APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep 16)

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APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep 16)

Post by APOD Robot » Sun Sep 16, 2012 4:06 am

Image Saturn: Bright Tethys and Ancient Rings

Explanation: How old are Saturn's rings? No one is quite sure. One possibility is that the rings formed relatively recently in our Solar System's history, perhaps only about 100 million years ago when a moon-sized object broke up near Saturn. Evidence for a young ring age includes a basic stability analysis for rings, and the fact that the rings are so bright and relatively unaffected by numerous small dark meteor impacts. More recent evidence, however, raises the possibility that some of Saturn's rings may be billions of years old and so almost as old as Saturn itself. Inspection of images by the Saturn-orbiting Cassini spacecraft indicates that some of Saturn's ring particles temporarily bunch and collide, effectively recycling ring particles by bringing fresh bright ices to the surface. Seen here, Saturn's rings were imaged in their true colors by the robotic Cassini in late October. Icy bright Tethys, a moon of Saturn likely brightened by a sandblasting rain of ice from sister moon Enceladus, is visible in front of the darker rings.

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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by neufer » Sun Sep 16, 2012 4:30 am


How old are Saturn's rings?
  • As old as dirt!
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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by Ann » Sun Sep 16, 2012 4:44 am

neufer wrote:

How old are Saturn's rings?
  • As old as dirt!
Could be. They are yellowish. When old people turn first gray, then white, their white hair sometimes looks yellowish. Saturn, if you ask me, is yellowish, hirsute rings and all.

I love the different albedos of the moons. Often you don't understand that the moons aren't all equally bright when you see portraits of the moons as individuals, because there is a tendency to "equalize" their reflectivity. Today's APOD proves that Tethys sure is a shiner. You can even see the impact at right.

Ouch!

Ann
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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by owlice » Sun Sep 16, 2012 8:21 am

More images of Saturn and its moons are here.
A closed mouth gathers no foot.

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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by Ken » Sun Sep 16, 2012 8:49 am

Not Found

The requested URL /apod/image/1209/tethysrings_cassini_1920.jpg was not found on this server.

Hey, guys, hope the webmasters here don't write mission software...

rghoeing@buffalo.edu

Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by rghoeing@buffalo.edu » Sun Sep 16, 2012 10:44 am

Beautiful picture; unfathomably ancient, modern art.

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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by orin stepanek » Sun Sep 16, 2012 12:18 pm

rghoeing@buffalo.edu wrote:Beautiful picture; unfathomably ancient, modern art.
True! 8-)
Orin

Smile today; tomorrow's another day!

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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by Moonlady » Sun Sep 16, 2012 12:19 pm

Ann wrote:
neufer wrote:

How old are Saturn's rings?
  • As old as dirt!
Could be. They are yellowish. When old people turn first gray, then white, their white hair sometimes looks yellowish. Saturn, if you ask me, is yellowish, hirsute rings and all.

I love the different albedos of the moons. Often you don't understand that the moons aren't all equally bright when you see portraits of the moons as individuals, because there is a tendency to "equalize" their reflectivity. Today's APOD proves that Tethys sure is a shiner. You can even see the impact at right.

Ouch!

Ann

Saturn's rings is it's beard? :old: never thought this way. Will Jupiter's ring turn sometime it's color (too)?
Thethys reminds me of the death star, ta ta ta, taaat ta taaaaaaaa.....

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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by emc » Sun Sep 16, 2012 1:10 pm

Saturn’s rings are so old they need "assistance" to get around…

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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by owlice » Sun Sep 16, 2012 1:12 pm

Wow, Ed, thanks for that link! What a spectacular shot!!

geckzilla is right: it's like Cassini doesn't even need to try.

The whole system is wowsers1!



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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by Boomer12k » Sun Sep 16, 2012 1:27 pm

I thought Saturn's Rings were cause by Ice Geysers from Enceladus....and here it says Tethys is also covered by ice from Enceledus...if this were a Murder Mystery...I think we have a suspect....who has "A Prior"....


