Rosetta will try to find out

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Everything I need to know I learned through Googling.

In light of the proto-planetary disk found within a stellar accretion disk (Spitzer last month, I think), wouldn't water be more likely from the disk itself?

BTW, have you seen anything more regarding that announcement you posted ( post )?

Isn't aggregation the prevailing theory on planet formation, or is it? Or was it?

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Lighten up! This is a stellar board!

I think it still is. By the way, does the amount of water on Earth surface and atmosphere remain constant? Water is brought to Earth by outgassing and small comets (perhaps) and lost by photodissociation by UV radiation. Are these two processes equal right now?

Complicating matters is the possible 'Big Splash' impact which formed the Moon;

as you might expect, the big splash (if it occurred) will have caused any oceans on the surface of the Earth to be ejected into space; much of the water may have fallen back onto the Earth, but our planet will have permanently lost quite a large fraction of the primeval H20.

So a large proportion of the water on Earth now must have come later, presumably from comets.
If this impact had not occured the Earth might have been covered in water by now, as those comets will have hit Earth anyway in all probability; we would have been a waterworld.

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New Orion's Arm Site . The Starlark . Against a Diamond Sky (OA Novella Collection) . OA Flickr set

Lou Frank
Big Splash
http://www.amazon.com/exec/obidos/tg...ce&s=books