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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For the first time, researchers have watched weather conditions shift on a planet outside our solar system, and say the temperature spikes are out of this world. Normally, the planet is a toasty 980 degrees [Fahrenheit] or so. But in the few hours it whips around its sun the planet gets zapped with mega-heat, pushing the thermometer closer to 2,240 degrees…. When it comes closest to its star, it becomes one giant “brewing storm” [AP].
The gas giant, known as HD 80606b, lies about 190 light-years away in the constellation Ursa Major, and has an extremely elliptical orbit. When it’s closest to its sun, it is barely more than 300,000 miles away – not much more distant than our cold moon is from us. But when the planet is farthest away from its sun and coolest, it’s nearly 70 million miles away. That would be like some object flying somewhere far out between the orbits of Earth and Venus [San Francisco Chronicle]. One complete orbit around its sun takes 111 days.
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Dead stars surrounded by fields of dust from pulverized asteroids may seem to make up a forbidding and ominous picture, but researchers who studied six such star systems say the dust should actually fuel the optimism of people who dream of finding extraterrestrial life. The dust’s composition suggests that rocky planets like our own Earth may be common in the universe, researchers say, which ups the chance that life as we know it has evolved somewhere out there.
The dust in question was found surrounding small, dense white dwarf stars. As stars like our own sun near the end of their life, they puff up into red giants that consume their innermost planets and jostle the orbits of outer planets and asteroids. Eventually the stars blow off their outer layers and shrink down into white dwarfs. Occasionally, a perturbed asteroid will wander too close to the white dwarf, whose gravity rips the rocky body to shreds, forming debris [SPACE.com].
That debris is what researchers studied with NASA’s Spitzer Space Telescope. By viewing the stars through a spectrograph, which separates out light from different wavelengths, the scientists were able to observe the telltale signatures of certain chemicals in the light. Since that starlight is passing through the film of the asteroid debris, the light picked up signatures of the asteroids’ composition, too [Wired News]. Lead researcher Michael Jura announced at the ongoing American Astronomical Society meeting that the composition of the asteroid dust was remarkably similar to that of the rocky planets in our solar system.
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For the first time, carbon dioxide has been detected in the atmosphere of an exoplanet, astronomers working with the Hubble Space Telescope report. Although the Jupiter-sized planet, which closely orbits the star HD 189733 about 63 light-years from Earth, is much too hot to support life, scientists are hailing the discovery as an exciting technical achievement. “In that context, the carbon dioxide measurement constitutes a dress rehearsal …for our long-term goal of trying to detect signs of life or signs of habitability on terrestrial-mass planets or super Earths in the habitable zone,” [Science News] says Mark Swain of NASA’s Jet Propulsion Laboratory.
Researchers deduced the presence of carbon dioxide by measuring the planet’s light spectrum with the Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS). To isolate the light spectrum coming from the planet, researchers used a method known as “secondary transit.” This involves recording the light spectrum of the planet and its star, and then measuring the spectrum of the star alone while the planet is hidden behind it. The difference of the two spectra is the spectrum of the light coming directly from the planet [Nature News]. Unlike previous measurements that focused on the mid-infrared range, NICMOS took measurements in the near-infrared range, enabling detection of the carbon dioxide signature.
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The evolution of minerals on our planet has been propelled by the evolution of life on earth, a sweeping new study demonstrates. While the underlying assumption isn’t new, the study is the first to chart how the emergence of algae and then complex microorganisms gave rise to the 4,300 or so minerals that are now present on earth.
In the early days of the universe, clouds of gas and dust contained all the naturally occurring elements found in the periodic table, but most were too widely dispersed to form minerals; scientists believe there were only about a dozen minerals in the interstellar medium. According to the study, around a further 60 different minerals formed 4.5 billion years ago, as clumps of matter collided and coalesced to begin forming the Solar System. The smaller fragments congealed into larger, planet-sized bodies, where volcanism and the effects of water took the mineral count into the hundreds. The planets Mars and Venus have got this far [Nature News], and have minerals created by hot magma like quartz and zircon.
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In news that has thrown astronomers and space enthusiasts into a tizzy of excitement, two separate research teams announced today that they have taken the first pictures of exoplanets, planets orbiting stars beyond the edge of our solar system. It’s an achievement that has long been considered vital in the search for planets like our own [Physics World].
One team spotted a single planet circling a bright star only 25 light-years away in the constellation Piscis Austrinus, while the other detected three giant planets orbiting a star 130 light-years away in the Pegasus constellation.
More than 300 so-called extrasolar planets have been found circling distant stars, making their discovery the hottest and fastest growing field in astronomy. But the observations have been made mostly indirectly, by dips in starlight as planets cross in front of their home star or by wobbles they induce going by it. Astronomers being astronomers, they want to actually see these worlds, but a few recent claims of direct observations have been clouded by debates about whether the bodies were really planets or failed stars [The New York Times]. But these newly discovered celestial objects are the right size for planets, and were observed moving around their parent stars.
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Astronomers believe they’ve found evidence of a massive collision between two planets in a mature solar system, shaking theories that such pileups only occur in young systems where planetary orbits aren’t yet stabilized. Says lead researcher Benjamin Zuckerman: “It’s as if Earth and Venus collided with each other…. Astronomers have never seen anything like this before; apparently major, catastrophic, collisions can take place in a fully mature planetary system” [Reuters].
Researchers base their theory on observations of vast clouds of dust and debris in a binary star system 300 light years away in the Aries constellation. Initially, they had a different idea about why the system contains 1 million times more dust that our own solar system: They had assumed it was a young star, just a few hundred million years old, and the debris was leftovers from planet formation. But earlier this year, another study showed the star was actually a binary pair, and that the stars were billions of years old [SPACE.com]. That finding forced astronomers to rethink what could have caused the dust; in older systems, most debris has either been consolidated into planets or pushed away by solar winds.
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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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