declines in brightness at irregular intervals. There are only about 65 R Coronae Borealis stars known in our galaxy.

“The existence of double white dwarfs that merge in 20 to 35 million years is remarkable,” Brown said. “It implies that many more such systems must have formed and merged over the age of the Milky Way.”

Kilic’s paper, “Discovery of a Detached, Eclipsing 40 Min Period Double White Dwarf Binary and a Friend: Implications for He+CO White Dwarf Mergers,” is available at https://arxiv.org/abs/1708.05287 in The Astrophysical Journal. Support for this project was provided by the Smithsonian Institution, the National Science Foundation and the National Atmospheric and Space Administration.

Credit: ou.edu

Two Newly Discovered Asteroids to Whiz by Earth on Tuesday

Two Newly Discovered Asteroids to Whiz by Earth on Tuesday:

Two space rocks detected this week are slated to pass by our planet on Tuesday, Aug. 22. The newly found asteroids, designated 2017 PV25 and 2017 QT1, are expected to miss the Earth at a distance of 5.5 lunar distances (LD) and 2.6 LD respectively (or 2.1 and 1 million kilometers).

2017 PV25 is an Apollo-type asteroid discovered Aug. 15 by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) at the Mauna Loa Observatory (MLO), Hawaii. It is an astronomical survey system for detection of dangerous asteroids a few weeks to days before their close approaches to Earth.

According to astronomers, 2017 PV25 has an absolute magnitude of 24.7 and a diameter between 23 and 71 meters. This near-Earth object (NEO) has a semimajor axis of about 1.06 AU and it takes it approximately one year and one month to fully orbit the sun. The space rock will miss our planet at 16:16 UTC with a relative velocity of 6.46 km/s.

2017 QT1 is also an Apollo-type asteroid, first spotted on Aug. 17 using the Pan-STARRS 1 (PS1) telescope at the summit of Haleakala on the Hawaiian island of Maui. The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) is an astronomical survey consisting of astronomical cameras, telescopes and a computing facility, surveying the sky for moving objects on a continual basis.

2017 QT1 is expected to pass by our planet at 18:24 UTC with a relative velocity of 20.6 km/s. The asteroid has an absolute magnitude of 26.7 and a diameter between 8 and 27 meters. This NEO has a semimajor axis of about 2.55 AU and an orbital period of approximately four years.

On Aug. 20, there were 1,803 Potentially Hazardous Asteroids (PHAs) detected and none of them is on a collision course with our planet. PHAs are asteroids larger than 100 meters that can come closer to Earth than 19.5 LD.

Scientists Create ‘Diamond Rain’ That Forms in the Interior of Icy Giant Planets

Scientists Create ‘Diamond Rain’ That Forms in the Interior of Icy Giant Planets:

In an experiment designed to mimic the conditions deep inside the icy giant planets of our solar system, scientists were able to observe “diamond rain” for the first time as it formed in high-pressure conditions. Extremely high pressure squeezes hydrogen and carbon found in the interior of these planets to form solid diamonds that sink slowly down further into the interior.

The glittering precipitation has long been hypothesized to arise more than 5,000 miles below the surface of Uranus and Neptune, created from commonly found mixtures of just hydrogen and carbon. The interiors of these planets are similar—both contain solid cores surrounded by a dense slush of different ices. With the icy planets in our solar system, “ice” refers to hydrogen molecules connected to lighter elements, such as carbon, oxygen and/or nitrogen.

Researchers simulated the environment found inside these planets by creating shock waves in plastic with an intense optical laser at the Matter in Extreme Conditions (MEC) instrument at SLAC National Accelerator Laboratory’s X-ray free-electron laser, the Linac Coherent Light Source (LCLS). SLAC is one of 10 Department of Energy (DOE) Office of Science laboratories.

In the experiment, the scientists were able to see that nearly every carbon atom of the original plastic was incorporated into small diamond structures up to a few nanometers wide. On Uranus and Neptune, the study authors predict that diamonds would become much larger, maybe millions of carats in weight. Researchers also think it’s possible that over thousands of years, the diamonds slowly sink through the planets’ ice layers and assemble into a thick layer around the core.

The research published in Nature Astronomy on August 21.

“Previously, researchers could only assume that the diamonds had formed,” said Dominik Kraus, scientist at Helmholtz Zentrum Dresden-Rossendorf and lead author on the publication. “When I saw the results of this latest experiment, it was one of the best moments of my scientific career.”

Earlier experiments that attempted to recreate diamond rain in similar conditions were not able to capture measurements in real time, because we currently can create these extreme conditions under which tiny diamonds form only for very brief time in the laboratory. The high-energy optical lasers at MEC combined with LCLS’s X-ray pulses—which last just femtoseconds, or quadrillionths of a second—allowed the scientists to directly measure the chemical reaction.

Other prior experiments also saw hints of carbon forming graphite or diamond at lower pressures than the ones created in this experiment, but with other materials introduced and altering the reactions.

The results presented in this experiment is the first unambiguous observation of high-pressure diamond formation from mixtures and agrees with theoretical predictions about the conditions under which such precipitation can form and will provide scientists with better information to describe and classify other worlds.

In the experiment, plastic simulates compounds formed from methane—a molecule with just one carbon bound to four hydrogen atoms that causes the distinct blue cast of Neptune.

The team studied a plastic material, polystyrene, that is made from a mixture of hydrogen and carbon, key components of these planets’ overall chemical makeup. 

In the intermediate layers of icy giant planets, methane forms hydrocarbon (hydrogen and carbon) chains that were long hypothesized to respond to high pressure and temperature in deeper layers and form diamond rain.

