IPB

Welcome Guest ( Log In | Register )

11 Pages V  « < 3 4 5 6 7 > »   
Reply to this topicStart new topic
Rev 126 - Feb 4-22, 2010 - Mimas (main target), Tethys, Iapetus, Calypso and mutual events too
dilo
post Feb 15 2010, 05:59 PM
Post #61


Senior Member
****

Group: Members
Posts: 2442
Joined: 15-January 05
From: center Italy
Member No.: 150



Feb, 14 sequence animation:
Attached Image

Note the curious sudden illumination change on Epimtheus from a body on the right, perhaps from Janus itself (strange geometry, however) rolleyes.gif
Attached thumbnail(s)
Attached Image
 


--------------------
- Marco -
Go to the top of the page
 
+Quote Post
ugordan
post Feb 15 2010, 06:33 PM
Post #62


Senior Member
****

Group: Members
Posts: 3559
Joined: 1-October 05
From: Croatia
Member No.: 523



QUOTE (dilo @ Feb 15 2010, 06:59 PM) *
Note the curious sudden illumination change on Epimtheus from a body on the right

Looks like "sunset" to me.


--------------------
Go to the top of the page
 
+Quote Post
volcanopele
post Feb 15 2010, 06:37 PM
Post #63


Senior Member
****

Group: Moderator
Posts: 2852
Joined: 11-February 04
From: Tucson, AZ
Member No.: 23



Nice catch about the change in illumination on Epimetheus. I doubt it is from Janus since that moon is clearly on the OTHER side of Epimetheus from those craters. I think we are just seeing a slight bit of rotation on Epimetheus, and the Sun is setting on the far rims of three impact craters just beyond the evening terminator.

I have to admit that I started to doubt that explanation since I suddenly thought that north might be up, so the terminator we are seeing would be the dawn one... But nope, south is up in your animation, so my explanation holds...


--------------------
&@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io
Go to the top of the page
 
+Quote Post
belleraphon1
post Feb 15 2010, 07:16 PM
Post #64


Member
***

Group: Members
Posts: 719
Joined: 29-December 05
From: NE Oh, USA
Member No.: 627



I do not usually throw in attachments so bare with me...

But in this Mimas image I am not convinced all the low albedo stuff is due to shadow.

Attached Image


It is from NAC image N00151508. Also if you look at dilo's colorized global image you can see a few darkish spots in the high phase region. Kinda like the Rhea ring impactors but more dispersed (not in a line)?

Interesting.

Craig
Go to the top of the page
 
+Quote Post
Explorer1
post Feb 15 2010, 07:45 PM
Post #65


Member
***

Group: Members
Posts: 853
Joined: 13-February 10
From: British Columbia
Member No.: 5221



Wow this stuff is truly great. Honestly if it wasn't for the central peak Herschel almost looks like it formed some other way. It's just so irregular and different from other big craters, like on the moon or Callisto.
Mysteries abound!
Go to the top of the page
 
+Quote Post
Juramike
post Feb 15 2010, 07:50 PM
Post #66


Senior Member
****

Group: Moderator
Posts: 2676
Joined: 10-November 06
From: Pasadena, CA
Member No.: 1345



Compare it to Rhea. Many of the larger craters on that moon are also irregular.

Mass wasting and slumping the crater walls of Herschel seem evident.

EDIT: Looking at the picture that Craig posted it seems that there is a tendency for the walls to form and slump along parallel lines going from lower left to top right.


--------------------
Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
Go to the top of the page
 
+Quote Post
Ian R
post Feb 15 2010, 08:01 PM
Post #67


Member
***

Group: Members
Posts: 546
Joined: 18-July 05
From: Plymouth, UK
Member No.: 437



Here are my two 'bouncy' animations of this mutual event:

Epimetheus-centric:

Attached Image

Janus-centric:

Attached Image


--------------------
Go to the top of the page
 
+Quote Post
Adam Hurcewicz
post Feb 15 2010, 08:19 PM
Post #68


Junior Member
**

Group: Members
Posts: 59
Joined: 29-January 10
From: Poland
Member No.: 5205



- Full quote deleted. Use the "add reply" button at the bottom of the page. -

Nice work !

Your animations show rotations of this monns


--------------------
Adam Hurcewicz from Poland
Go to the top of the page
 
+Quote Post
dilo
post Feb 15 2010, 08:56 PM
Post #69


Senior Member
****

Group: Members
Posts: 2442
Joined: 15-January 05
From: center Italy
Member No.: 150



Grat animations, Ian! (original quality is clearly better than mine...)
Gordan, you were right!


--------------------
- Marco -
Go to the top of the page
 
+Quote Post
Adam Hurcewicz
post Feb 15 2010, 09:06 PM
Post #70


Junior Member
**

Group: Members
Posts: 59
Joined: 29-January 10
From: Poland
Member No.: 5205



TETHYS in (IR1, G UV3)

ir1 N00151608
g N00151607
uv3 N00151606
Attached thumbnail(s)
Attached Image
 


--------------------
Adam Hurcewicz from Poland
Go to the top of the page
 
+Quote Post
Poolio
post Feb 15 2010, 09:08 PM
Post #71


Member
***

Group: Members
Posts: 128
Joined: 28-October 08
From: Boston, MA
Member No.: 4469



What we're seeing here is these two co-orbitals exchanging orbits, correct? It seems natural to think that the switching of orbits would need to cause temporary redirections of the moons from their normal elliptical orbits, and therefore the observed rotations and exposure of hidden surfaces to the sun.
Go to the top of the page
 
+Quote Post
Floyd
post Feb 15 2010, 09:23 PM
Post #72


Member
***

Group: Members
Posts: 589
Joined: 4-September 06
From: Boston
Member No.: 1102



I'm not exactly sure where they are in the process of exchanging orbits, but I think the relative movement we see here is mainly the changing perspective of Cassini as it rushes by.


--------------------
Floyd
Go to the top of the page
 
+Quote Post
Phil Stooke
post Feb 15 2010, 09:34 PM
Post #73


Senior Member
****

Group: Members
Posts: 5315
Joined: 5-April 05
From: Canada
Member No.: 227



This is not the orbital switch. There are several factors - the moving spacecraft, the moons moving relative to the sun and to each other.

Phil


--------------------
... because the Solar System ain't gonna map itself.
Go to the top of the page
 
+Quote Post
Poolio
post Feb 15 2010, 09:37 PM
Post #74


Member
***

Group: Members
Posts: 128
Joined: 28-October 08
From: Boston, MA
Member No.: 4469



But changing the observer's perspective couldn't account for the change in illumination of the subject. We must be seeing physical rotation of the moons themselves relative to the sun.
Go to the top of the page
 
+Quote Post
Phil Stooke
post Feb 15 2010, 09:38 PM
Post #75


Senior Member
****

Group: Members
Posts: 5315
Joined: 5-April 05
From: Canada
Member No.: 227



"in this Mimas image I am not convinced all the low albedo stuff is due to shadow."

These patches don't look unusually dark in images with more overhead lighting, which you can see further up the thread. - but there are real dark spots in places further east.

Phil


--------------------
... because the Solar System ain't gonna map itself.
Go to the top of the page
 
+Quote Post

11 Pages V  « < 3 4 5 6 7 > » 
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 18th April 2014 - 03:04 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.