At the AAS meeting, the discovery team announced that all three planets orbiting KOI-961 whip around the star in less than two days. The outermost body is the tiniest, with a diameter half that of Earth, or about the same as Mars, and a temperature of about 400 degrees Celsius. The inner two planets are larger, with diameters about three-fourths that of Earth. But that is still smaller than Venus. Because the planets are all small and close to their star, much of the atmosphere they may once have had would have evaporated, leaving behind bare rock, Marcy says.
Marcy calculates that Kepler could find planets around dwarf stars that are even smaller — with a diameter only 20% that of Earth, smaller than our Moon.
Unearthing answers
Finding a multitude of rocky, Mars-sized exoplanets may help shed light on a long-standing problem in understanding the formation of the inner Solar System, comments Dimitar Sasselov, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, who was not part of the study. Scientists have no clear explanation for why Mars, which lies outside the orbits of Venus and Earth, is so much smaller than its siblings.
The diminutive planetary trio is just the latest in a flurry of discoveries by Kepler. In December, researchers reported that the orbiting telescope had found the first known Earth-sized planets beyond the Solar System, although these bodies were also too hot for water to exist on its surface. Scientists also reported last month that the craft had found its first exoplanet in the habitable zone — although in that case, the orb is much bigger than Earth.
The new findings demonstrate that “Kepler is surely robust at finding truly Earth-sized planets,” says Marcy. The next goal, he notes, is the mission’s reason for being: “to find an Earth-sized planet that is lukewarm, where water would be in liquid form to host biology.”
This article is reproduced with permission from the magazine Nature. The article was first published on January 11, 2012.
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Add CommentThe article states:
Reply | Report Abuse | Link to this"And because red dwarfs are the most common type of star in the Milky Way, the finding suggests that the Galaxy may be teeming with rocky planets — with at least some residing in the 'habitable region' around those stars, where the temperature would be just right for water to remain liquid and life might have got a foothold."
I understand that binary star systems are thought to be more common than single stars, and that planets are less likely to achieve stable orbit in a binary star system. While these observations of planets orbiting dwarf stars might have been able to estimate planets' orbital period and stellar proximity, its most likely that more distant orbits would be somewhat elliptical. I'd guess that an elliptical orbit averaging more than one AU around a dwarf star would produce some extreme seasonal climate variations, perhaps even completely freezing all water in the winter and evaporating it in the summer. An exoplanetary system of a dwarf star with planets in its 'goldilocks' zone with abundant water might not provide conditions stable enough to develop complex life forms.
Also, Earth's single, relatively large moon is thought to provide rotational stability that is thought to be crucial to the development of complex life forms.
Even if we find exoplanets in the golilocks zone of Sun-like planetary systems, unless intelligent life forms transmit a signal to us, how will we ever be able to determine whether life exists there? We can't even determine whether or not life exists on some of our best candidate, neighboring planets' moons!
Frankly, I think that astronomers are investing too much of our limited resources in the discovery of planets that, while they certainly offer fertile fields of study, will never provide any really useful benefit to humanity. What fun we're having, though! Just imagine colonizing a whole bunch of new Edens! By all means - we must find every planet!
Trouble is even if we find what will essentially be seen as another earth - it may be too far away to conceivably travel to or communicate with.
Reply | Report Abuse | Link to thisSuppose we do discover such a planet and could afford to send a probe to it - the probe might not even reach its destination within our lifetime - and even when it got there, it might only find bacteria.
Is that worth spending billions of dollars on? As a tax payer, I need a stronger reason than "what if?"
Did you need a stronger reason to invade Iraq than they might have WMDs? As a tax payer and a voting member of a hypothetically democratic society it is your responsibility to educate yourself on these issues. Having a strong opinion about something you know nothing about does no one any good. Do you have any appreciation of how this research creates technology spin-offs that make their way into consumer goods? Are you so eager to give up the lead in cosmology to other nations? China and India are moving ahead in space research, they would gladly take the lead. Then again, the right wing nut jobs who whine about their tax dollars being wasted on science when instead they could be wasted on bombing developing nations into oblivion or funnelled into the pockets of the obscenely rich, have no interest in science. The good lord tells them everything they need to know which they promptly ignore when it is inconvenient. If that is the case, you are on the wrong website. I'm sure there are places for those who prefer greed over knowledge.
Reply | Report Abuse | Link to thisWe do not need to survey every inch of every new planet before Cortez lands an expedition on one and sets up a new colony. Let's hope he does not kill a Montezuma in the process.
Reply | Report Abuse | Link to thisWe might be able to create an ion drive in place of a chemical rocket. That would make an unmanned round trip rocket to a nearby star possible within my lifetime. I might see a planet where a great great grandchild might live.
Robert Schmidt, right on the money, that's the answer. Thank You!!
Reply | Report Abuse | Link to thisNot likely. Even if we could build a propulsion system which might get us up to 10% of the speed of light (doubtful with present technology), and if it were ready to launch now, it would still take at least eighty years for the round trip to the nearest star. Not taking into account acceleration and deceleration times plus time to explore the target system. Unless there were to be some sort of major, unexpected discovery of a new type propulsion, we can all only dream and take those tiny steps that may someday add up.
Reply | Report Abuse | Link to thishttp://www.tauzero.aero/
When I read that life needs ground and water to form, I always wonder, why can't other forms of life evolve on non-conventional planets? How about vaporous beings? Beings that can live in extremely high temperatures? Beings that breathe carbon dioxide?
Reply | Report Abuse | Link to thisIsn't that possible?
Why do we search for life only on Earth-like planets?
Because we know life can form on Earth-like planets. We don't know if it can form under greatly different circumstances - and although there are suggestions of possible alternative chemistries of sufficient complexity to allow evolving self-replicating entities to form, there is to my knowledge nothing even close to a good case for it, and nobody would know what to look for to discover such life.
Reply | Report Abuse | Link to thisRegarding the cost, the time griffmaster spent typing his short rant, most likely cost him more in lost wages (assuming he could have been working instead) than his tax contribution to the entire Kepler program. In other words, even without any science results, he at least has already got his money's worth. Just lucky for him, Columbus didn't think the other way around was too far, even though that was the consensus at the time. (Of course Columbus was wrong, but so was the assumption that it was just too far for anyone ever to go that way.)
I think that there could be a planet out there that can support life
Reply | Report Abuse | Link to thisThere could be a planet roughly the size of earth around a dwarf star that has the right temperature that can support life. It can also be the right temperature to have water in liquid form. If there is there there could be life even if it is a single cell organism there could be a million more rocky planets out there and we have yet to discover them all.