APOD: Introducing Comet Nishimura (2023 Aug 21)

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APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by APOD Robot » Mon Aug 21, 2023 4:09 am

Image Introducing Comet Nishimura

Explanation: Will Comet Nishimura become visible to the unaided eye? Given the unpredictability of comets, no one can say for sure, but it currently seems like a good bet. The comet was discovered only ten days ago by Hideo Nishimura during 30-second exposures with a standard digital camera. Since then, C/2023 P1 Nishimura has increased in brightness and its path across the inner Solar System determined. As the comet dives toward the Sun, it will surely continue to intensify and possibly become a naked-eye object in early September. A problem is that the comet will also be angularly near the Sun, so it will only be possible to see it near sunset or sunrise. The comet will get so close to the Sun -- inside the orbit of planet Mercury -- that its nucleus may break up. Pictured, Comet Nishimura was imaged three days ago from June Lake, California, USA while sporting a green coma and a thin tail.

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by Joe Stieber » Mon Aug 21, 2023 5:03 am

On Saturday morning, 19-August-2023, I saw C/2023 P1 (Nishimura) visually from the New Jersey Pinelands with my 115 mm spotting scope, around the start of astronomical twilight. Of course, to the eye it was just a grayish haze, unlike the lush color of today's APOD, and there was no tail visually. In any case, it's currently an accessible object with modest optics... if you get up early in the morning.

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by Rauf » Mon Aug 21, 2023 8:04 am

Who will have a better chance for seeing this comet, northern hemisphere observers or southern?

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by johnnydeep » Mon Aug 21, 2023 1:24 pm

Rauf wrote: Mon Aug 21, 2023 8:04 am Who will have a better chance for seeing this comet, northern hemisphere observers or southern?
I think Northern, but maybe Southern observers could still view it at some points in its journey, based on what's stated at https://starwalk.space/en/news/new-comet-c2023-p1, but I've yet to find a definitive statement about the best locations for seeing it.

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by Rauf » Mon Aug 21, 2023 1:59 pm

johnnydeep wrote: Mon Aug 21, 2023 1:24 pm
Rauf wrote: Mon Aug 21, 2023 8:04 am Who will have a better chance for seeing this comet, northern hemisphere observers or southern?
I think Northern, but maybe Southern observers could still view it at some points in its journey, based on what's stated at https://starwalk.space/en/news/new-comet-c2023-p1, but I've yet to find a definitive statement about the best locations for seeing it.

Seems like it'll be too close to the sun when it is at it's brightest. It'll be tough to observe. Let's hope it doesn't break up before giving us a good show!

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by smitty » Mon Aug 21, 2023 2:16 pm

Question: Is anyone else surprised that comets are still being discovered by individual astronomers such as in this case? It seems that automated searches are still not fool-proof. https://www.nasa.gov/nasa-soho-comet-search .

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by orin stepanek » Mon Aug 21, 2023 3:48 pm

comet-and-person-howen-unsplash.jpg
Comet watching! I Hope it does become visible to the naked Eye!
Seems there is some doubt in the writeup! :?
61MnQVQct8L._AC_UF894,1000_QL80_.jpg
Doggy shading his eyes! :D
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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by johnnydeep » Mon Aug 21, 2023 5:32 pm

I kind of like the unpredictability of discovering new comets, but that also means the Earth could become an impact site for one some day. I only hope we get enough warning beforehand to at least try to do something about it, though it seems doubtful we would be successful.
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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by Rauf » Mon Aug 21, 2023 6:41 pm

johnnydeep wrote: Mon Aug 21, 2023 5:32 pm I kind of like the unpredictability of discovering new comets, but that also means the Earth could become an impact site for one some day. I only hope we get enough warning beforehand to at least try to do something about it, though it seems doubtful we would be successful.
Isn't discovering potentially hazardous comets easier than discovering PHAs? Comets tend to brighten as they get close to the sun, and that helps us find them easier. You can't say the same for asteroids though.

