New Earth-like Planet Spotted Just 44 Light Years Away

Boris Pavlishev: A team of British and German space scientists using ground-based telescopes in Chile have spotted an Earth-like planet revolving around a Sun-type star just about 44 light hours away from our solar system. The newly-discovered planet is believed to have atmospheric and other conditions that make it very similar to Earth. Of all the Earth-like planets found to date, it’s the closest to us. 
More than 800 planets have been discovered outside the solar system over the past two decades, the majority of them being gas giants like Jupiter or solid planets too close to their stars and therefore too hot to support water. The new planet is in the so-called “habitable zone”, which means that it may have water in a liquid state, and it also has an axis of rotation. The latter increases chances that it may support Earth-type life, says astrophysicist Sergei Smirnov of Russia’s Pulkovo Observatory. "It’s important that its rotation should not be synchronous like that of our Moon, which is a reason why only one side of the Moon permanently faces Earth. And also, its revolution period or the length of year should differ from its rotation period or the length of day. This is an additional factor that helps sustain a biosphere. The light-and-shadow cycle and the temperature cycle are also very important. Humans are accustomed to a change of light. We can equally endure full darkness and blistering sun on a sand beach or snowfield. The same is true of cold and heat. Some living organisms can survive in a far wider range of temperatures." The new planet is 7 times the size of Earth. Higher gravity, though unlikely to affect the climate, could result in smaller forms of life, says Sergei Smirnov. "Suppose, advanced forms of life emerge there, like elephants here on Earth. Then, in all probability, they would be smaller and flatter due to higher gravity. There would be no large species." Oleg Malkov, a laboratory head at the Russian Institute of Astronomy, believes that the presence of a biosphere does not necessarily require Earth-like conditions. "There is only one type of life in the Universe that we know of – our own. Therefore, we are looking for planets that resemble Earth in mass, size, distance from the central star and all other parameters. Thus, chances that Earth-type life does exist are increasing. But life may have other forms." Sergei Smirnov agrees: "The “habitability” theories are based on scientific discoveries made in the mid-20th century. Today, we should take a broader look at potential forms of life in various temperature ranges, and in planetary atmospheres, oceans and solid surfaces of various chemical composition. In the solar system, moons of giant planets are likelier to have some forms of life than Mars. For example, Europa the size of our Moon has a thick ice shell that can possibly hold the largest amounts of liquid water in the solar system, where life is possible." Theoretically, there may be sulphuric-phosphate and silicon forms of life that do not require an atmosphere with a high concentration of oxygen. Incidentally, spectroscopic studies of exoplanets show that their atmospheres are oxygen-free. Source: Voice of Russia
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Extreme Life Forms Might be Able to Survive on Eccentric Exoplanets

Astronomers have discovered a veritable rogues' gallery of odd exoplanets -- from scorching hot worlds with molten surfaces to frigid ice balls. And while the hunt continues for the elusive "blue dot" -- a planet with roughly the same characteristics as Earth -- new research reveals that life might actually be able to survive on some of the many exoplanetary oddballs that exist. "When we're talking about a habitable planet, we're talking about a world where liquid water can exist," said Stephen Kane, a scientist with the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena. "A planet needs to be the right distance from its star -- not too hot and not too cold." Determined by the size and heat of the star, this temperature range is commonly referred to as the "habitable zone" around a star. Kane and fellow Exoplanet Science Institute scientist Dawn Gelino have created a resource called the "Habitable Zone Gallery." It calculates the size and distance of the habitable zone for each exoplanetary system that has been discovered and shows which exoplanets orbit in this so-called "goldilocks" zone. The Habitable Zone Gallery can be found a thttp://www.hzgallery.org . The study describing the research appears in the Astrobiology journal and is available at http://arxiv.org/abs/1205.2429 . But not all exoplanets have Earth-like orbits that remain at a fairly constant distance from their stars. One of the unexpected revelations of planet hunting has been that many planets travel in very oblong, eccentric orbits that vary greatly in distance from their stars. "Planets like these may spend some, but not all of their time in the habitable zone," Kane said. "You might have a world that heats up for brief periods in between long, cold winters, or you might have brief spikes of very hot conditions." Image above: A hypothetical planet is depicted here moving through the habitable zone and then further out into a long, cold winter. Image credit: NASA/JPL-Caltech. Though planets like these would be very different from Earth, this might not preclude them from being able to support alien life. "Scientists have found microscopic life forms on Earth that can survive all kinds of extreme conditions," Kane said. "Some organisms can basically drop their metabolism to zero to survive very long-lasting, cold conditions. We know that others can withstand very extreme heat conditions if they have a protective layer of rock or water. There have even been studies performed on Earth-based spores, bacteria and lichens, which show they can survive in both harsh environments on Earth and the extreme conditions of space." Kane and Gelino's research suggests that habitable zone around stars might be larger than once thought, and that planets that might be hostile to human life might be the perfect place for extremophiles, like lichens and bacteria, to survive. "Life evolved on Earth at a very early stage in the planet's development, under conditions much harsher than they are today," Kane said. Kane explained that many life-harboring worlds might not be planets at all, but rather moons of larger, gas-giant planets like Jupiter in our own solar system. "There are lots of giant planets out there, and all of them may have moons, if they are like the giant planets in the solar system," Kane says. "A moon of a planet that is in or spends time in a habitable zone can be habitable itself." As an example, Kane mentioned Titan, the largest moon of Saturn, which, despite its thick atmosphere, is far too distant from the sun and too cold for life as we know it to exist on its surface. "If you moved Titan closer in to the sun, it would have lots of water vapor and very favorable conditions for life." Kane is quick to point out that there are limits to what scientists can presently determine about habitability on already-discovered exoplanets. "It's difficult to really know about a planet when you don't have any knowledge about its atmosphere," he said. For example, both Earth and Venus experience an atmospheric "greenhouse effect" -- but the runaway effect on Venus makes it the hottest place in the solar system. "Without analogues in our own solar system, it's difficult to know precisely what a habitable moon or eccentric planet orbit would look like." Still, the research suggests that habitability might exist in many forms in the galaxy -- not just on planets that look like our own. Kane and Gelino are hard at work determining which already-discovered exoplanets might be candidates for extremophile life or habitable moons. "There are lots of eccentric and gas giant planet discoveries," Kane says. "We may find some surprises out there as we start to determine exactly what we consider habitable." NASA's Exoplanet Science Institute at Caltech manages time allocation on the Keck Telescope for NASA. NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages NASA's Exoplanet Exploration program office. Caltech manages JPL for NASA. More information about exoplanets and NASA's planet-finding program is at http://planetquest.jpl.nasa.gov . Image, Text, Credits: NASA / JPL-Caltech / Written by Josh Rodriguez. Greetings, Source: Orbiter.ch Space News
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