The researchers used high-powered optical laser to create pairs of shock waves in the plastic with the correct combination of temperature and pressure. The first shock is smaller and slower and overtaken by the stronger second shock. When the shock waves overlap, that’s the moment the pressure peaks and when most of the diamonds form, Kraus said. 

During those moments, the team probed the reaction with pulses of X-rays from LCLS that last just 50 femtoseconds. This allowed them to see the small diamonds that form in fractions of a second with a technique called femtosecond X-ray diffraction. The X-ray snapshots provide information about the size of the diamonds and the details of the chemical reaction as it occurs.

“For this experiment, we had LCLS, the brightest X-ray source in the world,” said Siegfried Glenzer, professor of photon science at SLAC and a co-author of the paper. “You need these intense, fast pulses of X-rays to unambiguously see the structure of these diamonds, because they are only formed in the laboratory for such a very short time.”

When astronomers observe exoplanets outside our solar system, they are able to measure two primary traits—the mass, which is measured by the wobble of stars, and radius, observed from the shadow when the planet passes in front of a star. The relationship between the two is used to classify a planet and help determine whether it may be composed of heavier or lighter elements.

“With planets, the relationship between mass and radius can tell scientists quite a bit about the chemistry,” Kraus said. “And the chemistry that happens in the interior can provide additional information about some of the defining features of the planet.”

Information from studies like this one about how elements mix and clump together under pressure in the interior of a given planet can change the way scientists calculate the relationship between mass and radius, allowing scientists to better model and classify individual planets. The falling diamond rain also could be an additional source of energy, generating heat while sinking towards the core.

“We can’t go inside the planets and look at them, so these laboratory experiments complement satellite and telescope observations,” Kraus said.

The researchers also plan to apply the same methods to look at other processes that occur in the interiors of planets.

In addition to the insights they give into planetary science, nanodiamonds made on Earth could potentially be harvested for commercial purposes—uses that span medicine, scientific equipment and electronics. Currently, nanodiamonds are commercially produced from explosives; laser production may offer a cleaner and more easily controlled method.

Research that compresses matter, like this study, also helps scientists understand and improve fusion experiments where forms of hydrogen combine to form helium to generate vast amounts of energy. This is the process that fuels the sun and other stars but has yet to be realized in a controlled way for power plants on Earth.

In some fusion experiments, a fuel of two different forms of hydrogen is surrounded by a plastic layer that reaches conditions similar to the interior of planets during a short-lived compression stage. The LCLS experiment on plastic now suggests that chemistry may play an important role in this stage. 

“Simulations don’t really capture what we’re observing in this field,” Glenzer said. “Our study and others provide evidence that matter clumping in these types of high-pressure conditions is a force to be reckoned with.”

The research collaboration includes scientists from Helmholtz Zentrum Dresden-Rossendorf in Germany, University of California-Berkeley, Lawrence Livermore National Laboratory, Lawrence Berkeley National Laboratory, GSI Helmholtz Center for Heavy Ion Research in Germany, Osaka University in Japan, Technical University of Darmstadt in Germany, European XFEL, University of Michigan, University of Warwick in the United Kingdom and SLAC.

The research was supported by DOE’s Office of Science and the National Nuclear Security Administration. LCLS is a DOE Office of Science User Facility. 

Credit: slac.stanford.edu

Great American Solar Eclipse of 2017 Wows Skywatchers

Great American Solar Eclipse of 2017 Wows Skywatchers:

The “Great American Eclipse” has officially ended. The first glimpses of the first total solar eclipse to cross the United States from coast to coast in 99 years began in Oregon, with totality just after 1 p.m. ET. What started as a tiny crescent of the moon's shadow turned into a perfectly beautiful eclipse in city after city. It ended in South Carolina about 3 p.m. ET. A partial solar eclipse was visible until just after 4 p.m. in the Southeast.

NASA’s G-III aircraft picked up the stunning celestial event in Salem, Oregon, showing the black orb of the moon covering the blazing sun to create a glowing halo.

The awe-inspiring moment cast total blackness over the area.

It then stretched across 13 other states: Idaho, a sliver of Montana, Wyoming, Nebraska, Kansas, a tiny portion of Iowa, Missouri, Illinois, Kentucky, Tennessee, Georgia, North Carolina and South Carolina.

In most places, the total eclipse lasted less than one minute, but the longest period of darkness lasted 2 minutes and 44 seconds over Shawnee National Forest in southern Illinois.

Millions of people moved to get into the path of darkness, putting on their protective glasses to gaze at the sky in wonder.

It was the first total solar eclipse visible from America's lower 48 states in 38 years, and the first since 1918 to track from coast to coast.

In Washington, D.C., where the sun was about 80 percent obscured by the moon, President Trump, Melania Trump and their son, Barron Trump, took in the scene from the Blue Room Balcony just after 2:30 p.m. ET.

The president waved to the onlookers at the White House, and gave a thumbs-up gesture when a reporter inquired about the view. He observed the eclipse at its apex wearing glasses with Mrs. Trump for about 90 seconds.

The Atlantic coastal city of Charleston was the final big urban area tasked with saying goodbye to the eclipse. It experienced the full shadow at 2:47 p.m. ET.

Then totality headed out past Fort Sumter in Charleston Harbor, across the coastal wetlands and out into the Atlantic.

Although, the US had exclusive rights on totality, a partial eclipse was visible across all of North America and the north of South America.

Parts of western Europe were also set to see the moon take a little chunk out of the sun at the end of the day just before the star dipped below the horizon.

The next total solar eclipse on Earth is on July 2, 2019, over the South Pacific, Chile, Argentina.

Credit: cnn.com, nypost.com, nytimes.com, bbc.com