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Space Science

Asteroid Crashes Likely Gave Earth Its Water 138

Posted by samzenpus
from the space-water dept.
Diggester writes "Asteroids from the inner solar system are the most likely source of the majority of Earth's water, a new study suggests. The results contradict prevailing theories, which hold that most of our planet's water originated in the outer solar system and was delivered by comets or asteroids that coalesced beyond Jupiter's orbit, then migrated inward."
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Asteroid Crashes Likely Gave Earth Its Water

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  • by Tukz (664339) on Sunday July 15, 2012 @12:39PM (#40656743) Journal

    Frozen rocks basically, but yes.
    They slammed into earth.

    Watch some Discovery or read some books some times.
    This is nothing new.

    What may be new, is the fact that these asteroids may be from further away than first anticipated.

  • by MightyYar (622222) on Sunday July 15, 2012 @01:01PM (#40656889)

    It looks like a lot of water, but it's mostly on the surface so it is misleading. Here's a neat graphic. [abovetopsecret.com]

  • by amck (34780) on Sunday July 15, 2012 @01:30PM (#40657037) Homepage

    Some people call it gravity.

    Note: Earth has about 0.1 - 0.01 % water by mass (depending on how much water you think there is in the mantle). Compared to the outer solar system (typically 50%) it's not _that_ massive.

  • Yes, it would (Score:5, Informative)

    by F69631 (2421974) on Sunday July 15, 2012 @03:11PM (#40657727)

    According to quick Google, average depth of oceans is about 4km, surface area of earth is about 510'072'000 km2 and water covers about 70% of earths surface.

    5.1E8 km2 * 4km * 0.7 = 1.428 billion km3. Sphere of that volume is about 1396 km across.

    The GP's graph says "1390 kilometres across and has a volume of 1.4 billion cubic kilometres", which is very close to that quick approximation.

    My approximation is very quick and dirty (I didn't take into account that surface of earth is less 4km below the surface than on the surface, which would reduce the sphere... but I also didn't take into account glaciers, etc. which would increase the sphere... Obviously the surface of sea isn't exactly 70% and the depth isn't exactly 4km...) but I feel very confident that the scale of the number is about right and it happens to perfectly match the graph.

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