Where Did Earth Get Its Oceans? Maybe It Made Them Itself
4 hours ago
- #comets vs asteroids
- #planetary science
- #Earth's water origin
- The traditional theory of Earth's water coming from comets was challenged when spacecraft like Giotto found cometary water had a different chemical signature (D/H ratio) than Earth's.
- Asteroids then became a popular source as their water matches Earth's better, but issues with noble gas compositions and the timing of impacts raise doubts.
- A new hypothesis suggests Earth could have made its own water through a reaction between hydrogen in the early atmosphere and oxygen in a magma ocean under high pressure.
- Lab experiments mimicking conditions on exoplanets (sub-Neptunes) show that such reactions can produce vast amounts of water, possibly applicable to Earth.
- Recent studies suggest comets might still have contributed, as some like Hartley 2 and 12P/Pons-Brooks have Earth-like D/H ratios, complicating the origin story.
- The origin of Earth's water likely involves a combination of internal processes and extraterrestrial sources, with ongoing research enriching the scientific narrative.