NASA's Kepler Spacecraft Discovers Eight New Earth-Like Exoplanets In 'Goldilocks Zone'
Eight New Earth-Like Planets Discovered By Nasa
Paul Vale— PA/Huffington Post UK
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Eight more planets have been discovered that could possess watery oceans and life, including two of the most Earth-like yet found. The new worlds double the number of small exoplanets believed to be circling their stars in the "habitable zone" - the narrow region in which temperatures are mild enough to allow liquid surface water and perhaps even life.
By "small" astronomers mean planets with less than twice the Earth's diameter. "Most of these planets have a good chance of being rocky, like Earth," said lead scientist Dr Guillermo Torres, from the Harvard-Smithsonian Centre for Astrophysics in Cambridge, US.
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Artist's impression of an Earth-like planet orbiting a star near the end of its life surrounded by a shell of expanding gas
The two most Earth-like planets, known as Kepler-438b and Kepler-442b, both orbit red dwarf stars that are smaller and cooler than the Sun. With a diameter just 12% bigger than Earth, Kepler-438b has a 70% chance of being rocky, the scientists have calculated. Kepler-442b is about one-third larger than Earth, and the likelihood of it being rocky is around 60%.
To be in the habitable zone, also known as the "Goldilocks zone", a planet must be not too hot or too cold and receive roughly as much sunlight as Earth. Too much heat from its star, and any water would boil away as steam. Too little, and the water would freeze solid.
"For our calculations we chose to adopt the broadest possible limits that can plausibly lead to suitable conditions for life," Dr Torres added. Kepler-438b receives about 40% more light than the Earth giving it a 70% probability of having a habitable zone orbit. In comparison, baking hot Venus has twice as much.
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Illustrations of the newfound exoplanets pictured next to Earth. Click on the image to enlarge
The other star gets about two-thirds as much light as Earth and is 97% likely to be in the habitable zone. Co-author Dr David Kipping, also from the Centre for Astrophysics, said: "We don't know for sure whether any of the planets in our sample are truly habitable. All we can say is that they're promising candidates."
Neither of the planets are our close neighbours. Kepler-438b is located 470 light-years from Earth while the more distant Kepler-442b is 1,100 light-years away. The team, whose findings were presented at the American Astronomical Society's annual meeting in Washington DC, studied planetary candidates first identified by the US space agency Nasa's Kepler space telescope.
All the planets were too small to confirm by measuring their masses. Instead, they were validated using a computer program that determined they were statistically likely to be planets. After the analysis, follow-up observations showed that four of the planets were in multiple star systems.
The eight discoveries are just the latest in a series of exoplanets found by the spacecraft. Since launching in 2009, Kepler has found 1,004 confirmed planets along with 4,175 planet candidates.
The research is also published in the Astrophysical Journal.
Artists' Conceptions Of Extrasolar Planets
NASA's Kepler Mission Discovers Planet(01 of05)
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In this handout illustration made available on December 5, 2011 by NASA, the Kepler-22b, a planet known to comfortably circle in the habitable zone of a sun-like star is digitally illustrated. For the first time NASA's Kepler mission has confirmed a planet to orbit in a star's habitable zone; the region around a star, where liquid water, a requirement for life on Earth, could persist. The planet is 2.4 times the size of Earth, making it the smallest yet found to orbit in the middle of the habit. Clouds could exist in this earth's atmosphere, as the artist's interpretive illustration depicts. (Photo Illustration by Ames/JPL-Caltech/NASA via Getty Images) (credit:Getty)
NASA's Kepler Mission Discovers Planet(02 of05)
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In this handout illustration made available on December 5, 2011 by NASA, a diagram compares our own solar system to Kepler-22, a star system containing the first 'habitable zone' planet discovered by NASA's Kepler mission. The habitable zone is the sweet spot around a star where temperatures are right for water to exist in its liquid form. Liquid water is essential for life on Earth. The diagram displays an artist's rendering of the planet comfortably orbiting within the habitable zone, similar to where Earth circles the sun. Kepler-22b has a yearly orbit of 289 days. The planet is the smallest known to orbit in the middle of the habitable zone of a sun-like star and is about 2.4 times the size of Earth. (Photo Illustration by Ames/JPL-Caltech/NASA via Getty Images) (credit:Getty)
Extrasolar Planet HD 209458 b, Osiris(03 of05)
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Artist's conception released by NASA of extrasolar planet HD 209458 b, also known as Osiris, orbiting its star in the constellation Pegasus, some 150 light years from Earth's solar system. Scientists have used an infrared spectrum -- the first ever obtained for an extrasolar planet -- to analyze Osiris' atmosphere, which is said to contain dust but no water. The planet's surface temperature is more than 700 Celsius (1330 Fahrenheit).' (credit:Getty)
Planet & Its Parent Star(04 of05)
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Picture released 04 October 2006 by the European Space Agency shows an artist's impression of a Jupiter-sized planet passing in front of its parent star. Such events are called transits. When the planet transits the star, the star's apparent brightness drops by a few percent for a short period. Through this technique, astronomers can use the Hubble Space Telescope to search for planets across the galaxy by measuring periodic changes in a star's luminosity. The first class of exoplanets found by this technique are the so-called 'hot Jupiters,' which are so close to their stars they complete an orbit within days, or even hours. A seam of stars at the centre of the Milky Way has shown astronomers that an entirely new class of planets closely orbiting distant suns is waiting to be explored, according to a paper published 04 October 2006. An international team of astronomers, using a camera aboard NASA's Hubble telescope, delved into a zone of the Milky Way known as the 'galactic bulge', thus called because it is rich in stars and in the gas and dust which go to make up stars and planets. The finding opens up a new area of investigation for space scientists probing extrasolar planets - planets that orbit stars other than our own. AFP PHOTO NASA/ESA/K. SAHU (STScI) AND THE SWEEPS SCIENCE TEAM (credit:Getty)
Hot Jupiter(05 of05)
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Picture released 04 October 2006 by the European Space Agency shows an artist's impression of a unique type of exoplanet discovered with the Hubble Space Telescope. This image presents a purely speculative view of what such a 'hot Jupiter' (word dedicated to planets so close to their stars with such short orbital periods) might look like. A seam of stars at the centre of the Milky Way has shown astronomers that an entirely new class of planets closely orbiting distant suns is waiting to be explored, according to a paper published 04 October 2006. An international team of astronomers, using a camera aboard NASA's Hubble telescope, delved into a zone of the Milky Way known as the 'galactic bulge', thus called because it is rich in stars and in the gas and dust which go to make up stars and planets. The finding opens up a new area of investigation for space scientists probing extrasolar planets - planets that orbit stars other than our own. AFP PHOTO NASA/ESA/K. SAHU (STScI) AND THE SWEEPS SCIENCE TEAM (credit:Getty)