Showing posts with label Science. Show all posts
Showing posts with label Science. Show all posts
Shkencëtarët njoftuan të enjten
zbulimin e tre planetëve që janë disa prej kandidatëve më të mirë deri
më tani për vende të banueshme, jashtë sistemit tonë diellor, dhe ata
janë në një distancë shumë të largët nga planeti tokë, shkruan “CNN”.
Sateliti Kepler i NASA-ës, që
është duke vëzhguar më shumë se 150.000 yje, me shpesën e gjetjes së një
vendi të banueshëm, kanë zbuluar të paktën tre plante ku mund të ketë
jetë. Dy nga planetet – Kepler-62e dhe Kepler-62f – janë publikuar në
një studim të enjten në revistën “Science”.
Këto janë planetet të vogla të
gjetura ndonjëherë në “zonën e banueshme”, zona pranë një yll në të
cilën teorikisht ka prezencë uji të lëngshëm.
Pavel Vinogradov, a cosmonaut for two decades, claimed the honor as he emerged from the hatch with Roman Romanenko. But he inadvertently added to the booming population of space junk when he lost his grip on an experiment tray that he was retrieving toward the end of the 6 1/2-hour spacewalk.
The lost aluminum panel -- 18 inches by 12 inches and about 6 1/2 pounds -- contained metal samples. Scientists wanted to see how the samples had fared after a year out in the vacuum of space.
Otherwise, the spacewalk had gone well, with the spacewalkers installing new science equipment and replacing a navigation device needed for the June arrival of a European cargo ship.
Collecting the experiment tray was Vinogradov's last task outside.
The tray drifted toward the solar panels of the main Russian space station compartment, called Zvezda, Russian for Star. Flight controllers did not believe it struck anything, and the object was not thought to pose a safety hazard in the hours and days ahead.
"That's unfortunate," someone radioed in Russian.
Another panel of similar experiments will be collected on a future spacewalk.
This is the first of eight spacewalks to be conducted this year, most of them by Russians. Two will be led by NASA this summer.
Until Friday, the oldest spacewalker was retired NASA astronaut Story Musgrave, who was 58 when he helped fix the Hubble Space Telescope in 1993.
Romanenko, 41, is a second-generation spaceman who's following in his father's bootsteps. Retired cosmonaut Yuri Romanenko performed spacewalks back in the 1970s and 1980s. This is the son's first experience out in the vacuum of space.
Vinogradov made his seventh spacewalk; he ventured into a dark, ruptured chamber at Russia's old Mir space station in 1997 following a cargo ship collision. He arrived late last month for a six-month stay at the space station; he'll turn 60 aboard the orbiting complex in August.
The spacewalkers joked as they toiled 260 miles above the planet.
"I'm afraid of the darkness," one of them said in Russian as the space station passed over the night side of Earth.
Russian flight controllers outside Moscow oversaw Friday's action. The four other space station residents monitored the activity from inside; Canadian commander Chris Hadfield drew the short straw and had to work on a balky toilet.
“It’s just the tip of the iceberg,” says Sara Seager, an astronomer at MIT who was not part of the study. “When one type of object is found, there are many more just under the surface waiting to be discovered.”
Kepler’s latest discovery is a five-planet system around a star called Kepler-62, some 1,200 light-years away in the constellation Lyra. Astronomers found the planets by analyzing nearly three years’ worth of data. The inner three worlds are too hot for life, but planets Kepler-62e and Kepler-62f are far more accommodating. They are 1.6 and 1.4 times the diameter of Earth, respectively, and their orbits are within the boundaries of the habitable zone in which scientists think liquid water could exist.
“They are great candidates for being habitable planets,” says William Borucki, Kepler’s principal investigator, who came up with the idea for the planet-hunting telescope in the 1970s.
Kepler-62f is particularly intriguing, says Rory Barnes, an astronomer at the University of Washington, Seattle who was not involved in the research. It receives less energy from its star than Earth does from the sun, but if it has a relatively thick, heat-trapping atmosphere, it could sustain a comfortable surface temperature. “It’s not inconceivable to think about walking on the surface of 62f,” Borucki says.
Kepler-62e is less of a sure thing, Barnes says. It may be too close to its star – and therefore too hot – to sustain life. And if 62e is a rocky planet, it’s almost certainly tidally locked with its star, with one half of its surface always illuminated and the other perpetually dark.
But analyses from the Planetary Habitability Laboratory at the University of Puerto Rico, which evaluates the chances for life on every discovered exoplanet, disagree. The lab ranks 62e as the most Earthlike world ever found.
The biggest uncertainty about both planets is their composition. Kepler detects planets by looking for their shadows as they cross in front of their stars. Just as a golf ball and a ping-pong ball cast similar shadows, a rocky planet crossing in front of its star is indistinguishable from one composed entirely of gas or water with no solid surface.
