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WillingnessOk3081 t1_j1zrgtr wrote

very simple question from somebody who knows nothing, but how does water survive the enormously high temperatures of entry in the atmosphere to the earth’s crust?

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RipleyKY t1_j1zz8w2 wrote

There wasn’t much of an atmosphere to begin with. We wouldn’t even have much of an atmosphere without water vapor. Early Earth would have been essentially a ball of molten rock/lava.

Over billions of years, Earth was impacted by asteroids (and is theorized that Earth had an impact with another proto-planet that formed our moon). Those asteroids deposited key elements (hydrogen, helium, oxygen, ie water) and its impact trapped them deep into Earths mantle.

Over time the planet experienced fewer outer body impacts and cooled to form our crust. Yet, volcanic activity allowed for those elements previously trapped to release in the forms of carbon dioxide, ammonia, and water vapor. The release of these key elements subsequently formed our atmosphere, and allowed our oceans to form as well.

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WillingnessOk3081 t1_j200sim wrote

this is a very helpful explanation. thank you! also very cool to think about.

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citro-naut t1_j2262kn wrote

Yes. We measure water in meteorites that have survived atmospheric entry. A tremendous amount of mass (including water) is lost (vaporized) during entry but most of it should be retained in the atmosphere.

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