Literally, look who's back: A comet that last swung by Earth 50,000 years ago Get a look while you can: a comet that last graced Earth's sky tens of thousands of years ago is back, and may now be visible to the naked eye – or at least those with binoculars – later this month and into February. And not only has C/2022 E3 (ZTF) been away for quite some time, it may never come this way again, astronomers …
I skipped the check for where in the sky to look and went directly to the long range rain forecast. My expectations were sufficiently low that I was not disappointed.
Apologies, 'tis all my fault.
I had a new telescope for Christmas. Consequently January is a washout...
This is an interesting case (and one I'd not noticed until reading this article; my "day job" is computing orbits for asteroids, with comets a distant second). It'll pick up just enough energy coming through the solar system to put it in a nearly-but-not-quite escape orbit by the time it leaves. Nominally, if there were no nearby stars, it would get about 9 +/- 3 light-years out, then come back... after about 200 million years.
Since there _are_ nearby stars, it's more likely to get picked off from us by the neighbors and go into interstellar space. A few billion years from now, it could eventually be some alien's version of `Oumuamua or 2I/Borisov (the two interstellar wanderers we've seen going through our solar system; Borisov, at least, looks to be a comet that some other star system threw out).
We've seen a few similar cases before of comets getting tossed out of the solar system. It's a little unusual, but not surprising.
Should note that even though we have a lot of measurements of this object, I still have to say "unlikely" rather that "certain" not to come back. First, it's really right at the edge of being parabolic. Second, comets sometimes have (unpredictable) tiny trajectory changes due to eruptions from their surfaces. Not likely to matter much here, since it's big and not coming very close to the sun, but Stuff Does Happen with comets, and again, it wouldn't take much of a change near perihelion to have an outsized effect on where it eventually ends up. Somebody once wrote that comets are like cats : they both have tails and they do what they want.
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