Kepler began snagging sizzling giant planets in May 2009, almost as soon as it started staring at 170,000 stars for signs of orbiting planets. Lately the mission’s discoveries have become considerably more Earthlike. Researchers announced the discovery of the first Earth-sized worlds in December 2011, along with the first Kepler planet to orbit in its star’s habitable zone. That planet, Kepler-22b, is so large that it probably resembles a hot, miniature Neptune – gassy, not rocky (SN Online: 12/6/11).
Astronomers are trying to determine how big a planet can be and still be rocky, not gaseous. Unfortunately, our solar system has a huge size gap between the largest rocky planet, Earth, and the smallest gaseous one, Neptune, at four times bigger. But astronomers have managed to determine both diameter and mass for a handful of exoplanets, and the early evidence supports the optimistic view that at least 62f is rocky. “We expect it to be a rocky planet,” Borucki says.
Regardless of whether 62e and 62f are vibrant worlds teeming with life or sterile balls of gas, Borucki emphasizes that Kepler still has not attained its ultimate goal of finding Earth-sized planets in the habitable zones of sunlike stars. To Borucki, 62e and 62f are slightly too big and their star slightly too small – Kepler 62 is about two-thirds the size of the sun and several hundred degrees Celsius cooler.
Finding planets in the habitable zones of larger stars will be harder because those planets have relatively long orbits and barely cast a shadow as they pass across the faces of their suns. But Kepler is beginning to identify alluring planets around larger stars like the sun, according to another study published April 18 in the Astrophysical Journal. The Kepler team, led by astronomer Thomas Barclay at NASA Ames Research Center in Moffett Field, Calif., identified two planets around a sunlike star called Kepler-69, some 2,700 light-years away in the constellation Cygnus.
One of the planets is 1.7 times the size of Earth and teeters on the inner edge of the habitable zone. It’s probably too hot for life – “It’s almost certainly a super-Venus rather than a super-Earth,” says Penn State planetary scientist James Kasting. But the planet provides another reason to believe Kepler will find an Earth analog soon.
Seager is already celebrating. “This is the first time they’ve found what they’re looking for,” she says, noting that even a planet 75 percent larger than Earth is potentially habitable. “I’m really excited to be living in a time when finding Earth-sized planets in the habitable zone is going to become routine.”
That is exactly the plan: While individual planet discoveries are nice, Kepler is a statistical mission trying to detect enough Earth analogs to estimate how many exist in our galaxy. Next-generation missions like the Transiting Exoplanet Survey Satellite, which NASA approved earlier this month for launch in 2017, will take on the task of finding nearer planets that astronomers can study in depth.
Borucki hopes Kepler will observe through 2017 to ensure a greater census of Earthlike planets. In addition, the computers that pore through Kepler data have flagged more than 350 Earth-sized candidates that have not yet been confirmed as planets. For all we know, Kepler has already found a true Earth twin that remains buried in terabytes of data.
Borucki hopes that big discovery will come within the next year. “I consider 62e and 62f golden discoveries,” he says. “But we’re hunting for platinum.”
They’re not quite Earth’s twins, but they might be its big sisters. Two planets slightly larger than Earth have been found by NASA’s Kepler space telescope. The planets circle their star at a distance seemingly just right for life. Detailed in research published April 18 in Science, the two planets are likely the first of many that, at least from a distance, look a whole lot like home.
“It’s just the tip of the iceberg,” says Sara Seager, an astronomer at MIT who was not part of the study. “When one type of object is found, there are many more just under the surface waiting to be discovered.”
Kepler’s latest discovery is a five-planet system around a star called Kepler-62, some 1,200 light-years away in the constellation Lyra. Astronomers found the planets by analyzing nearly three years’ worth of data. The inner three worlds are too hot for life, but planets Kepler-62e and Kepler-62f are far more accommodating. They are 1.6 and 1.4 times the diameter of Earth, respectively, and their orbits are within the boundaries of the habitable zone in which scientists think liquid water could exist.
“They are great candidates for being habitable planets,” says William Borucki, Kepler’s principal investigator, who came up with the idea for the planet-hunting telescope in the 1970s.
Kepler-62f is particularly intriguing, says Rory Barnes, an astronomer at the University of Washington, Seattle who was not involved in the research. It receives less energy from its star than Earth does from the sun, but if it has a relatively thick, heat-trapping atmosphere, it could sustain a comfortable surface temperature. “It’s not inconceivable to think about walking on the surface of 62f,” Borucki says.
Kepler-62e is less of a sure thing, Barnes says. It may be too close to its star – and therefore too hot – to sustain life. And if 62e is a rocky planet, it’s almost certainly tidally locked with its star, with one half of its surface always illuminated and the other perpetually dark.
