Astronomy

Seldom Bucket

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Mercury's 400 C heat may help it make its own ice

It is already hard to believe that there is ice on Mercury, where daytime temperatures reach 400 degrees Celsius, or 750 degrees Fahrenheit. Now an upcoming study says that the Vulcan heat on the planet closest to the sun likely helps make some of that ice.

As with Earth, asteroids delivered most of Mercury's water, the scientific consensus holds. But the extreme daytime heat could be combining with the minus 200-degree Celsius cold in nooks of polar craters that never see sunlight to act as a gigantic ice-making chemistry lab, say researchers at the Georgia Institute of Technology.

The chemistry is not too complicated. But the new study models it onto complex conditions on Mercury, including solar winds that pelt the planet with charged particles, many of which are protons key to that chemistry. The model presents a feasible path for water to arise and collect as ice on a planet rife with all the necessary components.

More At: https://phys.org/news/2020-03-mercury-ice.html
 

Seldom Bucket

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New Study Shows the Earth and Moon are not so Similar After All

According to the most widely-accepted theory, the Moon formed roughly 4.5 billion years ago when a Mars-sized object named Theia collided with Earth (aka. the Giant Impact Hypothesis). This impact threw up considerable amounts of debris which gradually coalesced to form Earth’s only natural satellite. One of the most compelling proofs for this theory is the fact that the Earth and the Moon are remarkably similar in terms of composition.

However, previous studies involving computer simulations have shown that if the Moon were created by a giant impact, it should have retained more material from the impactor itself. But according to a new study conducted by a team from the University of New Mexico, it is possible that the Earth and the Moon are not as similar as previously thought.

More At: https://www.universetoday.com/14541...-earth-and-moon-are-not-so-similar-after-all/
 

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What Is the Geometry of the Universe?

When you gaze out at the night sky, space seems to extend forever in all directions. That’s our mental model for the universe, but it’s not necessarily correct. There was a time, after all, when everyone thought the Earth was flat, because our planet’s curvature was too subtle to detect and a spherical Earth was unfathomable.

Today, we know the Earth is shaped like a sphere. But most of us give little thought to the shape of the universe. Just as the sphere offered an alternative to a flat Earth, other three-dimensional shapes offer alternatives to “ordinary” infinite space.
We can ask two separate but interrelated questions about the shape of the universe. One is about its geometry: the fine-grained local measurements of things like angles and areas. The other is about its topology: how these local pieces are stitched together into an overarching shape.

More At: https://www.quantamagazine.org/what-is-the-geometry-of-the-universe-20200316/
 

Seldom Bucket

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Axions Would Solve Another Major Problem in Physics

Physicists have long hypothesized the existence of a minuscule particle called the axion that could single-handedly solve two mysteries. It could account for a puzzling property of quarks, the elementary particles inside protons and neutrons, and it could comprise the dark matter that fills the cosmos. Now, the authors of a paper that will be published this week in Physical Review Letters show that the axion could be the rare stone that kills a third bird as well — the question of why there’s so much more matter than antimatter in the universe.

“We found some new dynamics of the axion which produce the matter-antimatter asymmetry,” said Keisuke Harigaya, a physicist at the Institute for Advanced Study in Princeton, New Jersey, who collaborated on the work with Raymond Co of the University of Michigan.

 

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There Are Infinite Rings of Light Around Black Holes. Here's How We Could See Them

A year ago, history was made. The long, painstaking work of scientists around the globe produced the very first direct image of the event horizon of a black hole, a supermassive monster called M87* 55 million light-years away. That glorious, golden, blurry image confirmed many of our ideas about black holes.


But the science didn't stop when the image came in. A team of scientists has now performed calculations based on what we learnt from M87* combined with the predictions of general relativity, to further predict how one day we could see this objects in much closer detail.

Black holes are incredibly gravitationally intense. Not only are they so massive that even light speed is too slow to achieve escape velocity against their gravitational pull, they also bend the path of passing light around them, beyond the event horizon.

 

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SpaceX plans first manned flight to space station in May

Elon Musk's SpaceX will send astronauts to the International Space Station for the first time in May, NASA said, announcing the first crewed launch from the United States to the platform since 2011.

