Comet C/2023 a3

[WLJ]

I figure disunirregardless of the low temperatures involved, in 80,000 years it will have evaporated down to a loose assortment of rocks and dust loosely held together only by their own small mutual gravity.

Once it leaves the inner solar system it will freeze right back up and will remain so for those 80k years. If it returns in 80k years it will be just like the the day it left. One reason comets are so interesting to scientists as many are left over from the formation of the Sol system and many have remained in a far obit since then until something, a passing star or planet, etc... knocked them out of their stable obit sending them into the inner solar system.

[K Frame]

From what I've read, comets lose virtually none of their mass when they escape the effects of the star that they orbit.

It's simply back to a deep freeze. I would assume that sublimation would still happen (especially given that there's no atmospheric pressure to work against sublimation) but I'm not sure how that process would be affected by deep space's average -454 F temperature.

[230RN]

"I figure disunirregardless of the low temperatures involved, in 80,000 years it will have evaporated down to a loose assortment of rocks and dust loosely held together only by their own small mutual gravity"

"Virtually zero" loss is not zero loss.

"..average -454 F temperature" is not zero temperature.  Remember, temperature is a measurement of the velocity of impacting particles being transferred to the thermometer or object.

There are particles running around loose in "space."  Some are bound to impinge on your temperature measuring device, and some are bound to impinge on the comet --imparting velocity to the molecules of the comet or your measuring device.  This may be too small an amount to observe, but it's there nonetheless.

Remember the definition of "absolute zero."

Some of those impinging particles may "stick" because of the  comet's own gravity, thus tending to increase its mass again, but my bet is the overall effect of the temperature/velocity of the impact will outweigh this effect.  Besides maybe knocking off a couple of other particles to boot.

Your (plural you) assertions are commonly held and sort of pretend the comet will be "lonely."
 
My assertion is basically theoretical but not commonly held and presumes the comet will not be "lonely."

That's the way I figured it, per quote.

Call me in 80,000 years and let me know whose assertions took precedence in this long-term empirical test of alternatives.  My phone number then will be (303) 874²⁰-939i67399478.  Leave a messaage.



Terry, 230RN

[K Frame]

""Virtually zero" loss is not zero loss."

Did I say it was?

"average -454 F temperature" is not zero temperature."

Did I say it was?

"There are particles running around loose in "space."

Yes there are. In deep space, there are only, on average, something like 3 hydrogen atoms per cubic meter. In interplanetary space (inside a solar system like ours) that number goes up to thousands per cubic centimeter. Vastly more.

So yeah, while there's still matter in deep space, its "pressure effect" on any object is close enough to nonexistent to be largely discounted.


So, what we're down to is as I said, comets lose virtually none (please read that two-word phrase as many times as you need to understand that in no way did I say OR claim that virtually none somehow equals none) of their mass while in the deep space phase of their orbit. If you don't like the phrase virtually none, we can go with "so little as to be negligible" or something similar.

In effect, it would appear that once comets reach their deep space orbit, they become nearly dormant (again, read that two word phase carefully and note that nearly dormant is NOT equal to dormant) in their material loss.

The fact that Halley's comet has been trapped in its orbit to our solar system for upwards 200,000 years means that comets (at least some) do, apparently have far more staying power than you think given that at least this one (and possibly other observable comets) have survived multiple orbits into and out of our solar system.

That said, are comets "eternal"? Comet Shoemaker Levy very nicely answers that question.

[Ben]

Well, at least with my photog skills (or lack thereof) the comet is already too far away. Last night, even with the big telephoto, it was dim enough that exposure just made it an unfocused blob. You can still see it with binos, but it's definitely not as spectacular as it was even just a few nights ago.

It was still cool to see, and I got some images and video that I'm happy with. I don't know how many comets I have left at my age. 

[K Frame]

I never did see it. The moon, combined with the background light pollution, and the fact that it was pretty low on the horizon meant that I would have had to have found spot with an unobstructed view, and those can be kind of hard to find in this area.

[Ben]

I never did see it. The moon, combined with the background light pollution, and the fact that it was pretty low on the horizon meant that I would have had to have found spot with an unobstructed view, and those can be kind of hard to find in this area.

It's actually pretty high in the sky right now, though as you mention, light pollution will be an issue, especially with how far away it is now. The bummer was that when it was close, even outside of light pollution, the stupid moon was high and bright. I think tonight will be the first night that the comet will be out but the moon won't, at least for an hour or so. I think it would have been spectacular to see it five days ago without a visible moon.

Also for me, even though I'm in a pretty dark area, I got screwed because the comet was in the West, and there's a dairy operation about a mile West of me. You wouldn't believe the lights those guys have on all night. It's a very noticeable difference to look at astronomical stuff lower on the horizon in the West and East for me.

[230RN]

"That said, are comets "eternal"? Comet Shoemaker Levy very nicely answers that question."

Thank you.

And analysis of "virtually zero" will reveal the stunning notion that the subject phenomenon is not zero, null, nada, nichevo, nothing.

A temperature of minus 454 degrees is not -459.7F (absolute zero) which implies there is some heat in the body, hence some molecular motion.

What was said about our little comet implies perpetuality and depends on different presumptions than mine. Once again, they presume absolute "loneliness" of the comet throughout its journey. 

I say many factors will affect it --it will not be "lonely" and might in fact exist only as a loose mutually attracted collection of rocks and dust after 80,000 years. As I said.

I've got ten bucks down on my "theory,'" which challenges "quick and dirty" offhand presumptions.  Am I covered?

See my phone number above.

Terry, 230RN