APOD: Expanding Plume from DART's Impact (2022 Oct 05)

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APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by APOD Robot » Wed Oct 05, 2022 4:05 am

Image Expanding Plume from DART's Impact

Explanation: What happens if you crash a spaceship into an asteroid? In the case of NASA's DART spaceship and the small asteroid Dimorphos, as happened last week, you get quite a plume. The goal of the planned impact was planetary protection -- to show that the path of an asteroid can be slightly altered, so that, if done right, a big space rock will miss the Earth. The high brightness of the plume, though, was unexpected by many, and what it means remains a topic of research. One possibility is that 170-meter wide Dimorphos is primarily a rubble pile asteroid and the collision dispersed some of the rubble in the pile. The featured time-lapse video covers about 20 minutes and was taken from the Les Makes Observatory on France's Reunion Island, off the southeast coast of southern Africa. One of many Earth-based observatories following the impact, the initial dot is primarily Dimorphos's larger companion: asteroid Didymos. Most recently, images show that the Didymos - Dimorphos system has developed comet-like tails.

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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by Cousin Ricky » Wed Oct 05, 2022 5:48 am

What’s up with this? The video as posted is too large to fit on my screen, so I chose Watch on YouTube, but all I get are right wing propaganda shorts.

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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by AVAO » Wed Oct 05, 2022 7:19 am

Cousin Ricky wrote: Wed Oct 05, 2022 5:48 am What’s up with this? The video as posted is too large to fit on my screen, so I chose Watch on YouTube, but all I get are right wing propaganda shorts.
That's right! Please correct...

Original source of the video:
https://www.esa.int/ESA_Multimedia/Vide ... the_ground

APOD video source on youtube:
https://www.youtube.com/watch?v=MC8f6gxqn3s

76AD

Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by 76AD » Wed Oct 05, 2022 12:16 pm

Cousin Ricky wrote: Wed Oct 05, 2022 5:48 am What’s up with this? The video as posted is too large to fit on my screen, so I chose Watch on YouTube, but all I get are right wing propaganda shorts.
I watched on youtube & the video was a boxing match, a guy with a mullet KO's a steroid infused guy with a white power tattoo. That's not right wing propaganda :lol2:

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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by orin stepanek » Wed Oct 05, 2022 12:32 pm

310719168_5102042639899914_7436403042388177876_n.jpg
From dust to dust! :mrgreen: Anyway Dimorphos has a pretty tail! 😘
Dogs-tilting-their-heads.jpg
Aren't they cute! I've seen these guys before 8-)
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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by johnnydeep » Wed Oct 05, 2022 7:55 pm

So, "the initial dot is primarily Dimorphos's larger companion: asteroid Didymos." means that the central sphere we see at first is really the combined images of Dimorphos and Didymos, possibly with Dimorphos partially or fully overlapping Didymos?
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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by MarkBour » Mon Oct 17, 2022 11:46 pm

johnnydeep wrote: Wed Oct 05, 2022 7:55 pm So, "the initial dot is primarily Dimorphos's larger companion: asteroid Didymos." means that the central sphere we see at first is really the combined images of Dimorphos and Didymos, possibly with Dimorphos partially or fully overlapping Didymos?
I think the resolution is such that the entire orbit of Dimorphos is within the single pixel. So the whole 2-body system at all times is just one tiny blob in this. Not so the ejecta plume -- we can see some resolution of it as it gets large, until it dissipates into invisibility.
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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by johnnydeep » Tue Oct 18, 2022 2:50 pm

