There is post on a sub I frequent that said there is going to be a [comet](https://www.npr.org/2024/10/10/nx-s1-5148895/how-to-see-comet-c-2023-a3-tsuchinshan-atlas) that won’t be seen for another 80,000 years.
How do we know this particular comet has an 80,000 year long orbit? What are those observations that tell us something like that?
80,000 years ago, as fas as I know, people weren’t writing down astronomical observations. And even if we did, we aren’t relying on their observations today. The post says they discovered this comet in 2023.
What’s our justification for saying something so definitive that this comet won’t be seen for another 80,000 years? I’m not understanding how they would even begin to determine something like that after having discovered it last year.
In: Planetary Science
Lots of great answers so far. We two sufficiently accurate and precise position measurements, we can mostly find the orbit. By using Lambert’s problem, two position measurements and the time between them allows us to solve for two possible orbits. Most of the time you can intuitively select which of the two is accurate or, to be more thorough, a third position measurement would confirm it
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