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
You can calculate the orbit of an astronomical object without having to see its entire orbit. We ‘discover’ comets and asteroids by making observations of them, mathematically predicting where they should go, and then following up later to see if they’re actually there. If they are, we know the orbit with a degree of certainty that increases with each subsequent observation. And once you know the orbit, you know how long it will be before it returns to the area it will be observable from Earth.
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