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by johnnydeep » Mon Aug 21, 2023 7:00 pm

Rauf wrote: Mon Aug 21, 2023 6:41 pm
johnnydeep wrote: Mon Aug 21, 2023 5:32 pm I kind of like the unpredictability of discovering new comets, but that also means the Earth could become an impact site for one some day. I only hope we get enough warning beforehand to at least try to do something about it, though it seems doubtful we would be successful.
Isn't discovering potentially hazardous comets easier than discovering PHAs? Comets tend to brighten as they get close to the sun, and that helps us find them easier. You can't say the same for asteroids though.
True, but this particular comet wasn't caught until pretty close to us, and we would only have had a few months to prepare (to die!) if it was on a collision course. Also, my understanding is that comets can come from just about any orbital inclination, since many(most?) originate in the spherical Oort cloud, whereas asteroids usually originate in the Kuiper belt and so have orbital inclinations similar to Earth's. (Someone please correct me if I'm mistaken.)
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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by Chris Peterson » Mon Aug 21, 2023 7:36 pm

Rauf wrote: Mon Aug 21, 2023 6:41 pm
johnnydeep wrote: Mon Aug 21, 2023 5:32 pm I kind of like the unpredictability of discovering new comets, but that also means the Earth could become an impact site for one some day. I only hope we get enough warning beforehand to at least try to do something about it, though it seems doubtful we would be successful.
Isn't discovering potentially hazardous comets easier than discovering PHAs? Comets tend to brighten as they get close to the sun, and that helps us find them easier. You can't say the same for asteroids though.
No. PHAs are almost universally in inner system orbits that are Earth-crossing or near Earth-crossing. They don't just show up from the outer system. Many comets, however, are first time visitors, and depending on where they come from, can't easily be seen against the Sun until they're too close to potentially do anything about them. Also, he search zone for comets is much larger (because asteroids are mostly fairly low inclination, whereas comets can come from any direction).

Reliable detection of comets really requires a space-based observation system. That's much less an issue with asteroids.
Chris

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by Rauf » Mon Aug 21, 2023 7:41 pm

Chris Peterson wrote: Mon Aug 21, 2023 7:36 pm
Rauf wrote: Mon Aug 21, 2023 6:41 pm
johnnydeep wrote: Mon Aug 21, 2023 5:32 pm I kind of like the unpredictability of discovering new comets, but that also means the Earth could become an impact site for one some day. I only hope we get enough warning beforehand to at least try to do something about it, though it seems doubtful we would be successful.
Isn't discovering potentially hazardous comets easier than discovering PHAs? Comets tend to brighten as they get close to the sun, and that helps us find them easier. You can't say the same for asteroids though.
No. PHAs are almost universally in inner system orbits that are Earth-crossing or near Earth-crossing. They don't just show up from the outer system. Many comets, however, are first time visitors, and depending on where they come from, can't easily be seen against the Sun until they're too close to potentially do anything about them. Also, he search zone for comets is much larger (because asteroids are mostly fairly low inclination, whereas comets can come from any direction).

Reliable detection of comets really requires a space-based observation system. That's much less an issue with asteroids.
True, most PHAs we've discovered are in inner solar system. But what about small sized TNOs with similar orbits as comets, but much harder to detect?
Asteroids from outer solar system might be common (with high eccentricities that'll get them close to the sun at some point in their orbit) , but since we don't see them that often, we might not discover them at all (because unlike comets, they don't get bright)
If however, I am mistaken, please tell me why. :ssmile:

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by Chris Peterson » Mon Aug 21, 2023 7:58 pm

Rauf wrote: Mon Aug 21, 2023 7:41 pm
Chris Peterson wrote: Mon Aug 21, 2023 7:36 pm
Rauf wrote: Mon Aug 21, 2023 6:41 pm

Isn't discovering potentially hazardous comets easier than discovering PHAs? Comets tend to brighten as they get close to the sun, and that helps us find them easier. You can't say the same for asteroids though.
No. PHAs are almost universally in inner system orbits that are Earth-crossing or near Earth-crossing. They don't just show up from the outer system. Many comets, however, are first time visitors, and depending on where they come from, can't easily be seen against the Sun until they're too close to potentially do anything about them. Also, he search zone for comets is much larger (because asteroids are mostly fairly low inclination, whereas comets can come from any direction).

