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

[APOD Robot]

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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[Joules]

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

[Zuben L. Genubi]

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

[Craine]

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.

[Ron-Astro Pharmacist]

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

220px-Escher's_Relativity.jpg (20.93 KiB) Viewed 3645 times

M. C . Escher lives on as a comet.

EscherSelf1929.jpg (27.98 KiB) Viewed 3645 times

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.

[Markus Schwarz]

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.

[bixdugan@aol.com]

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

[Craine]

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?

[Dad is watching]

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?

[Craine]

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]

it looks likely the comet will break into two in August

[Boomer12k]

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

utterly fascinating...

:---[===] *

[Boomer12k]

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

:---[===] *

[Chris Peterson]

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.

[neufer]

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.

[Chris Peterson]

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.