The tech entrepreneur's company will launch a Falcon 9 rocket to transport NASA astronauts Bob Behnken and Doug Hurley in a first for the space agency as it looks to cut costs.

"NASA and SpaceX are currently targeting no earlier than mid-to-late May for launch," the US space agency said in a statement Wednesday.

In March, Musk's Crew Dragon capsule made a round trip to the ISS, which is in orbit more than 250 miles (400 kilometers) above Earth, with a mannequin on board, before returning to the Atlantic after six days in space.

 

biometrics

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If I want to get into astronomy photography, what would a decent but budget setup cost? Do you know?
 

biometrics

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Depends, self tracking telescope, camera mountings and do you already have a DSLR camera?
I've got nothing. From some of the Reddit posts I gather it needs to be self tracking as the exposures are hours at a time.
 

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Blazar Found Blazing When the Universe was Only a Billion Years Old

Since the 1950s, astronomers have known of galaxies that have particularly bright centers – aka. Active Galactic Nuclei (AGNs) or quasars. This luminosity is the result of supermassive black holes (SMBHs) at their centers consuming matter and releasing electromagnetic energy. Further studies revealed that there are some quasars that appear particularly bright because their relativistic jets are directed towards Earth.

In 1978, astronomer Edward Speigel coined the term “blazar” to describe this particular class of object. Using the telescopes at the Large Binocular Telescope Observatory (LBTO) in Arizona, a research team recently observed a blazar located 13 billion light-years from Earth. This object, designated PSO J030947.49+271757.31 (or PSO J0309+27), is the most distant blazar ever observed and foretells the existence of many more!

 

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Sudden Ancient Global Warming Event Traced to Magma Flood

Roughly 60 million years ago, circulation changes deep within our planet generated a hot current of rock — the Iceland plume — causing it to rise from the heart of Earth’s mantle. When the mantle rock pierced the bottom of the North Atlantic Ocean, lava spurted across Scotland, Ireland and Greenland, scabbing into spectacular columned landscapes like the Giant’s Causeway in Northern Ireland and Scotland’s Fingal’s Cave.

That opening salvo was followed 4 million years later by a second gigantic pulse of hot mantle rock, which once again rode up the Iceland plume. It swelled under the seafloor and lifted a wide region of ocean floor between Greenland and Europe into the air, forming a temporary land bridge connecting Scotland and Greenland.

 

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Elon Musk says that SpaceX Has no Plans to Spin Off Starlink

Last week, the Satellite 2020 Conference & Exhibition wrapped up after four days of presentations and addresses from some of the leading experts in the telecommunications industry. As advertised, SpaceX founder Elon Musk was on hand to deliver a keynote speech in which he announced that (contrary to earlier statements) Starlink will not be spun off and become its own business enterprise.


This comes a little over a month and a half after Gwynne Shotwell, the President and Chief Operations Officer (COO) of SpaceX, stated during a private investor event that the company was considering spinning Starlink off and making it a publicly-traded company. But as Musk stated at the conference in Washington, D.C., SpaceX is too busy “thinking about that zero” to take the company public right now.

This decision is likely inspired by previous telecommunication companies that attempted to deploy large satellite constellations only to go bankrupt – which include Iridium, Globalstar, Orbcomm and Teledesic. All of these companies, save Teledesic, managed to recover in time with the deployment of second-generation constellations.
 

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Astronomers have found the edge of the Milky Way at last

Our galaxy is a whole lot bigger than it looks. New work finds that the Milky Way stretches nearly 2 million light-years across, more than 15 times wider than its luminous spiral disk. The number could lead to a better estimate of how massive the galaxy is and how many other galaxies orbit it.
Astronomers have long known that the brightest part of the Milky Way, the pancake-shaped disk of stars that houses the sun, is some 120,000 light-years across (SN: 8/1/19). Beyond this stellar disk is a disk of gas. A vast halo of dark matter, presumably full of invisible particles, engulfs both disks and stretches far beyond them (SN: 10/25/16). But because the dark halo emits no light, its diameter is hard to measure.