Reliable detection of comets really requires a space-based observation system. That's much less an issue with asteroids.
True, most PHAs we've discovered are in inner solar system. But what about small sized TNOs with similar orbits as comets, but much harder to detect?
Asteroids from outer solar system might be common (with high eccentricities that'll get them close to the sun at some point in their orbit) , but since we don't see them that often, we might not discover them at all (because unlike comets, they don't get bright)
If however, I am mistaken, please tell me why. :ssmile:
There is really nothing to suggest that there are very many outer system stony bodies. Or many bodies in Earth-crossing orbits that take them way out there. Basically, there are two populations of objects that we need to concern ourselves with. Asteroids, which are inner system bodies in small orbits, and comets, which are outer system bodies in very large orbits. (There is, of course, a small population of comets which have become much more asteroidal in their orbits, but we can treat them just as we do asteroids when it comes to identifying those that have the potential to impact the Earth.)

We can detect and catalog the vast majority of inner system bodies and then mostly forget about them, just checking a few from time to time because they could be perturbed into dangerous orbits. The challenge is comets, where we can never stop searching, and we can't effectively do so from Earth because of the Sun getting in the way of a big chunk of sky.
Chris

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by johnnydeep » Mon Aug 21, 2023 8:49 pm

Chris Peterson wrote: Mon Aug 21, 2023 7:58 pm
Rauf wrote: Mon Aug 21, 2023 7:41 pm
Chris Peterson wrote: Mon Aug 21, 2023 7:36 pm
No. PHAs are almost universally in inner system orbits that are Earth-crossing or near Earth-crossing. They don't just show up from the outer system. Many comets, however, are first time visitors, and depending on where they come from, can't easily be seen against the Sun until they're too close to potentially do anything about them. Also, he search zone for comets is much larger (because asteroids are mostly fairly low inclination, whereas comets can come from any direction).

Reliable detection of comets really requires a space-based observation system. That's much less an issue with asteroids.
True, most PHAs we've discovered are in inner solar system. But what about small sized TNOs with similar orbits as comets, but much harder to detect?
Asteroids from outer solar system might be common (with high eccentricities that'll get them close to the sun at some point in their orbit) , but since we don't see them that often, we might not discover them at all (because unlike comets, they don't get bright)
If however, I am mistaken, please tell me why. :ssmile:
There is really nothing to suggest that there are very many outer system stony bodies. Or many bodies in Earth-crossing orbits that take them way out there. Basically, there are two populations of objects that we need to concern ourselves with. Asteroids, which are inner system bodies in small orbits, and comets, which are outer system bodies in very large orbits. (There is, of course, a small population of comets which have become much more asteroidal in their orbits, but we can treat them just as we do asteroids when it comes to identifying those that have the potential to impact the Earth.)

We can detect and catalog the vast majority of inner system bodies and then mostly forget about them, just checking a few from time to time because they could be perturbed into dangerous orbits. The challenge is comets, where we can never stop searching, and we can't effectively do so from Earth because of the Sun getting in the way of a big chunk of sky.
So, I suppose comets can come from both the Kuiper belt and the Oort cloud, but asteroids come from within the orbit of Jupiter? Do asteroids ever originate in the Kuiper belt?