MarkBour wrote: Mon Oct 17, 2022 11:46 pm
johnnydeep wrote: Wed Oct 05, 2022 7:55 pm So, "the initial dot is primarily Dimorphos's larger companion: asteroid Didymos." means that the central sphere we see at first is really the combined images of Dimorphos and Didymos, possibly with Dimorphos partially or fully overlapping Didymos?
I think the resolution is such that the entire orbit of Dimorphos is within the single pixel. So the whole 2-body system at all times is just one tiny blob in this. Not so the ejecta plume -- we can see some resolution of it as it gets large, until it dissipates into invisibility.
Still doesn't make sense to me. I see "objects" that are way bigger than single pixels in the short video. And I'm still not sure why the multi-pixel blob starts out as a small sphere, then expands to a larger sphere before having a large part of it blown off (presumably by the DART impactor). Unless the "larger sphere" is really just the impact debris before it clearly separates from Dimorphos? Yeah, I suppose that must be it. It would have helped to have the moment of impact clearly indicated in the video.
DART hitting Dimorphos.JPG
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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by Chris Peterson » Tue Oct 18, 2022 3:03 pm

johnnydeep wrote: Tue Oct 18, 2022 2:50 pm
MarkBour wrote: Mon Oct 17, 2022 11:46 pm
johnnydeep wrote: Wed Oct 05, 2022 7:55 pm So, "the initial dot is primarily Dimorphos's larger companion: asteroid Didymos." means that the central sphere we see at first is really the combined images of Dimorphos and Didymos, possibly with Dimorphos partially or fully overlapping Didymos?
I think the resolution is such that the entire orbit of Dimorphos is within the single pixel. So the whole 2-body system at all times is just one tiny blob in this. Not so the ejecta plume -- we can see some resolution of it as it gets large, until it dissipates into invisibility.
Still doesn't make sense to me. I see "objects" that are way bigger than single pixels in the short video. And I'm still not sure why the multi-pixel blob starts out as a small sphere, then expands to a larger sphere before having a large part of it blown off (presumably by the DART impactor). Unless the "larger sphere" is really just the impact debris before it clearly separates from Dimorphos? Yeah, I suppose that must be it. It would have helped to have the moment of impact clearly indicated in the video.

DART hitting Dimorphos.JPG
These objects are, indeed, smaller than single pixels from ground-based telescopes. As with stars, the apparent size is a consequence of diffraction and scatter, and is related to intensity. The initial dust cloud considerably increased the albedo of the asteroid, and that increased brightness is seen as an increase in apparent size. It isn't until the dust cloud becomes large enough that we actually resolve the event.
Chris

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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by johnnydeep » Tue Oct 18, 2022 3:21 pm

Chris Peterson wrote: Tue Oct 18, 2022 3:03 pm
johnnydeep wrote: Tue Oct 18, 2022 2:50 pm
MarkBour wrote: Mon Oct 17, 2022 11:46 pm

I think the resolution is such that the entire orbit of Dimorphos is within the single pixel. So the whole 2-body system at all times is just one tiny blob in this. Not so the ejecta plume -- we can see some resolution of it as it gets large, until it dissipates into invisibility.
Still doesn't make sense to me. I see "objects" that are way bigger than single pixels in the short video. And I'm still not sure why the multi-pixel blob starts out as a small sphere, then expands to a larger sphere before having a large part of it blown off (presumably by the DART impactor). Unless the "larger sphere" is really just the impact debris before it clearly separates from Dimorphos? Yeah, I suppose that must be it. It would have helped to have the moment of impact clearly indicated in the video.

DART hitting Dimorphos.JPG
These objects are, indeed, smaller than single pixels from ground-based telescopes. As with stars, the apparent size is a consequence of diffraction and scatter, and is related to intensity. The initial dust cloud considerably increased the albedo of the asteroid, and that increased brightness is seen as an increase in apparent size. It isn't until the dust cloud becomes large enough that we actually resolve the event.
Thanks. And, wow - these astronomical images sure can be deceiving for those who don't know all the subtle imaging limitations!
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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by MarkBour » Wed Oct 19, 2022 6:04 pm

johnnydeep wrote: Tue Oct 18, 2022 3:21 pm
Chris Peterson wrote: Tue Oct 18, 2022 3:03 pm
johnnydeep wrote: Tue Oct 18, 2022 2:50 pm

Still doesn't make sense to me. I see "objects" that are way bigger than single pixels in the short video. And I'm still not sure why the multi-pixel blob starts out as a small sphere, then expands to a larger sphere before having a large part of it blown off (presumably by the DART impactor). Unless the "larger sphere" is really just the impact debris before it clearly separates from Dimorphos? Yeah, I suppose that must be it. It would have helped to have the moment of impact clearly indicated in the video.