Now, Alis Deason, an astrophysicist at Durham University in England, and her colleagues have used nearby galaxies to locate the Milky Way’s edge. The precise diameter is 1.9 million light-years, give or take 0.4 million light-years, the team reports February 21 in a paper posted at arXiv.org.
To put that size into perspective, imagine a map in which the distance between the sun and the Earth is just one inch. If the Milky Way’s heart were at the center of the Earth, the galaxy’s edge would be four times farther away than the moon actually is.
 

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A Rapid End Strikes the Dinosaur Extinction Debate

The last time the world was ending, two cataclysms aligned. On one side of the planet, a wayward asteroid dropped like a cartoon anvil, punching through the edge of the Yucatan Peninsula and penetrating deep into Earth’s crust. Around the same time — 66 million years ago — a million cubic kilometres of lava were in the process of bubbling up to the surface, releasing climate-altering carbon dioxide and sulphur into the atmosphere and forming what would become the Deccan Traps of modern-day India.

Rock layers around the world show what happened next. No dinosaurs besides the birds made it out. Neither did the squid like ammonites that curled like rams’ horns, or marine reptiles including the plesiosaurs (Loch Ness conspiracies notwithstanding). But because of the close timing of the asteroid and the volcanism, geologists have spent years staking out increasingly acrimonious positions on which one deserves the blame for the ensuing carnage. In 2018, The Atlantic called the debate “The Nastiest Feud in Science.”

 

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If Pluto has a subsurface ocean, it may be old and deep

A suspected subsurface ocean on Pluto might be old and deep.

New analyses of images from NASA’s New Horizons spacecraft suggest that the dwarf planet has had an underground ocean since shortly after Pluto formed 4.5 billion years ago, and that the ocean may surround and interact with the rocky core.

If so, oceans could be common at the solar system’s edge — and may even be able to support life. That possibly “transforms the way we think about the Kuiper Belt,” the region of icy objects beyond the orbit of Neptune (SN: 3/27/19), says planetary scientist Adeene Denton of Purdue University in West Lafayette, Ind.

On its pass through the Kuiper Belt in 2015, New Horizons revealed that despite the dwarf planet’s location nearly 6 billion kilometers from the sun, Pluto showed signs of hosting an ocean of liquid water beneath an icy shell (SN: 9/23/16).

How much liquid may lie beneath Pluto’s ground, how long it’s been there, and how much the water may have partially frozen over time is hard to tell from the surface. The new research, which had been scheduled for presentation the week of March 16 at the canceled Lunar and Planetary Science Conference in The Woodlands, Texas, has dug into those questions.

 

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This Galaxy is the Very Definition of “Flocculent”

I know you’re Googling “flocculent” right now, unless you happen to be a chemist, or maybe a home brewer.

You could spend each day of your life staring at a different galaxy, and you’d never even come remotely close to seeing even a tiny percentage of all the galaxies in the Universe. Of course, nobody knows for sure exactly how many galaxies there are. But there might be up to two trillion of them. If you live to be a hundred, that’s only 36,500 galaxies that you’d look at. Puts things in perspective.


But science and astronomy transcend the life-span of any single individual human. Astronomy is a species-wide endeavour. And to serve that endeavour, we keep developing better and better telescopes and technology. One of astronomy’s premier instruments is the Hubble Space Telescope, even after all these years of stalwart observing.

 

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This Galaxy Has Only One Spiral Arm

There are all kinds of odd things in the sky. Things that defy our naming conventions, and our attempts to understand them. For instance, NGC 4618, the one-armed galaxy.


A spiral galaxy with only one arm may not top the list of cosmic oddities, but it does capture the minds of curious astronomers. The obvious question is: why does it only have one arm? Well, nobody’s absolutely certain yet.

William Herschel discovered NGC 4618 in 1787, about 6 years after his most famous discovery, Uranus. He built powerful telescopes that allowed him to make these discoveries. Herschel made numerous other discoveries as well.


Herschel also theorized that the fuzzy clumps astronomers saw in the sky, and which were called nebulae in the Messier catalog, were actually groups of individual stars, but that they were too far away to be discerned. Now we know he was right, and every school-kid knows about galaxies, and that we live in one.