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by Chris Peterson » Mon Aug 21, 2023 9:05 pm

johnnydeep wrote: Mon Aug 21, 2023 8:49 pm
Chris Peterson wrote: Mon Aug 21, 2023 7:58 pm
Rauf wrote: Mon Aug 21, 2023 7:41 pm

True, most PHAs we've discovered are in inner solar system. But what about small sized TNOs with similar orbits as comets, but much harder to detect?
Asteroids from outer solar system might be common (with high eccentricities that'll get them close to the sun at some point in their orbit) , but since we don't see them that often, we might not discover them at all (because unlike comets, they don't get bright)
If however, I am mistaken, please tell me why. :ssmile:
There is really nothing to suggest that there are very many outer system stony bodies. Or many bodies in Earth-crossing orbits that take them way out there. Basically, there are two populations of objects that we need to concern ourselves with. Asteroids, which are inner system bodies in small orbits, and comets, which are outer system bodies in very large orbits. (There is, of course, a small population of comets which have become much more asteroidal in their orbits, but we can treat them just as we do asteroids when it comes to identifying those that have the potential to impact the Earth.)

We can detect and catalog the vast majority of inner system bodies and then mostly forget about them, just checking a few from time to time because they could be perturbed into dangerous orbits. The challenge is comets, where we can never stop searching, and we can't effectively do so from Earth because of the Sun getting in the way of a big chunk of sky.
So, I suppose comets can come from both the Kuiper belt and the Oort cloud, but asteroids come from within the orbit of Jupiter? Do asteroids ever originate in the Kuiper belt?

"Asteroid" is generally understood to be an inner system body that formed there, while outer system bodies are typically much less rocky, composed mainly of ice, and formed by different processes.

Whether the body is made of rock or ice really doesn't matter that much beyond a certain size. You don't want either to hit us! So rather than worrying about "comets" or "asteroids", I think the way I framed it earlier makes the most sense: two populations, one of which is in pretty stable (but perturbable) orbits in the inner system and which can be cataloged, with potential problems observed more closely, and bodies that we do not know about until they get close enough to be seen the first time. The odds of an asteroid catching us by surprise are small, and getting smaller all the time as we catalog more of them, and smaller ones. Surprises will come from the outer system, likely from first time visitors that we know nothing about.
Chris

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Re: APOD: Introducing Comet Nishimura (2023 Aug 21)

Post by johnnydeep » Tue Aug 22, 2023 1:57 pm

Chris Peterson wrote: Mon Aug 21, 2023 9:05 pm
johnnydeep wrote: Mon Aug 21, 2023 8:49 pm
Chris Peterson wrote: Mon Aug 21, 2023 7:58 pm

There is really nothing to suggest that there are very many outer system stony bodies. Or many bodies in Earth-crossing orbits that take them way out there. Basically, there are two populations of objects that we need to concern ourselves with. Asteroids, which are inner system bodies in small orbits, and comets, which are outer system bodies in very large orbits. (There is, of course, a small population of comets which have become much more asteroidal in their orbits, but we can treat them just as we do asteroids when it comes to identifying those that have the potential to impact the Earth.)

We can detect and catalog the vast majority of inner system bodies and then mostly forget about them, just checking a few from time to time because they could be perturbed into dangerous orbits. The challenge is comets, where we can never stop searching, and we can't effectively do so from Earth because of the Sun getting in the way of a big chunk of sky.
So, I suppose comets can come from both the Kuiper belt and the Oort cloud, but asteroids come from within the orbit of Jupiter? Do asteroids ever originate in the Kuiper belt?

"Asteroid" is generally understood to be an inner system body that formed there, while outer system bodies are typically much less rocky, composed mainly of ice, and formed by different processes.

Whether the body is made of rock or ice really doesn't matter that much beyond a certain size. You don't want either to hit us! So rather than worrying about "comets" or "asteroids", I think the way I framed it earlier makes the most sense: two populations, one of which is in pretty stable (but perturbable) orbits in the inner system and which can be cataloged, with potential problems observed more closely, and bodies that we do not know about until they get close enough to be seen the first time. The odds of an asteroid catching us by surprise are small, and getting smaller all the time as we catalog more of them, and smaller ones. Surprises will come from the outer system, likely from first time visitors that we know nothing about.
Ok. So as for the initial make-up of almost all the objects in both the Kuiper belt and the Oort cloud, is it correct to say that almost all of them are "dirty snowballs" and almost none would lack ice? (Though, granted, as you've said, over time comets can become depleted of ice over successive trips to the inner solar system.)
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