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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by neufer » Sun Sep 16, 2012 2:48 pm

Boomer12k wrote:
I thought Saturn's Rings were cause by Ice Geysers from Enceladus....
and here it says Tethys is also covered by ice from Enceledus...
if this were a Murder Mystery...I think we have a suspect....who has "A Prior"....
  • Enceledus is only responsible for the distant diffuse E Ring:
http://en.wikipedia.org/wiki/Enceladus_%28moon%29 wrote: <<The E Ring is the widest and outermost ring of Saturn. It is an extremely wide but very diffuse disk of microscopic icy or dusty material, beginning at the orbit of Mimas and ending somewhere around the orbit of Rhea, though some observations suggest that it extends beyond the orbit of Titan, making it 1,000,000 km wide. However, numerous mathematical models show that such a ring is unstable, with a lifespan between 10,000 and 1,000,000 years. Therefore, particles composing it must be constantly replenished. Enceladus is orbiting inside this ring, in a place where it is narrowest but present in its highest density. Therefore, several theories suspected Enceladus to be the main source of particles for the E Ring. This hypothesis was supported by Cassini's flyby.

There are actually two distinct mechanisms feeding the ring with particles. The first, and probably the most important, source of particles comes from the cryovolcanic plume in the South polar region of Enceladus. While a majority of particles fall back to the surface, some of them escape Enceladus's gravity and enter orbit around Saturn, since Enceladus's escape velocity is only 866 km/h. The second mechanism comes from meteoric bombardment of Enceladus, raising dust particles from the surface. This mechanism is not unique to Enceladus, but is valid for all Saturn's moons orbiting inside the E Ring.>>
http://en.wikipedia.org/wiki/Rings_of_Saturn wrote:

<<The rings of Saturn are the most extensive planetary ring system of any planet in the Solar System. They consist of countless small particles, ranging in size from micrometres to metres, that form clumps that in turn orbit about Saturn. The ring particles are made almost entirely of water ice, with some contamination from dust and other chemicals. The origin of them is pretty much a complete mystery. The total mass of the rings is about 3 x 1019 kg [vs. Enceledus = 10.8 × 1019 kg ]. There have been recent claims, yet unverified, that this is an underestimate due to clumping in the rings and the mass may be three times this figure.

In December 2010, National Geographic suggested that the rings of Saturn could be the remains of a giant lost moon that was stripped of its icy shell before it crashed into the planet.

Data from the Cassini space probe indicate that the rings of Saturn possess their own atmosphere, independent of that of the planet itself. The atmosphere is composed of molecular oxygen gas (O2) produced when ultraviolet light from the Sun interacts with water ice in the rings. Chemical reactions between water molecule fragments and further ultraviolet stimulation create and eject, among other things, O2. According to models of this atmosphere, H2 is also present. The O2 and H2 atmospheres are so sparse that if the entire atmosphere were somehow condensed onto the rings, it would be about one atom thick. The rings also have a similarly sparse OH (hydroxide) atmosphere. Like the O2, this atmosphere is produced by the disintegration of water molecules, though in this case the disintegration is done by energetic ions that bombard water molecules ejected by Saturn's moon Enceladus. This atmosphere, despite being extremely sparse, was detected from Earth by the Hubble Space Telescope>>
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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by Ann » Sun Sep 16, 2012 3:12 pm

Image

Guess what, the E ring is blue!!!!



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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by neufer » Sun Sep 16, 2012 4:28 pm

Ann wrote:
Image

Guess what, the E ring is blue!!!!
You call that blue?!

Blue, a. [OE. bla, blo, blew, blue, Sw. bl, D. blauw, OHG. blo, G. blau.] Low in spirits; melancholy; as, to feel blue.
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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by dlw » Sun Sep 16, 2012 4:30 pm

This particular perspective seems to exaggerate the apparent height of the Odysseus impact crater walls -- or does it?

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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by Ann » Sun Sep 16, 2012 4:32 pm

neufer wrote:
Ann wrote:
Image

Guess what, the E ring is blue!!!!
You call that blue?!

