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I thought the Oort cloud is a (sound) hypothesis, not a confirmed thing? > [long-period comets] originate in the Oort cloud, which extends several light-years
by rich_sasha 6y ago
I thought the Oort cloud is a (sound) hypothesis, not a confirmed thing?
> [long-period comets] originate in the Oort cloud, which extends several light-years from the sun [...] to the edge of the solar system
- simonh 6y agoYes that's correct, it's not possible to directly observe these objects at the moment.
- marcus_holmes 6y agoI also thought the cloud wasn't that big. 200,000 AUs is 3 and a bit LY. Alpha Centauri is 4 and a bit LY away. When does our cloud stop and theirs begin?
- antognini 6y agoThe extent of the Oort cloud is basically defined by the point where Galactic tides start to overwhelm the gravitational attraction to the Sun. But objects in the outer Oort cloud are very loosely bound and can easily be expelled or exchanged by interactions from passing stars.
- simonh 6y agoI suppose Alpha Centauri is only in one specific direction, so it distorts the cloud in that region.
- rich_sasha 6y agoThere’s also other “clouds”, with smaller radii. Kuiper Belt is roughly where Pluto is. There is the Scattered Disc (probably) beyond that. Only then, a long way away, maybe, the Oort Cloud. So there is a lot of cloudy stuff closer in too.