Astronomers have conclusive evidence that a planet spotted in a star system 500 light years away is rocky and solid, just like Earth. Scientists have long figured that if life begins on a planet, it needs a solid surface to rest on, so finding one elsewhere is a big deal. “We basically live on a rock ourselves,” said co-discoverer Artie Hartzes…. “It’s as close to something like the Earth that we’ve found so far. It’s just a little too close to its sun” [AP].
Yes, for while the exoplanet, Corot-7b, is rocky like Earth and is only about five times more massive than our home planet, it’s hardly our twin. Its close proximity to its star means that it completes an orbit (its “year”) in just 20 hours, and the climate extremes are punishing. Temperatures soar above 2,000 degrees on its day side and sink to minus 200 degrees on the night side. It means the surface could be covered with molten lava or boiling oceans and it certainly could not hold any form of life as we know it [Scientific American].
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In a star system 330 light years away from Earth, astronomers have spotted a giant planet that booms around its parent star in tight, fast circles, completing an orbit (the planet’s “year”) in less than one Earth day. The exoplanet, known as Wasp-18b, is so close to its star that researchers say it appears to be spiraling inwards to its fiery doom. But the odds of seeing a planet in its death throes are so low that researchers are searching for alternate explanations, and say the planet could force scientists to rethink established ideas about planetary forces known as tidal interactions [National Geographic News].
The planet is known as a “hot Jupiter,” meaning that it’s a massive gas giant like our own solar system’s Jupiter, but it orbits in close proximity to its star. Current theories say that such a massive planet so close to its star should be pulling on the host star, creating a tidal effect similar to the moon’s pull on Earth. At that range the planet’s pull would be so strong that it would drain energy from its orbit, causing the planet to rapidly fall into the star [National Geographic News]. But if that’s the case, the planet would meet its death in less than a million years. Since the star system is thought to be about 1 billion years old, the odds of catching the planet in its last stages are one in a thousand.
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Scientists have spied a new exoplanet–and not only is it the biggest one yet, but it’s also moving the wrong direction. Unlike other planets, which orbit the same way their stars rotate, WASP-17 moves the opposite way, according to a study published in Astrophysical Journal.
Planets are born from the same ball of rotating gas that creates their parent star, which is why they usually orbit — and spin — in the same direction as their star. While WASP-17 is the first planet known to orbit backwards, some planets in our own solar system, such as Venus, are spinning backwards [Wired]. WASP-17′s backwards motion is known by astronomers as a retrograde orbit.
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NASA’s Kepler spacecraft has only been in operation for 10 days, but it’s already spotted a planet, according to a report in Science. That leaves experts optimistic about the craft’s potential to find other Earth-like planets.
Scientists already knew that the planet Kepler found existed. It’s called HAT-P-7b, and it’s a planetary body that’s too heavy and too hot to support life. Still, Kepler gave scientists new details about the planet, including that the planet has a hazy, ozone-like atmosphere. The analysis proves that Kepler’s onboard telescope and light-detecting instruments are at least 100 times more precise than the ground-based detectors that originally found HAT-P-7b [L.A. Times], because Earth-based telescopes must wrestle with distortion from the atmosphere, while Kepler only looks through the clear near-vacuum of space.
Scientists say that Kepler’s capabilities should be sufficient to find Earth-like planets in the “habitable zone” of a star system–that is, the ring where temperatures climb high enough to allow liquid water to exist, but aren’t so scorching as to burn up the surface of the planet.
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Only 20 years ago, astronomers were arguing over whether a colleague had discovered the first exoplanet–a planet beyond our solar system that is in orbit around an alien sun. Fast forward to the present day, and researchers have now spotted more than 300 exoplanets in our Milky Way galaxy, and the new topic of discussion is whether a group of astronomers has detected the first extragalactic planet in the Andromeda galaxy.
A new study to be published in the Monthly Notices of the Royal Astronomical Society explains that it should be possible to identify extragalactic planets with the technique of gravitational microlensing, in which a distant source star is briefly magnified by the gravity of an object passing in front of it. This technique has already found several planets in our galaxy, out to distances of thousands of light years. Extending the method from thousands to millions of light years won’t be easy, says [study coauthor] Philippe Jetzer, … but it should be possible [New Scientist]. In fact, it may have already been accomplished.
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By pretending to observe the sunlight shining through the Earth’s atmosphere from the vantage point of the moon, astronomers have gained a clue that may help them in the search for Earth-like exoplanets that could be harboring life.
The astronomers made their observations on 16 August 2008 during a lunar eclipse — in which the Moon moves into Earth’s shadow. Even when the Moon is totally eclipsed by Earth, it is still bathed in a dim red light — from sunlight that has been bent as it passes through the edge of Earth’s atmosphere. Using Earth-based telescopes, the astronomers detected some of this light after it bounced back from the Moon [Nature News].
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Planet-hunters have yet another tool to use in their quest to discover distant worlds that could harbor life. A group of astronomers has discovered a gas giant with six times the mass of Jupiter orbiting a small, weak red dwarf star by means of a method called astrometry. It’s the first time researchers have spotted an exoplanet with this technique, which they say could be useful for finding a different type of planet than those detected by tried and true methods.
