On Friday night, a Delta 2 rocket blasted off from the Kennedy Space Center and roared into space carrying a satellite that will search the heavens for Earth-like planets. The craft, Kepler, named after the German astronomer Johannes Kepler, who discovered the planetary laws of motion, is to spend the next three and a half years in an orbit around the Sun, where it will count planets by looking for the tiny blips in starlight caused by planets eclipsing their suns [The New York Times].
The $600 million satellite will stare into a region of the Milky Way that’s thick with stars, in the direction of the constellations Cygnus and Lyra. While Kepler is expected to identify many new planets beyond our solar system, known as exoplanets, the real prize would be to find rocky planets in the “habitable zone” around a star, where conditions might be right for life as we know it. “The habitable zone is where we think water will be,” Bill Borucki, Kepler principal investigator at NASA Ames, says in a video on the space agency’s Kepler site. “If you can find liquid water on the surface we think we may very well find life there. So that zone is not too close to the star, because it’s too hot and water boils, and not too far away where the water is condensed…a planet covered with glaciers. It’s the Goldilocks zone–not too hot, not too cold, just right for life” [CNET].
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While astronomers have found more than 300 planets beyond our solar system in the last 15 years, none of those “exoplanets” has been a likely candidate for extraterrestrial life. The exoplanets discovered thus far are all either too close to the hot sun or too far away and therefore too frigid to host life as we know it. But Alan Boss says it’s just a matter of time before we find Earth-like planets in the “Goldilocks zone”: he calculates that 100 billion of them may exist within our own Milky Way galaxy. And NASA’s Kepler satellite, which is expected to launch on March 5, may be the key to finding them, he says.
Boss, an astrophysicist and author of the new book “The Crowded Universe: The Search for Living Planets,” says that if any of the billions of Earth-like worlds he believes exist in the Milky Way have liquid water, they are likely to be home to some type of life. “Now that’s not saying that they’re all going to be crawling with intelligent human beings or even dinosaurs,” he said. “But I would suspect that the great majority of them at least will have some sort of primitive life, like bacteria or some of the multicellular creatures that populated our Earth for the first 3 billion years of its existence” [CNN].
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A rocky world about twice the size of Earth has been detected orbiting a sun-like star 390 light years away from our solar system. While the “super-Earth” is hot and inhospitable to life as we know it, its discovery puts researchers firmly on the path towards finding other habitable planets. “For the first time, we have unambiguously detected a planet that is ‘rocky’ in the same sense as our own Earth” [Wired News], said project scientist Malcolm Fridlund. The exciting find was made by the CoRoT satellite, which was launched by the French space agency to scan the skies for exoplanets (planets outside our solar system). The results were announced at a CoRoT symposium in Paris.
CoRoT team member Suzanne Aigrain explains that the planet is so close to its parent star that it orbits around it once every 20 hours, and is subject to inferno-like conditions. “It’s likely that there is a solid surface somewhere,” says Aigrain. But the extreme surface temperatures of around 1000°C [around 1800 degrees Fahrenheit] could mean that the planet is host to vast lava fields and boiling oceans. It also may be ‘tidally locked’ to its parent star, leaving one face bathed in constant, searing sunlight while the other is shrouded in continuous night. “It would be a very odd place to set foot on,” she says [Nature News].
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The nearest planetary system to our own has two asteroid belts in addition to a previously known ice belt, according to the latest observations by NASA’s Spitzer Space Telescope. The location and structure of the asteroid belts relative to the system’s central star, Epsilon Eridani, suggests the existence of earth-like planets. “We certainly haven’t seen it yet, but if its solar system is anything like ours, then there should be planets like ours,” says astronomer Massimo Marengo of the Harvard-Smithsonian Center for Astrophysics [USA Today].
The Epsilon Edidani system has long been of interest to astronomers and science fiction fans alike because of its proximity (10.5 light-years) and resemblance to our solar system. The newly discovered asteroid belts give the system an appearance even more like our own. The inner asteroid belt looks identical to ours in terms of material, and it orbits at 3 astronomical units (AU) from Epsilon Eridani — the same distance between the sun and the rocky asteroid belt between Mars and Jupiter. (An astronomical unit equals the average Earth-sun distance of 93 million miles, or about 150 million km.) Epsilon Eridani’s second asteroid belt is 20 AU from the star, or about where Uranus is in relation to our sun, and it is crowded with as much mass as Earth’s moon [Science News]. The outer asteroid belt was captured directly by Spitzer’s infrared cameras and the inner asteriod belt, though too far from the cameras, was indicated by the thermal energy from its infrared emissions.
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Astronomers think they have taken the first picture ever of a planet orbiting a star very similar to our own sun. However, the new planet itself appears to be quite different from our Earth. Located around 500 light-years from Earth, the planet in the snapshot is around eight times bigger than Jupiter, the biggest in our solar system and lies more than ten times further from its star than the sun does from Neptune [Telegraph]. Researchers were surprised to discover that the planet orbits at such a distance from its star, and say the discovery could upend accepted theories of planet formation.
The researchers say they’ll keep studying the object they spotted to confirm that the planet is in fact orbiting around the star, as opposed to the possibility, however unlikely, that the two objects just happen to lie in the same area of the sky at roughly the same distance from us. “Of course it would be premature to say that the object is definitely orbiting this star, but the evidence is extremely compelling,” [lead researcher David] Lafrenière said [SPACE.com].
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It may be getting old hat for some astronomy researchers, but the discovery of new exoplanets—planets orbiting stars far from our little solar system—can still send a shiver of excitement through space buffs. And today was a jackpot, as European researchers announced that they’d found a trio of “super-Earths” that are only slightly larger than our own planet, and that the three are all orbiting the same star 42 light years away.
They said their findings, presented at a conference in France, suggest that Earth-like planets may be very common. “Does every single star harbour planets and, if yes, how many?” asked Michel Mayor of Switzerland’s Geneva Observatory. “We may not yet know the answer, but we are making huge progress towards it,” Mayor said in a statement [New Scientist].
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In a solar system far, far away, around a small and dim star, orbits a small planet, just three times the size of Earth.
The astronomers who discovered the small planet don’t know much else about it yet, but the basics are enough to get them excited. Extraterrestrial life is thought to have the best chance of surviving on planets with a similar mass to that of Earth, orbiting small stars.
This “exoplanet,” which goes by the romantic name MOA-2007-BLG-192Lb, is the second smallest planet ever spotted outside our solar system. The very smallest planet yet discovered is believed to be sterile, as it orbits a neutron star that emits blasts of radiation.
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