Did comets provide Earth's oceans?

[ToSeek]

Rosetta will try to find out (http://www.sciencedaily.com/releases/2004/06/040617081017.htm)


Did the Earth form with water locked into its rocks, which then gradually leaked out over millions of years? Or did the occasional impacting comet provide the Earth's oceans? The Ptolemy experiment on Rosetta may just find out.

The Earth needed a supply of water for its oceans, and the comets are large celestial icebergs - frozen reservoirs of water orbiting the Sun.

Did the impact of a number of comets, thousands of millions of years ago, provide the Earth with its supply of water? Finding hard scientific evidence is surprisingly difficult.

Ptolemy may just provide the information to understand the source of water on Earth. It is a miniature laboratory designed to analyse the precise types of atoms that make up familiar molecules like water.

[George]

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 (http://www.badastronomy.com/phpBB/viewtopic.php?t=13851&highlight=planetary+disk) )?

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

[Brady Yoon]

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?

[eburacum45]

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.

[John Kierein]

Lou Frank
Big Splash
http://www.amazon.com/exec/obidos/tg/detail/-/1559720336/qid=1087648943/sr=1-3/ref=sr_1_3/002-6671098-6588801?v=glance&s=books