How do we know this comet, C 2023 a3, was last above earth 80,000 years ago?

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https://metro.co.uk/2024/09/29/see-a-once-80-000-years-comet-uk-october-2024-21699657/

I’ve seen a few posts and articles about this comet and how the last time it was this close to earth was about 80,000 years ago. I think that’s super cool but I don’t understand how we would know that.

In: Planetary Science

4 Answers

Anonymous 0 Comments

We can calculate orbits very precisely. The physics and math to do it is well established and thoroughly validated.

We can make observations of far dimmer objects very precisely. Comets are by their nature very easy to track.

So we can figure out the orbit of a comet, and how long it takes it to make a round trip, fairly easily.

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