But analyses from the Planetary Habitability Laboratory at the University of Puerto Rico, which evaluates the chances for life on every discovered exoplanet, disagree. The lab ranks 62e as the most Earthlike world ever found.
The biggest uncertainty about both planets is their composition. Kepler detects planets by looking for their shadows as they cross in front of their stars. Just as a golf ball and a ping-pong ball cast similar shadows, a rocky planet crossing in front of its star is indistinguishable from one composed entirely of gas or water with no solid surface.
Kepler began snagging sizzling giant planets in May 2009, almost as soon as it started staring at 170,000 stars for signs of orbiting planets. Lately the mission’s discoveries have become considerably more Earthlike. Researchers announced the discovery of the first Earth-sized worlds in December 2011, along with the first Kepler planet to orbit in its star’s habitable zone. That planet, Kepler-22b, is so large that it probably resembles a hot, miniature Neptune – gassy, not rocky (SN Online: 12/6/11).
Astronomers are trying to determine how big a planet can be and still be rocky, not gaseous. Unfortunately, our solar system has a huge size gap between the largest rocky planet, Earth, and the smallest gaseous one, Neptune, at four times bigger. But astronomers have managed to determine both diameter and mass for a handful of exoplanets, and the early evidence supports the optimistic view that at least 62f is rocky. “We expect it to be a rocky planet,” Borucki says.
Regardless of whether 62e and 62f are vibrant worlds teeming with life or sterile balls of gas, Borucki emphasizes that Kepler still has not attained its ultimate goal of finding Earth-sized planets in the habitable zones of sunlike stars. To Borucki, 62e and 62f are slightly too big and their star slightly too small – Kepler 62 is about two-thirds the size of the sun and several hundred degrees Celsius cooler.
Finding planets in the habitable zones of larger stars will be harder because those planets have relatively long orbits and barely cast a shadow as they pass across the faces of their suns. But Kepler is beginning to identify alluring planets around larger stars like the sun, according to another study published April 18 in the Astrophysical Journal. The Kepler team, led by astronomer Thomas Barclay at NASA Ames Research Center in Moffett Field, Calif., identified two planets around a sunlike star called Kepler-69, some 2,700 light-years away in the constellation Cygnus.
One of the planets is 1.7 times the size of Earth and teeters on the inner edge of the habitable zone. It’s probably too hot for life – “It’s almost certainly a super-Venus rather than a super-Earth,” says Penn State planetary scientist James Kasting. But the planet provides another reason to believe Kepler will find an Earth analog soon.
Seager is already celebrating. “This is the first time they’ve found what they’re looking for,” she says, noting that even a planet 75 percent larger than Earth is potentially habitable. “I’m really excited to be living in a time when finding Earth-sized planets in the habitable zone is going to become routine.”
That is exactly the plan: While individual planet discoveries are nice, Kepler is a statistical mission trying to detect enough Earth analogs to estimate how many exist in our galaxy. Next-generation missions like the Transiting Exoplanet Survey Satellite, which NASA approved earlier this month for launch in 2017, will take on the task of finding nearer planets that astronomers can study in depth.
Borucki hopes Kepler will observe through 2017 to ensure a greater census of Earthlike planets. In addition, the computers that pore through Kepler data have flagged more than 350 Earth-sized candidates that have not yet been confirmed as planets. For all we know, Kepler has already found a true Earth twin that remains buried in terabytes of data.
Borucki hopes that big discovery will come within the next year. “I consider 62e and 62f golden discoveries,” he says. “But we’re hunting for platinum.”
The distant, old star — located about 3,300 light-years away in the constellation Scutum — is probably billions of years old. But on a human scale, it still has a lot of life to live. The old-timer’s colorful orb will twinkle for at least 10,000 more years.
Depending on which chemicals form the gaseous shell, a star’s planetary nebula can glimmer a rainbow of candy-colored hues. For this nebula, oxygen paints the bubble a brilliant glowing green.
Bleaching strips reefs of colorful life-supporting microalgae and leaves the coral vulnerable to invasive algae and death. Scientists had thought that reefs could recover only after young new corals from neighboring, healthy reefs settled in.
But in the Scott Reef in Australia — which suffered bleaching in 1998 and stands more than 250 kilometers from other reefs — corals have grown back just fine, reports a team led by James Gilmour of the University of Western Australia Oceans Institute in Perth. Isolation may protect corals from harmful human activities, the team suggests, and allow surviving remnants to flourish.
The Alpha Magnetic Spectrometer is the latest and most ambitious attempt to uncover the identity of dark matter by looking for cosmic rays, which are charged subatomic particles cruising through space. Theoretical physicists have proposed that dark matter could be made up of exotic particles that can slam into and annihilate each other, creating detectable cosmic rays such as electrons and their antimatter partners, positrons.
