Comment by ceejayoz
2 days ago
How do we know they're anomalous characteristics if it's literally the first one we've ever spotted? What is the normal shape of an interstellar comet core?
2 days ago
How do we know they're anomalous characteristics if it's literally the first one we've ever spotted? What is the normal shape of an interstellar comet core?
The same as the ones from this system. Borisov had the same characteristics.
> The same as the ones from this system.
Why would we assume non-interstellar comets are always the same as interstellar comets? Conditions obviously are a little different when something is ejected from a system and then spends millions of years in interstellar space.
> Borisov had the same characteristics.
We have a sample size of three thus far. Making conclusions right now is like saying all extrasolar planets are large gas giants because the first three were.
We'd assume most interstellar objects are comets because that's which objects you find on the outskirts of a solar system and are the easiest to get kicked out. We'd assume they're mostly like our comets due to the Copernican principle. We shouldn't assume we're special.
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For example, being flat like a pancake is obviously highly unusual and very different from anything we have seen from stellar comets.
Stellar comets haven't been ejected from another solar system. We have vanishingly few examples of those, and we've not directly observed any up close.
"Flat as a pancake" is one of several theoretical possibilities from its light curve, not a known fact about the object.
"Highly unusual" in space tends to mean "there are a bunch, but we haven't seen them until now". In 1992, exoplanets were "highly unusual". Now they're everywhere.
Yes, and the exoplanets we found first were highly unusual and not at all what we expected to find, which triggered tons of new research to amend our models of planetary system formation and dynamics. I’m not even sure what you’re trying to argue here – we found an object that did not fit our model of what things should look like, which is very curious and calls for an explanation. That’s how science works. Doesn’t mean it’s aliens. But “oh well maybe it’s just how things are back where it’s from” does not satisfy anyone.
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The highly unusual properties are such that they are genuinely hard to explain for astronomers. See my neighbouring comment.