APOD: A Cliff Looming on Comet 67P (2015 May 20)

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APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by APOD Robot » Wed May 20, 2015 4:06 am

Image A Cliff Looming on Comet 67P

Explanation: What that looming behind this gravel-strewn hill on Comet Churyumov–Gerasimenko? A jagged cliff. The unusual double-lobed nucleus of Comet 67P/Churyumov–Gerasimenko lends itself to unusual and dramatic vistas, another of which has been captured by the Rosetta spacecraft that arrived at the comet last September. The featured cometscape, taken last October and digitally enhanced, spans about 850 meters across. Meanwhile, Comet Churyumov–Gerasimenko continues to sprout jets as it nears its closest approach to the Sun in August. Along the way, Rosetta will continue listening for signals from Philae, a probe that landed on the nucleus but rebounded to an unknown surface location last November. If newly exposed to sunlight, Philae might regain enough energy to again signal Rosetta.

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Joules » Wed May 20, 2015 11:29 am

That is very disturbing.
Landscapes are not supposed to look like that.

Zuben L. Genubi

Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Zuben L. Genubi » Wed May 20, 2015 11:59 am

Perhaps Philae will receive enough light to regain function--or perhaps that cliff will collapse and crush it to smithereens!

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Craine » Wed May 20, 2015 12:12 pm

That cliff may be massive...but it weighs little in that low gravity. I seem to recall a number of ~1/10000 of Earths surface gravity.

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Ron-Astro Pharmacist » Wed May 20, 2015 2:26 pm

Joules wrote:That is very disturbing.
Landscapes are not supposed to look like that.
220px-Escher's_Relativity.jpg
M. C . Escher lives on as a comet.
EscherSelf1929.jpg
Even his hair had odd angles.

http://en.wikipedia.org/wiki/M._C._Escher

Add to that "Relativity" and it proves he was a wise guy that liked to add strange dimensions to our lives. At least he could draw. :wink:
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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Markus Schwarz » Wed May 20, 2015 3:03 pm

The drawing by Escherr reminds of a talk from one member of the Rosetta team. Since the comet is irregular shaped defining an equator etc. is non-trivial. Here is a map of the comet they came up with.

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by bixdugan@aol.com » Wed May 20, 2015 3:59 pm

Hey wait a minute! This is just a picture of the Vasquez Rocks!

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Craine » Wed May 20, 2015 4:27 pm

Markus Schwarz wrote:The drawing by Escherr reminds of a talk from one member of the Rosetta team. Since the comet is irregular shaped defining an equator etc. is non-trivial. Here is a map of the comet they came up with.
Anybody up for a game of Risk?

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Dad is watching » Wed May 20, 2015 6:19 pm

I was wondering about the light colored stuff on the left side of the image. It looks like snow on the surface but I don't think that is possible. Snow flakes grow as six pointed ice crystals from moisture in the atmosphere, but that cannot be the case here. Is this some form of ice pellet or ice flake on the surface, or maybe some sort of frozen condensate? Or is it just rock dust? What do you think?

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Craine » Wed May 20, 2015 6:34 pm

Dad is watching wrote:I was wondering about the light colored stuff on the left side of the image. It looks like snow on the surface but I don't think that is possible. Snow flakes grow as six pointed ice crystals from moisture in the atmosphere, but that cannot be the case here. Is this some form of ice pellet or ice flake on the surface, or maybe some sort of frozen condensate? Or is it just rock dust? What do you think?
From what I understand the surface material is mostly rock and dust. Any water ice on near the surface would be the first to evaporate/sublimate, leaving the solid rock and dust behind. Water ice deeper in will get slowly warmed up when the comet nears the sun, until some of that too may escape gradually, or sometimes in outburst.
But these photos really just show rock and dust. The real color is much darker, as on average it only reflects about 6% of the light (nearly black).

kelleherkelk

Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by kelleherkelk » Wed May 20, 2015 6:51 pm

it looks likely the comet will break into two in August

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Boomer12k » Wed May 20, 2015 11:10 pm

Bleak and Barren...looks like you could cook an egg on it....

utterly fascinating...

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Boomer12k » Wed May 20, 2015 11:14 pm

"Earth to Major Philae...."???

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Chris Peterson » Wed May 20, 2015 11:16 pm

kelleherkelk wrote:it looks likely the comet will break into two in August
I doubt it. It doesn't get near enough the Sun for tidal forces to be significant, and forces generated by outgassing are extremely small. This comet has made a great many orbits without breaking apart.
Chris

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by neufer » Thu May 21, 2015 12:50 pm

Chris Peterson wrote:
kelleherkelk wrote:
it looks likely the comet will break into two in August
I doubt it. It doesn't get near enough the Sun for tidal forces to be significant, and forces generated by outgassing are extremely small.
This comet has made a great many orbits without breaking apart.
Outgassing could, however, cause the neck to break and the head to fall down.
Art Neuendorffer

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Re: APOD: A Cliff Looming on Comet 67P (2015 May 20)

Post by Chris Peterson » Thu May 21, 2015 1:59 pm

neufer wrote:
Chris Peterson wrote:
kelleherkelk wrote:it looks likely the comet will break into two in August
I doubt it. It doesn't get near enough the Sun for tidal forces to be significant, and forces generated by outgassing are extremely small.
This comet has made a great many orbits without breaking apart.
Outgassing could, however, cause the neck to break and the head to fall down.
Possibly, depending on the amount of volatile material in the neck. But even so, I doubt outgassing would generate enough force to cause a break. Ultimately, the neck will fail because of tidal stress or because of the stress of mutual gravitational attraction between the ends. Outgassing will just weaken the structure. But that neck is quite large. This is a short period comet. It has made thousands of orbits around the Sun as a lobed object. Eventually it will probably split (and settle into a new lobed structure). But probably not this time around.
Chris

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