This first batch of AMS results, published April 3 in Physical Review Letters, encompasses about 25 billion particles detected over the course of a year and a half, including 6.8 million measurements of the electrons and positrons that could come from dark matter. AMS improved the precision of earlier data, detected particles at higher energies than previous instruments and found that the particles arrive in equal amounts from all directions.
In the mid-1990s, physicists got a first peek at cosmic rays that could have resulted from dark matter annihilation. The High Energy Antimatter Telescope, a cosmic ray detector attached to a high-altitude balloon, found an unexpectedly high number of positrons, a result that seemed to jibe with the idea that dark matter annihilation creates these charged particles. In the last five years two space-based detectors, PAMELA, for the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics, and the Fermi Gamma-ray Space Telescope, have found even more decisive evidence of excess positrons.
Unfortunately for dark matter hunters, the specifics of the probes’ observations do not match up well with theories that predict cosmic rays resulting from dark matter annihilation. Along with electrons and positrons, dark matter annihilation should produce other signals like extra antiprotons (protons’ antimatter siblings), gamma rays and radio waves. But detectors have found no evidence of any of those signals.
Researchers hope that AMS can bring clarity to this debate because of its leg up on other cosmic ray detectors. Among other strengths, its perch aboard the International Space Station means it can sample the full spectrum of cosmic rays above Earth’s atmosphere, avoiding molecules in the air that prevent most cosmic rays from ever reaching the ground. AMS also sports a strong magnet and precise sensors that allow researchers to easily distinguish between particles that behave similarly, such as protons and positrons.
Samuel Ting, a Nobel laureate from MIT who leads the AMS experiment, is optimistic about the project’s chances. “I think there is no question we are going to solve this problem” of the positrons’ origin, he said. One clue comes from studying the abundance of positrons at very high energies, which AMS is the first to explore. In general, the number of positrons increases as their energies rise, but the new AMS data shows that at a certain point, that increase tails off.
If the number of positrons at high energies suddenly plummets, Ting said, it would suggest dark matter as a source. He said it would take at least several more months for AMS to detect enough of these high-energy particles to come to a definitive conclusion. Piergiorgio Picozza, spokesman for the PAMELA mission, eagerly awaits that announcement, saying it may bring “pleasant surprises,” he said. “We have to wait and to hope.”
Adam Falkowski, a particle physicist at the National Center for Scientific Research in Paris, is more pessimistic: “There's absolutely no way that measurements of the positron spectrum may give us a robust evidence for dark matter, not now, and not anytime soon,” he wrote on his blog.
For Ting, these results have been a long time coming. He first proposed the idea of a space-based cosmic ray detector in 1994. He kept the project alive through lobbying NASA officials and Congress during years of delays, cost overruns and the 2003 explosion of the space shuttle Columbia. Ultimately his 8,500-kilogram magnum opus made it to the International Space Station aboard the penultimate shuttle flight in May 2011.
Dark matter detection is just one of many goals for AMS. After billions more particle detections, the instrument may find antimatter nuclei that somehow survived the first few moments after the Big Bang when most of their counterparts collided with regular matter and got destroyed. Other possibilities include pinning down the source of cosmic rays within the Milky Way and finding other exotic types of matter.
Using the Hubble Space Telescope
,
scientists recently caught sight of Supernova UDS10Wil (nicknamed SN
Wilson) which exploded more than 10 billion years ago. It took more than
10 billion years for the light of this violent star explosion to reach
Earth.SN Wilson is known as a Type Ia supernova — a particular kind of star explosion that gives scientists a sense of how the universe has expanded over time.
"This new distance record holder opens a window into the early universe, offering important new insights into how these stars explode," research leader David Jones of Johns Hopkins University in Baltimore, Md., said in a statement. "We can test theories about how reliable these detonations are for understanding the evolution of the universe and its expansion." [See Amazing Pictures of Supernovas
]SN Wilson is only four percent more distant than the last most distant supernova of its kind found by Hubble, NASA officials said in a statement. However, that is still 350 million years further back in time than any other previously found star explosion.
"If supernovae were popcorn, the question is how long before they start popping?" Adam Riess, an astronomer at the Space Telescope Science Institute in Baltimore, Md., said in a statement. "You may have different theories about what is going on in the kernel. If you see when the first kernels popped and how often they popped, it tells you something important about the process of popping corn."
This work also might contribute to other work being done on what triggers these massive explosions
, a question that has plagued astronomers since the discovery of Type Ia supernovas.This discovery is also part of a three-year-initiative by the Hubble program to find the most distant supernovas. Scientists with the program hope to understand if the star explosions have changed in some way since the Big Bang birthed the universe 13.8 billion years ago.
The Hubble Space Telescope was launched in 1990. It is expected to continue functioning for the next five years or so, and its successor, the James Webb Space Telescope, is scheduled for launch in 2018.
The new findings will be published in an upcoming issue of The Astrophysical Journal.