Blue, a. [OE. bla, blo, blew, blue, Sw. bl, D. blauw, OHG. blo, G. blau.] Low in spirits; melancholy; as, to feel blue.
Image
So let me amend it and call the E ring "blå"! In Swedish, "blå" refers to the color only. We don't associate the color "blå" with sadness!


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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by ta152h0 » Sun Sep 16, 2012 6:30 pm

and a nine year old would ask " what is that ball floating on ? " and i would say " that is an opportunity I will not let slip away "
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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by zbvhs » Sun Sep 16, 2012 6:39 pm

Question is: why do the outer gas giants all have rings? The Sun has one as well (the asteroids). Do they represent some gravitational stability boundary or did it all just turn out that way?
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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by neufer » Sun Sep 16, 2012 6:58 pm

Ann wrote:
neufer wrote:
Ann wrote:
Guess what, the E ring is blue!!!!
You call that blue?!

Blue, a. [OE. bla, blo, blew, blue, Sw. bl, D. blauw, OHG. blo, G. blau.] Low in spirits; melancholy; as, to feel blue.
So let me amend it and call the E ring "blå"! In Swedish, "blå" refers to the color only. We don't associate the color "blå" with sadness!
http://www.websters-online-dictionary.com/definitions/blah wrote:
<<In English, "blah" is used within a compound noun, suggesting a psychological state or expressing an opinion; for example, February blahs describes a generally depressed condition during winter. It is also viewed as a word expressing indifference, or lack of a preference. It may also be used to imply that something is not impressive, or it is boring, bland, or without character.

Several alternatives or variants of the word can be observed today, such as bleh, blech, bla, meh or bah, although some differences may be perceived in certain contexts. Generally these variants would only be used in place of blah to show unimportance, disgust or disinterest. The word used is typically left to individual preference.

As of 1913, Webster's Dictionary had not listed this word. It appeared roughly between 1915-1920, meaning "idle, meaningless talk". Its meaning soon was also likened to "bland" or "dull". In 1922 Collier's utilized the term "blah blah" to label a tedious length speech on a subject. It was later used to reflect a depressive state in the late 1960s, first attested in 1969, and believed to have been influenced by the blues. Blah most of the time usually means blank thoughts or expressions.

The word likely originated as an echoic, or onomatopoeia. In this case representing a block of speech that is drawn out, boring or vacuous enough, so that all that is heard is the repetition, "blah, blah, blah".>>
Last edited by neufer on Sun Sep 16, 2012 7:20 pm, edited 1 time in total.
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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by neufer » Sun Sep 16, 2012 7:03 pm

zbvhs wrote:
Question is: why do the outer gas giants all have rings?

The Sun has one as well (the asteroids).
For the same reason that they all have lots of satellites.

A ring is simply another satellite (or, if you prefer, a former satellite or a failed satellite).
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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by saturno2 » Sun Sep 16, 2012 11:42 pm

Saturn, my favorite planet.
I think that the structure and formation of the rings have to see with the rapid speed of rotation of Saturn.

Zoliv

Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by Zoliv » Mon Sep 17, 2012 2:18 pm

Isn't the moon in front of the pic Mimas ?

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Re: APOD: Saturn: Bright Tethys and Ancient Rings (2012 Sep

Post by Anthony Barreiro » Mon Sep 17, 2012 8:02 pm

Ann wrote: ... .

I love the different albedos of the moons. Often you don't understand that the moons aren't all equally bright when you see portraits of the moons as individuals, because there is a tendency to "equalize" their reflectivity. Today's APOD proves that Tethys sure is a shiner. You can even see the impact at right.

Ouch!

Ann
The different albedos of Saturn's moons have a huge effect on their visibility through a small telescope. Hyperion is hard to see because it is so dark. Iapetus is much brighter and easier to see when its bright side is facing toward Earth than when its dark side is turned toward us.
May all beings be happy, peaceful, and free.