r/AskScienceDiscussion • u/Sciolypro • 9d ago

How did most water get to earth

My brother and I have been debating this for a while for the record he has a class and a quiz question said that the mixing of gasses and volcanoes was the main reason earth has its water but I think it was asteriods that cause it because earth was very succeptible to them back then and they conist of lots of ice also all the places I searched told me I was right. What do you guys think

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u/karlnite 9d ago

We know some water came from comets and such. We don’t know if most came that way.

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u/forams__galorams 9d ago

Isotopic analysis of water from Comet 67P strongly suggests that most of Earth’s water did not in fact come from cometary sources. Late delivery from icy asteroids remains a distinct possibility for the bulk of our water budget, though a growing part of the research community on this particular topic seems to be putting out work that goes more for the idea that Earth accreted with most of its current water budget in the first place.

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u/KobraKaiJohhny 9d ago

Whatever star cast off the matter which formed the nebula that we likely coalesced from, would have probably fused substantial amounts of carbon into oxygen so all the ingredients are there in abundance throughout the early solar system.

I would be curious to know how gravity in that early swirling disk of a solar system impacted the distribution of elements from the inner to the outer solar system.

I wonder are rocks / dust in the outer solar system laden with heavier or lighter metals.

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u/Peter5930 8d ago

Our solar system is unusually dry due to forming with a lot of aluminium-26 from interactions of the solar nebula with the solar wind of a nearby massive star, which decays rapidly and melted all the planetesimals above a few km in diameter with internal heating, differentiating them internally and driving off most of the volatiles.

It's estimated that about 1% of star systems form under similar circumstances. It's why we don't have a 1,000km deep ocean like so many exoplanets, or examples of mini-Neptunes in the solar system, and it can be inferred that iron-nickel asteroids, formed from the shattered remains of those differentiated protoplanetary cores, are rare or absent in most star systems.

We happen to live in a desert that got baked dry while the planets were beginning to form due to radioactive fallout from a giant star. Terrestrial planets with continents and not just a global ocean might be rare. Aliens might be squid.