Showing posts with label Solar System. Show all posts
Showing posts with label Solar System. Show all posts
Wednesday, April 10, 2019
Scientists reveal first image ever made of a black hole
WASHINGTON (AP) — Scientists on Wednesday revealed the first image ever made of a black hole, depicting its hot, shadowy edges where light bends around itself in a cosmic funhouse effect.
Assembling data gathered by eight radio telescopes around the world, astronomers created the picture showing the violent neighborhood around a supermassive black hole, the light-sucking monsters of the universe theorized by Einstein more than a century ago and confirmed by observations for decades.
It looked like a flaming orange, yellow, and black ring.
“We have seen what we thought was unseeable. We have seen and taken a picture of a black hole. Here it is,” said Sheperd Doeleman of Harvard.
Jessica Dempsey, a co-discoverer and deputy director of the East Asian Observatory in Hawaii, said it reminded her of the powerful flaming Eye of Sauron from the “Lord of the Rings” trilogy.
Unlike smaller black holes that come from collapsed stars, supermassive black holes are mysterious in origin. Situated at the center of most galaxies, including ours, they are so dense that nothing, not even light, can escape their gravitational pull. This one’s “event horizon” — the point of no return around it, where light and matter begin to fall inexorably into the abyss — is as big as our entire solar system.
Three years ago, scientists using an extraordinarily sensitive observing system heard the sound of two much smaller black holes merging to create a gravitational wave, as Albert Einstein predicted. The new image, published in the Astrophysical Journal Letters and announced around the world in several news conferences, adds light to that sound.
Outside scientists suggested the achievement could be worthy of a Nobel Prize, just like the gravitational wave discovery.
While much around a black hole falls into a death spiral and is never to be seen again, the new image captures “lucky gas and dust” circling at just far enough to be safe and seen millions of years later on Earth, Dempsey said.
Taken over four days when astronomers had “to have the perfect weather all across the world and literally all the stars had to align,” the image helps confirm Einstein’s general relativity theory, Dempsey said. Einstein a century ago even predicted the symmetrical shape that scientists just found, she said.
“It’s circular, but on one side the light is brighter,” Dempsey said. That’s because that light is approaching Earth.
The measurements are taken at a wavelength the human eye cannot see, so the astronomers added color to the image. They chose “exquisite gold because this light is so hot,” Dempsey said. “Making it these warm gold and oranges makes sense.”
What the image shows is gas heated to millions of degrees by the friction of ever-stronger gravity, scientists said. And that gravity creates a funhouse effect where you see light from both behind the black hole and behind you as the light curves and circles around the black hole itself, said astronomer Avi Loeb, director of the Black Hole Initiative at Harvard. (The lead scientists in the discovery are from Harvard, but Loeb was not involved.)
The project cost $50 million to $60 million, with $26 million of that coming from the National Science Foundation.
Johns Hopkins astrophysicist Ethan Vishniac, who was not part of the discovery team but edits the journal where the research was published, pronounced the image “an amazing technical achievement” that “gives us a glimpse of gravity in its most extreme manifestation.”
He added: “Pictures from computer simulations can be very pretty, but there’s literally nothing like a picture of the real universe, however fuzzy and monochromatic.”
“It’s just seriously cool,” said John Kormendy, a University of Texas astronomer who wasn’t part of the discovery team. “To see the stuff going down the tubes, so to speak, to see it firsthand. The mystique of black holes in the community is very substantial. That mystique is going to be made more real.”
There is a myth that says a black hole would rip you apart, but Loeb and Kormendy said the one pictured is so big, someone could fall into it and not be torn to pieces. But the person would never be seen from again.
Black holes are “like the walls of a prison. Once you cross it, you will never be able to get out and you will never be able to communicate,” Loeb said.
The first image is of a black hole in a galaxy called M87 that is about 53 million light years from Earth. One light year is 5.9 trillion miles, or 9.5 trillion kilometers. This black hole is about 6 billion times the mass of our sun.
The telescope data was gathered by the Event Horizon Telescope two years ago, but it took so long to complete the image because it was a massive undertaking, involving about 200 scientists, supercomputers and hundreds of terabytes of data delivered worldwide by plane.
The team looked at two supermassive black holes, the M87 and the one at the center of our own Milky Way galaxy. The one in our galaxy is closer but much smaller, so they both look the same size in the sky. But the more distant one was easier to take pictures of because it rotates more slowly.
