Nice narrative on BBC about the origins of Earth’s oceans. For me, I’d rather see a little more evidence on the premise. Science has waffled back and forth on this point for awhile. But I think “alien” origins of water are likely.
It’s interesting, that use of the term “alien.” By the standard of the article author, Earth was formed by the conglomeration of bodies alien to one another. If we’re all sharing one happy solar system, maybe we’re not so alien to one another–meaning Venus, Earth, Mars, and other planets. We can say “extra-terrestrial,” or “beyond Earth” with more accuracy.
When I think of “alien” I think of other star systems. Something totally out there. And I don’t think of other continents or even other countries. Immigrants are just that, regardless of their legal status: not alien, but just travelers, pilgrims, and movers. Not at all alien. Western culture would be better off comet-impacting that thought out of its head. We become collectives as we human beings gather and conglomerate. Sisters and brothers once sundered, now together, and largely for the better.
Image: Comet ISON from Hubble Space Telescope.