DART hitting Dimorphos.JPG
These objects are, indeed, smaller than single pixels from ground-based telescopes. As with stars, the apparent size is a consequence of diffraction and scatter, and is related to intensity. The initial dust cloud considerably increased the albedo of the asteroid, and that increased brightness is seen as an increase in apparent size. It isn't until the dust cloud becomes large enough that we actually resolve the event.
Thanks. And, wow - these astronomical images sure can be deceiving for those who don't know all the subtle imaging limitations!
Yes, thanks, Chris. I guess I had it mostly right, but am glad to get confirmation from someone who knows in far more detail about the diffraction and scatter that can make unresolved light sources appear larger than one pixel in images.
Mark Goldfain

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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by MarkBour » Wed Oct 19, 2022 6:13 pm

There was some interesting further discussion of the DART findings on a YouTube comments section.

It seems that the initial finding is that Dimorphos slowed down a lot more than would have been predicted by calculating the inertia of the DART spacecraft. I and others were wondering what effects might have caused this. My guess was that perhaps some volatile internal content in Dimorphos was heated from the impact and outgassed, giving additional thrust. Others mentioned that just the heating itself of one part of the asteroid could have provided some "thrust". It will be interesting to see what the experts eventually conclude. In any case, it already seems to show that there is no substitute for actual experiments.
Mark Goldfain

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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by Chris Peterson » Wed Oct 19, 2022 8:19 pm

MarkBour wrote: Wed Oct 19, 2022 6:13 pm There was some interesting further discussion of the DART findings on a YouTube comments section.

It seems that the initial finding is that Dimorphos slowed down a lot more than would have been predicted by calculating the inertia of the DART spacecraft. I and others were wondering what effects might have caused this. My guess was that perhaps some volatile internal content in Dimorphos was heated from the impact and outgassed, giving additional thrust. Others mentioned that just the heating itself of one part of the asteroid could have provided some "thrust". It will be interesting to see what the experts eventually conclude. In any case, it already seems to show that there is no substitute for actual experiments.
I think it probably comes down to the nature of the body- where it lies on a range of solid rock to loosely bound boulders and gravel.
Chris

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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by Cousin Ricky » Mon Oct 24, 2022 11:53 pm

Cousin Ricky wrote: Wed Oct 05, 2022 5:48 am What’s up with this? The video as posted is too large to fit on my screen, so I chose Watch on YouTube, but all I get are right wing propaganda shorts.
YouTube Shorts is broken. Since the day this APOD was posted, when I click on a YouTube Short, I almost always get a totally random video, and have to back out and try again.

Unless YouTube is doing a bait-and-switch on purpose. But The Google would never be evil. Would it?

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Re: APOD: Expanding Plume from DART's Impact (2022 Oct 05)

Post by johnnydeep » Tue Oct 25, 2022 1:35 pm

Cousin Ricky wrote: Mon Oct 24, 2022 11:53 pm
Cousin Ricky wrote: Wed Oct 05, 2022 5:48 am What’s up with this? The video as posted is too large to fit on my screen, so I chose Watch on YouTube, but all I get are right wing propaganda shorts.
YouTube Shorts is broken. Since the day this APOD was posted, when I click on a YouTube Short, I almost always get a totally random video, and have to back out and try again.

Unless YouTube is doing a bait-and-switch on purpose. But The Google would never be evil. Would it?
It's working correctly for me on my PC. That is, when I click "Watch on YouTube" from the APOD post, I get that specific YouTube "short".
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