Science Questions

Nassar asked the Naked Scientists: I know that the water on Earth came from comets colliding into the Earth in its early history. But, where did the comets get the water from. Thanks... love the show. Nassar What do you think?

All the elements higher than lithium were formed and distributed through galaxies by supernova explosions initially they were just atomic nuclei but as they cooled the gradually gathered electrons (the electrons were always around because it stars are a neutral plasma)and became neutral atoms.  As the cooling process progressed  these atoms could form chemical compounds and as there was always lots of hydrogen around water and other hydrides are the more common compounds to be found as the gas cools down a lot these molecules tend to stick together to form interstellar granules which eventually get big enough to be comets.

I suppose the polar nature of water, which allows it to make hydrogen bonds, also favours the aggregation of water molecules to form larger accumulations?

Chris

Very probably the presence of water on the surface of small particle will probably help them to stick together when the gravitiational attraction is too low to hold them together.

Thanks Chris and Soul Surfer; these responses make sense. I was not too pleased with the response from the Astronomer in the podcast though.

I, too, had this question on the origin of water in comets and this thread has been useful. Thanks.

And I agree with @lunar11. The podcast (at about 49:30) did not answer the question: "It's just left-over stuff"!!! :/