APOD: Ultima Thule Rotation Gif (2019 Jan 04)

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APOD: Ultima Thule Rotation Gif (2019 Jan 04)

Post by APOD Robot » Fri Jan 04, 2019 5:17 am

Image Ultima Thule Rotation Gif

Explanation: Ultima Thule is the most distant world explored by a spacecraft from Earth. In the dim light 6.5 billion kilometers from the Sun, the New Horizons spacecraft captured these two frames 38 minutes apart as it sped toward the Kuiper belt world on January 1 at 51,000 kilometers per hour. A contact binary, the two lobes of Ultima Thule rotate together once every 15 hours or so. Shown as a blinking gif, the rotation between the frames produces a tantalizing 3D perspective of the most primitive world ever seen. Dubbed separately by the science team Ultima and Thule, the larger lobe Ultima, is about 19 kilometers in diameter. Smaller Thule is 14 kilometers across.

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Re: APOD: Ultima Thule Rotation Gif (2019 Jan 04)

Post by jks » Fri Jan 04, 2019 5:42 am

Please note that, at present, the date at the top says "2019 January 3".

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Case
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Re: APOD: Ultima Thule Rotation Gif (2019 Jan 04)

Post by Case » Fri Jan 04, 2019 7:40 am

Also, the Discuss link on the APOD page currently points to yesterday’s forum thread.

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Re: APOD: Ultima Thule Rotation Gif (2019 Jan 04)

Post by orin stepanek » Fri Jan 04, 2019 3:45 pm

Pretty good sized rock floating out there! I Hope it stays out there! :lol2: Amazing what man can do these days. 8-)
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Re: APOD: Ultima Thule Rotation Gif (2019 Jan 04)

Post by Chris Peterson » Fri Jan 04, 2019 11:53 pm

orin stepanek wrote:
Fri Jan 04, 2019 3:45 pm
Pretty good sized rock floating out there! I Hope it stays out there! :lol2: Amazing what man can do these days. 8-)
A good chance it's more ice than rock.
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Re: APOD: Ultima Thule Rotation Gif (2019 Jan 04)

Post by jks » Sat Jan 05, 2019 1:41 am

Case wrote:
Fri Jan 04, 2019 7:40 am
Also, the Discuss link on the APOD page currently points to yesterday’s forum thread.
Thanks, missed that, as I used a bookmark instead of the link.

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Re: APOD: Ultima Thule Rotation Gif (2019 Jan 04)

Post by neufer » Sat Jan 05, 2019 3:49 am

Chris Peterson wrote:
Fri Jan 04, 2019 11:53 pm
orin stepanek wrote:
Fri Jan 04, 2019 3:45 pm

Pretty good sized rock floating out there! I Hope it stays out there! :lol2: Amazing what man can do these days. 8-)
A good chance it's more ice than rock.
Kuiper belt objects are pretty dense to be considered mostly ice:

Code: Select all

Moon & KBOs	 Density   Diameter(km)
------------------------------------------
Moon              3.344      3474
.........................................
Pluto 	          1.87 	     2380
Eris 	          2.5 	     2326
Haumea 	          2.5	     1436
Makemake          1.4 	     1430
2007 OR10	  1.72 	     1253
Salacia 	  1.16        854
Art Neuendorffer

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Re: APOD: Ultima Thule Rotation Gif (2019 Jan 04)

Post by BDanielMayfield » Sat Jan 05, 2019 4:57 am

Well nil rotation is out as an explanation of the flat light curve. It was a very long odds long shot, but worth mentioning just in case this unlikely possibility proved out to be the solution.

I note however that the axis of rotation does not appear to be aligned with the centers of mass of the two lobes, as would be expected if the two parts merely orbited together I would think. Therefore, I suggest that Ultima and Thule formed separately but orbited the sun on nearby orbits. Their very low gravitational attraction brings them together with an impact slow enough to prevent the disruption of either body. Then they essentially freeze together into one object.

Bruce
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