Former gas giants, climate on Titan, and the rarity of our solar system

Tuesday, January 12, 2010

Here are three links from the past few days that are worth sharing:

First this one on the climate on Titan, which is turning out to be more and more Earth-like the more we find out about it. A recent photo of Titan also showed light glinting off the lakes on the surface, confirming once and for all the presence of liquid on the surface. Perhaps the surface of one of these lakes might look like this.

You might also remember an article about a star that could wipe out the Earth by going supernova in the next few hundred million turns out that isn't true, and that the calculations were done on the assumption that it would be a gamma burst, not a supernova. Oops.

This one is interesting too - apparently the most Earth-like planet we've discovered so far began as a gas giant, but has shrunk since then and is continuing to do so.

Finally, this one - as we discover more and more extrasolar planets and learn more about other solar systems we are beginning to reach a point where we can begin to make the first tentative conclusions about what types of solar systems are common and which aren't, and apparently our type of solar system should be found in about 15% of the solar systems in the Milky Way. That's actually a bit higher than I had expected. Nevertheless, since red dwarfs are the most common stars out there it's possible that any intelligent life on a planet around a red dwarf would assume that life couldn't exist on larger stars in the same way we assume that blue giants are bad candidates for life. Their assumption might be that a planet around a yellow giant (as our star would be called) would have to be so far away from its parent star to be in the habitable zone that it wouldn't be tidally locked, and thus would flip about so randomly (in the long term) that it would undergo cycles of heat and cold (i.e. seasons) that would make it impossible for life to exist. In comparison, a planet around a red dwarf with a thick enough atmosphere would be tidally locked and wouldn't have seasons, and the band around the middle of the planet where the sun is always close to the horizon but never sets would always be at a perfect temperature. The part facing the star would likely be too hot to support life, but then again Earth has Antarctica, a place where pretty much no life exists either, so having a few inhabitable locations on a planet certainly doesn't exclude the rest of it from maintaining life.


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