Most of the 300-plus known extrasolar planets have been found by tracking changes in a star’s light output over time. The most prolific approach, the radial velocity method, looks for shifts in that light caused by the Doppler effect as the tug of an orbiting planet pulls the star nearer and more distant to us along our line of sight. The other approach, the transit method, tracks the periodic dimming of a star caused by a planet passing in front of it [Scientific American]. In contrast, astrometry doesn’t focus on a star’s light output, but rather on its precise location.
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Water is crucial to the only kinds of living things we’ve ever seen, so the presence of the wet stuff on another planet could be a sign of potential life. Unfortunately, scientists have been unsure how to detect water on distant planets. But the Deep Impact spacecraft has recently given researchers a glimpse of what a wet planet looks like from far away by turning its detectors onto the Earth itself.
Essentially, Deep Impact has turned Earth into a case study of a planet replete with water. The spacecraft, which is 30 million miles away, or halfway to Venus from Earth, has shown scientists how overlapping continents and bodies of water alter the way that light of seven different wavelengths reflects off of the planet’s surface. When scientists observed light from Earth twice over a 24-hour period, they found small deviations in colour caused when clouds or oceans rotated into view. The results mean they should now be able to recognise similar features on alien planets using giant telescopes in space [Scientific American].
The researchers were able to identify key features that could help identify a water-laden planet using telescopes, chemical-analyzing spectrographs and other instruments…. As Earth completed a 24-hour rotation, the change in brightness varied by about 30 percent up and down. The shift is caused by the planet’s reflectivity as the sun [alternately] shines on oceans and then continents [Discovery News]. The findings will be published in an upcoming issue of Astrophysical Journal.
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Four hundred years ago, Galileo observed the phases of Venus as the planet orbited our sun and caught its light in different ways, helping to disprove the idea that all celestial bodies twirled around the Earth. Now, the professional descendants of Galileo have observed the phases of an exoplanet for the first time, observing the distant planet in the act of orbiting a foreign star.
The planet, CoRoT-1b, is about 1,600 light years away from Earth, and was discovered about 2 years ago. It’s a “hot Jupiter,” a class of exoplanets that are the size of Jupiter but orbit very closely to their stars (CoRoT-1b orbits its star in just 36 hours). Hot Jupiters are expected to be tidally locked, with one side always facing their stars, the other permanently dark (our own moon is tidally locked with the Earth, only showing its “near side” to us) [SPACE.com].
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Astronomers still haven’t discovered Earth’s twin orbiting another star out in the cosmos, but they’re beginning to find worlds with a passing resemblance to our own. New studies of the red dwarf star Gliese 581 have revealed a small, rocky exoplanet with only twice the mass of Earth, and have also shed new light on a larger planet orbiting farther out, which researchers now say could have liquid water. Team member Stephane Udry believes that the larger planet could have a “large and deep” ocean. “It is the first serious ‘water-world’ candidate,” Udry said [AP].
Researchers had previously discovered three planets orbiting the star, including the potential water world, Gliese 581 d. Based on earlier observations, researchers thought that the planet took 83 days to orbit its star, which would indicate that the planet was too far from the red dwarf’s weak heat to have liquid water. But more extensive observations have shown that the planet actually has an orbital period of 66 days, putting the planet just inside the star’s “habitable zone.” Lead researcher Michel Mayor says the planet may be warm enough to bear oceans that are thousands of miles deep. “Maybe this is the first of a new class of ocean planets. That is my favourite interpretation,” says Mayor. “Whether there is life or not, I don’t know” [New Scientist]. However, not everyone is convinced that Gliese 581 d is wet and wild. Other experts say it’s more likely to be an ice giant, like Neptune and Uranus.
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The Kepler space telescope, which was launched in early March, has taken and sent home its first images of the region in the galaxy where it will spend the next three years searching for Earth-like planets.
The images sent to NASA show a “vast starry field” in the Cygnus-Lyra region of the Milky Way galaxy, according to NASA’s Jet Propulsion Laboratory. One image shows millions of stars in the craft’s full field of view, while two other images zoom in specific sections of that region [Computerworld]. Kepler’s primary mission is to survey stars for regular slight dips in their brightness, a sign that an orbiting planet is blocking the star’s light [Nature blog]. Eventually, the craft will measure the stars’ brightness every half hour.
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The first ever picture of an exoplanet was taken 11 years ago–but no one noticed. Now, in a new study, astronomers have subtracted the starlight from an image taken by the Hubble in 1998, and found the exoplanet by its dim infrared glow. While some exoplanets were detected before 1998, they were discovered indirectly by observing their influence on their parent stars; this was was seen directly.
The new technique has excited researchers wondering how many more new planets can be found in old, archived data. “They’ve dug up old Hubble images and found a planet! Crazy!” Geoff Marcy, an astronomer at the University of California, Berkeley, commented by email. “This will spawn a wild race by astronomers everywhere in the world to dig out their old Hubble images to hunt for planets lost in the rubble of the Hubble” [National Geographic News].
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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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