 

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Astronomers saw a star dancing around a black hole
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For the first time, astronomers have observed a star orbiting the supermassive black hole at the center of our Milky Way galaxy. And the star is dancing to the predicted tune of Albert Einstein's general theory of relativity. The study published Thursday in the journal Astronomy & Astrophysics.

Observations of the star were made by astronomers using the European Southern Observatory's Very Large Telescope in Chile's Atacama Desert. They saw that the star's orbit is shaped like a rosette. Isaac Newton's theory of gravity suggested the orbit would look like an ellipse, but it doesn't. The rosette shape, however, holds up Einstein's theory of relativity. For the first time, astronomers have observed a star orbiting the supermassive black hole at the center of our Milky Way galaxy. And the star is dancing to the predicted tune of Albert Einstein's general theory of relativity.

"Einstein's general relativity predicts that bound orbits of one object around another are not closed, as in Newtonian gravity, but precess forwards in the plane of motion," said Reinhard Genzel, in a statement. He is the director at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. Genzel also led a program that demonstrated this result. The initiative strove for increasing the precision of measurements over a 30-year period.

Special effects
"This famous effect -- first seen in the orbit of the planet Mercury around the Sun -- was the first evidence in favour of general relativity," Genzel said. "One hundred years later we have now detected the same effect in the motion of a star orbiting the compact radio source Sagittarius A* at the centre of the Milky Way. This observational breakthrough strengthens the evidence that Sagittarius A* must be a supermassive black hole of 4 million times the mass of the sun."

Sagittarius A* is the supermassive black hole at the center of our galaxy. It's 26,000 light-years from the sun. Our solar system exists on the edge of one of the Milky Way's massive spiral arms. Dense stars can be found around the black hole. One of them, the star known as S2 in this observation, passes closest to the black hole within less than 20 billion kilometers.

It's one of the closest stars to be found orbiting the black hole. And when it nears the black hole, the star is moving at 3% the speed of light. It takes 16 Earth years for the star to complete an orbit around the black hole. "After following the star in its orbit for over two and a half decades, our exquisite measurements robustly detect S2's Schwarzschild precession in its path around Sagittarius A*," said Stefan Gillessen, who led the analysis of the measurements at the Max Planck Institute for Extraterrestrial Physics.

Orbits aren't usually perfect circles. Instead, objects move closer in or further away during rotation. S2's closest approach of the black hole changes each time, which helps create the rosette shape. And the theory of general relativity predicts how much that orbit changes.

A clearer picture

The theory also allowed them to understand more about the general area at the center of our galaxy, which is difficult for us to see from such a distance since it's clouded by gas and dust in our galaxy. Observations of the star over the period of 27 years made this discovery possible. The same team also previously reported the way the star's light stretches as it approaches the black hole.

"Our previous result has shown that the light emitted from the star experiences general relativity. Now we have shown that the star itself senses the effects of general relativity," said Paulo Garcia, study co-author and a researcher at Portugal's Centre for Astrophysics and Gravitation. Future telescopes, like the European Southern Observatory's Extremely Large Telescope, will allow for observations of fainter stars that move even closer to the black hole. "If we are lucky, we might capture stars close enough that they actually feel the rotation, the spin, of the black hole," said Andreas Eckart, study co-author and project lead scientist from Cologne University in Germany. "That would be again a completely different level of testing relativity."

 

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Earth-size, habitable-zone planet found hidden in early NASA Kepler data

A team of transatlantic scientists, using reanalyzed data from NASA's Kepler space telescope, has discovered an Earth-size exoplanet orbiting in its star's habitable zone, the area around a star where a rocky planet could support liquid water.

Scientists discovered this planet, called Kepler-1649c, when looking through old observations from Kepler, which the agency retired in 2018. While previous searches with a computer algorithm misidentified it, researchers reviewing Kepler data took a second look at the signature and recognized it as a planet. Out of all the exoplanets found by Kepler, this distant world—located 300 light-years from Earth—is most similar to Earth in size and estimated temperature.


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