“We’ve been hunting this for a long time,” Dempsey said. “We’ve been getting closer and closer with better technology.” /kga
source: technology.inquirer.net
Saturday, November 15, 2014
Comet craft takes selfie amid landing fumble
BERLIN—A shadow was cast— literally—across Europe’s historic mission to land on and explore a comet. Scientists said on Thursday the landing craft not only bounced twice, it also came to rest next to a cliff that’s blocking sunlight from its solar panels.
The good news is that the lander Philae is stable and in good health: Its scientific instruments have already begun gathering reams of data to send back to Earth, including the first pictures taken from the surface of a comet.
The bad news is that its useful lifetime may now be much shorter.
With just a day or two left before the lander’s primary battery is exhausted, scientists were considering what acrobatic maneuvers to risk in order to get the solar panels out of the shadows so they can keep Philae going for a few more months.
First photos
The first photos sent back to Earth revealed the comet’s rocky terrain, including an image that showed one of the lander’s three feet in the corner of the frame. They indicate that Philae’s instruments are working properly, said Jean-Pierre Bibring, the lander’s lead scientist at the European Space Agency.
Before deciding whether to try to adjust the lander, scientists will spend the next day or two collecting as much data as possible while its primary battery still has energy.
The lander’s solar panels were designed to provide an extra hour of battery life each day after that, but this may not be possible now.
Cosmic first
“We see that we get less solar power than we planned for,” said Koen Geurts of the lander team.
“This, of course, has an impact on our … capabilities to conduct science for an extended period of time,” he said. “Unfortunately this is not a situation that we were hoping for.”
The lander scored a cosmic first on Wednesday, touching down on comet 67P/Churyumov-Gerasimenko after a decade-long, 6.4-billion-kilometer (4-billion-mile) journey through space aboard its mother ship, Rosetta.
The comet is streaking through space at 65,983 km (41,000 miles), some 500,505,984 km (311 million miles) from Earth.
Thrusters fail
The landing was beset by a series of problems that began when thrusters meant to push Philae onto the comet failed. Then two harpoons, which should have anchored the lander to the surface, weren’t deployed.
This caused the lander to bounce off the comet and drift through the void for two hours before touching down again.
After a second smaller bounce, scientists believe it came to rest in a shallow crater on the comet’s 4-km-wide body, or nucleus.
Cliff meters away
“We are just in the shadow of a cliff,” Bibring said, adding that photos indicate the cliff could be just a few meters away. “We are in a shadow permanently, and that is part of the problem.”
Bibring and his colleagues stressed that the data they’ll be able to collect with the primary batteries alone will have made the landing worthwhile.
“A lot of science is getting covered now,” he said, noting that soon scientists will get their hands on a tomography of the comet and data showing whether the matter it is made of is magnetized.
Drilling is dangerous
But because the lander is just resting on the comet with nothing but low gravity holding it down, Philae will have to hold off on one of the most important experiments—drilling into the comet to extract some of the material buried beneath the surface.
Scientists want to analyze this material because it has remained almost unchanged for 4.5 billion years, making it something of a cosmic time capsule.
“Drilling without being anchored and without knowing how you are on the surface is dangerous. We might just tip over the lander,” said Stephan Ulamec, head of operations for Philae.
Gravity on the comet is 1/100,000th that of Earth, meaning the washing-machine-sized lander weighs just 1 gram (0.04 ounces) there.
In hibernation
Ground controllers will likely wait until the first big batch of data has been collected before attempting to adjust the lander so that its solar panels can catch the sun and charge its batteries.
Communication with the lander is slow, with signals taking more than 28 minutes to travel between Earth and the Rosetta orbiter flying above the comet.
Even if Philae uses up all its energy, it will remain on the comet in a mode of hibernation for the coming months.
The comet is on a six-and-a-half-year elliptical orbit around the sun, and at the moment it is getting closer. So, in theory, Philae could wake up again if the comet passes the sun in such a way that the solar panels catch more light, Ulamec said.
$1.6-B project
Meanwhile, the Rosetta orbiter will also use its 11 instruments to analyze the comet over the coming months.
Scientists hope the $1.6-billion project will help them better understand comets and other celestial objects, as well as possibly answer questions about the origins of life on Earth. AP
source: technology.inquirer.net
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