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At a recent meeting of the American Astronomical Society, Bill Borucki, principal investigator for NASA's planet-finding Kepler spacecraft, provided an update on Kepler's hunt for distant worlds, especially those Earth-like planets that might be habitable:
“We are finding Earth-size planets. Not in the habitable zone. We are looking for planets and finding a few big planets in the habitable zone. Okay, and we are trying to take what we have found and ask, if you see a few how do you extrapolate to the many? When you see a planet by a transit, the orbit has to be in your line of sight. But most orbits won't be. Well, we can correct for that. It's like rolling dice—what are the odds of getting snake eyes? One in 36. So if you get snake eyes there's probably 35 times that you'd roll and you wouldn't get them, for example.
“So we can do the same thing. We can tell in our galaxy there must be billions of planets. Probably on the order of a billion planets in the habitable zone of their stars. That's pretty crude right now—we're refining it—but we're getting the first statistics that are allowing us to make those estimates.”
In next week's episode, Borucki will tell us when Kepler will answer the big question—are habitable, Earth-like planets rare or common?
—John Matson
[The above text is a transcript of this podcast.]
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8 Comments
Add CommentHow common are habitable planets with a single, large, stabilizing moon, or habitable moons with a benevolent, stabilizing planet? Can Kepler address these questions?
Reply | Report Abuse | Link to thisThere was just an article up a bit ago about stablizing moons probably being more common than thought. Do a search and it may well pop up.
Reply | Report Abuse | Link to thisBy the way, you're engaging in a bias. The assumption that just because a moon is thought to be critical to life on this planet doesn't mean it would be on another. Life is pretty damn resourceful. It needn't even be carbon based for that matter.
Reply | Report Abuse | Link to thisThe article you're referring to was based on a simulation of planetary formation. Its results are useful only to the extent that the simulations correctly represented the complex processes of planetary formation.
Reply | Report Abuse | Link to thisI'm more interested in observational evidence, but I don't think that Kepler can reliably identify small planets with even large moons - that's why I ask the simple questions.
Why do you accuse me of bias based on two straightforward questions? You're projecting your own issues onto my simple questions. Researchers have suggested that the moon has been a critical factor in the development of complex life on Earth - the only planet on which we've found evidence of complex life. I assert that stabilizing influences definitely improves any environment's chances of producing complex life. Your remarks do nothing to dissuade me.
You might notice that I also suggest that a planet might provide necessary stabilizing influences for life on some of its moons - an environment that's often not generally considered in discussions of environmental stability.
I suggest that it is you who are engaging in bias against commentators that might suggest that a stable environment is necessary for the development of complex life. Your speculation about non-carbon based life forms are not convincing. We only have evidence for the resiliency of carbon-water based lifeforms.
I suspect that simple life is quite common in the universe and even our own Solar system. Based on available evidence I expect that, intelligent life is most likely to destroy itself after only a few thousand years. Hopefully we'll continue to provide increasing evidence of the sustainability of intelligent life.
@jt, it hasn't been established that moons are a requirement though it seems to be important to you that they are. Regardless, when people point out that moons may be common you dismiss the evidence, "Its results are useful only to the extent that the simulations correctly represented the complex processes of planetary formation". Can the same thing not be said about your personal moon model? I think the task for kepler is difficult enough without you imposing your hypothesis on it. Let's see what we learn from what Kepler finds. Let's not dismiss it just as it is getting started because of our own pet "theories".
Reply | Report Abuse | Link to thisStill cranking out condescending personal critiques of commentators, I see.
Reply | Report Abuse | Link to thisThe suggestion that the moon's stabilizing influence on the Earth greatly enhanced its ability to support the development of complex life was certainly not my idea and can't be dismissed as the "personal moon model" or "pet theory" of some foolish commentator.
Your comments almost sound reasonable, but for your continual reliance on demeaning personal remarks. I will not reply to you again.
Moon formation and spin rate are heavily affected by large late formation collisions. These late collisions are common in a number of simulations.
Reply | Report Abuse | Link to thisA collision that doesn't result in a moon can still end up giving the planet a high spin rate.
High angular momentum either from a collision (moon forming or not) is what stabilises the earth against chaotic obliquity.
Anyway I'd recommend the book "How to Find a Habitable Planet"
The discovery of the first extrasolar planet was announced in 1995 - just 16 years ago. Instead of carping about what Kepler can or can't do, why can't we say "Look how far we've come", and give the mission a chance? How much more will we know in another decade and a half?
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