Comments and questions about the
APOD on the main view screen.
-
APOD Robot
- Otto Posterman
- Posts: 5579
- Joined: Fri Dec 04, 2009 3:27 am
Post
by APOD Robot » Sat Jun 15, 2019 4:06 am
Stereo Helene
Explanation: Get out your
red/blue glasses and float next to Helene, small, icy moon of Saturn.
Appropriately named, Helene is one of four known Trojan moons, so called because it orbits at a
Lagrange point. A Lagrange point is a gravitationally stable position near two massive bodies, in this case
Saturn and larger moon Dione. In fact, irregularly shaped ( about 36 by 32 by 30 kilometers) Helene orbits at Dione's leading Lagrange point while brotherly ice moon Polydeuces follows at Dione's trailing Lagrange point.
The sharp stereo anaglyph was constructed from two Cassini images captured during
a close flyby in 2011. It shows part of the Saturn-facing hemisphere of Helene mottled with craters and gully-like features.
-
BDanielMayfield
- Don't bring me down
- Posts: 2524
- Joined: Thu Aug 02, 2012 11:24 am
- AKA: Bruce
- Location: East Idaho
Post
by BDanielMayfield » Sat Jun 15, 2019 11:31 am
I note the features that look like gullies are called "gully-like" in the explanation. Is gravity too weak on a body this small to carve erosional gullies?
P.S. That wasn't meant to be critical of the explanation's wording. Just seeking info.
Bruce
Last edited by BDanielMayfield on Sat Jun 15, 2019 12:53 pm, edited 1 time in total.
Just as zero is not equal to infinity, everything coming from nothing is illogical.
-
orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
Post
by orin stepanek » Sat Jun 15, 2019 12:34 pm
Nicely done stereo; it loos like the head of some kind of animal!
Is it pure ice?
Orin
Smile today; tomorrow's another day!
-
Chris Peterson
- Abominable Snowman
- Posts: 18588
- Joined: Wed Jan 31, 2007 11:13 pm
- Location: Guffey, Colorado, USA
Post
by Chris Peterson » Sat Jun 15, 2019 12:45 pm
orin stepanek wrote: ↑Sat Jun 15, 2019 12:34 pm
Nicely done stereo; it loos like the head of some kind of animal! :D Is it pure ice?
Define "ice". Define "pure".
-
Boomer12k
- :---[===] *
- Posts: 2691
- Joined: Sun Apr 22, 2007 12:07 am
Post
by Boomer12k » Sat Jun 15, 2019 8:37 pm
Really good 3D effect for me. This is one of the very few that actually APPEAR to bring out the objects from my monitor. Like about 6 inches...especially on the left side.
I wonder what the striations sweeping through some areas are... grooves from ice evaporation? There are places that look like "water pathways", and such... really puzzling to me... solar wind? Some are really long, or is it just "rough terrain"?
Really good work...
:---[===] *
Last edited by Boomer12k on Sat Jun 15, 2019 8:45 pm, edited 2 times in total.
-
Boomer12k
- :---[===] *
- Posts: 2691
- Joined: Sun Apr 22, 2007 12:07 am
Post
by Boomer12k » Sat Jun 15, 2019 8:39 pm
orin stepanek wrote: ↑Sat Jun 15, 2019 12:34 pm
Nicely done stereo; it loos like the head of some kind of animal!
Is it pure ice?
I don't think it is "pure ice", but ice and rocky mix...
:---[===] *
-
orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
Post
by orin stepanek » Sun Jun 16, 2019 12:24 pm
Chris Peterson wrote: ↑Sat Jun 15, 2019 12:45 pm
orin stepanek wrote: ↑Sat Jun 15, 2019 12:34 pm
Nicely done stereo; it loos like the head of some kind of animal!
Is it pure ice?
Define "ice". Define "pure".
Ice=frozen water in this case! Pure in this scenario; i was referring to mostly! ( I be didn't know I had to be so precise!)
Orin
Smile today; tomorrow's another day!
-
orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
Post
by orin stepanek » Sun Jun 16, 2019 12:26 pm
Boomer12k wrote: ↑Sat Jun 15, 2019 8:39 pm
orin stepanek wrote: ↑Sat Jun 15, 2019 12:34 pm
Nicely done stereo; it loos like the head of some kind of animal!
Is it pure ice?
I don't think it is "pure ice", but ice and rocky mix...
:---[===] *
Thanks Boomer!
Orin
Smile today; tomorrow's another day!
-
neufer
- Vacationer at Tralfamadore
- Posts: 18805
- Joined: Mon Jan 21, 2008 1:57 pm
- Location: Alexandria, Virginia
Post
by neufer » Sun Jun 16, 2019 3:59 pm
Our Moon is the result of a glancing planetary collision with the Earth resulting in a
mostly mantle moon.
If Helene was the result of a glancing collision with Dione the result would be a
mostly ice moon.
Art Neuendorffer
-
orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
Post
by orin stepanek » Mon Jun 17, 2019 11:10 am
neufer wrote: ↑Sun Jun 16, 2019 3:59 pm
Our Moon is the result of a glancing planetary collision with the Earth resulting in a
mostly mantle moon.
If Helene was the result of a glancing collision with Dione the result would be a
mostly ice moon.
Thanks Art!
Orin
Smile today; tomorrow's another day!