Comments on: A trillion and five moons

By: Rolf Wucherer

Rolf Wucherer — Fri, 04 Nov 2011 02:53:55 +0000

Beautiful! Some day Cassini will run out of juice and, I guess, go into permanent orbit around Saturn. I suggest we make it an honorary moon! It, too, is not large enough to crush itself into a sphere, but we may be able to pinpoint its orbit. We could call it… Cassini!

By: Running rings around the competition « unbound page

Running rings around the competition « unbound page — Sun, 18 Sep 2011 22:34:43 +0000

[...] blame Phil Plait. His blog is an unending stream of pretty space pictures, and he’s been getting a little [...]

By: Keith Bowden

Keith Bowden — Wed, 14 Sep 2011 18:57:28 +0000

It never ceases to amaze me that no matter the resolution, or how close Cassini gets, the rings always seem both impossibly solid (though somewhat transparent) and impossibly thin. There never seems to be any area that’s thinner/thicker than the surrounding areas of rings, nor do they ever seem to resolve into individual fragments, a la the CGI in the opening credits on Star Trek: The Next Generation. (Or have I missed these photos?)

Beautiful stuff.

By: Gus

Gus — Wed, 14 Sep 2011 11:07:57 +0000

How long did the “window” last for Cassini to take this picture?

By: En la luna - Esceptica

En la luna - Esceptica — Wed, 14 Sep 2011 09:12:52 +0000

[...] imagen de lunas de Saturno (Via BadAstronomy) De izquierda a derecha, Janus, Pandora (en los anillos), Encélado, Mimas y Rea. Puedes ver la [...]

By: Messier Tidy Upper

Messier Tidy Upper — Wed, 14 Sep 2011 03:09:44 +0000

@2. Becca Stareyes : Thanks.

@9. Crux Australis & Jim Craig : Aptly enough Rhea the big moon in question is also thought to have rings itself :

http://en.wikipedia.org/wiki/Rings_of_Rhea

http://www.space.com/5051-saturn-moon-rings.html

http://www.youtube.com/watch?v=V7p9A3Gnwug&NR=1

@5. Mark : “I can’t wait until we’re seeing images like this of the Jovian system. Amazing!”

Did you miss the images from when they had the Galileo spaceprobe orbiting Jove then? Some of those were marvellous too.

By: Jim Craig

Jim Craig — Wed, 14 Sep 2011 01:32:09 +0000

Crux Australis, you and me both! Glad to see I wasn’t the only one.

By: Crux Australis

Crux Australis — Tue, 13 Sep 2011 22:25:52 +0000

At first, I counted only 4 moons; then I realized that big one on the right isn’t Saturn!

By: Neil NZ

Neil NZ — Tue, 13 Sep 2011 22:02:38 +0000

Is Cassini likely to be funded beyond 2017? If not, what will happen to it when the funds dry up?

By: Paul

Paul — Tue, 13 Sep 2011 20:37:51 +0000

Given that the rings are relatively thin, would it be possible to swing Cassini very close to them in order to observe moonlets up close? Perhaps in the late stages of Cassini’s mission?

By: Mike Dedmon

Mike Dedmon — Tue, 13 Sep 2011 18:16:11 +0000

RSS Feeds have changed. I now only seeing a small excerpt… Anything you could do to get them back to the full article would be GREATLY appreciated.

Love your stuff! Keep up the good work!

By: Anchor

Anchor — Tue, 13 Sep 2011 18:09:56 +0000

Becca @2 is right – they’re ALL mostly ice. It’s misleading to characterize the others as “rocky”: their relatively older surfaces are just dingier than Enceladus’ fresh coating.

By: QuietDesperation

QuietDesperation — Tue, 13 Sep 2011 18:00:12 +0000

Eh… (tilts head) need to move Enceladus a skosh to the right. (stares) Tilt the ring plane more.

Perfect! Get the camera! Now we make… (d r a m a t i c p a u s e) the magics!

By: Mark

Mark — Tue, 13 Sep 2011 17:59:14 +0000

I can’t wait until we’re seeing images like this of the Jovian system. Amazing!

By: IVAN3MAN_AT_LARGE

IVAN3MAN_AT_LARGE — Tue, 13 Sep 2011 17:43:15 +0000

MTU:

How large does a ring particle get before it counts as a moon or moonlet?

Becca Stareyes:

I think currently the informal definition is ‘anything we can see on its own and track’, [...].

Actually, anything larger than Rosie O’Donnell’s ass!

By: Rick

Rick — Tue, 13 Sep 2011 17:32:56 +0000

What a beautiful picture! Assuming that all the moons are in the ring plane (big assumption, I know), I hypothesize that the apparent distance above or below the plane is inversely proportional to the distance from the Cassini camera. That makes it Enceladus, Janus, Mimas, Rhea, Pandora in order of increasing distance, I think.

The camera is obviously not exactly in the ring plane, so it makes this a bit tricky to judge.

By: Nicholas Bohac

Nicholas Bohac — Tue, 13 Sep 2011 17:15:56 +0000

This was a great way to start out my day. Images like this are inspiring while also humbling, showing us just how small we are in the grand scheme of it all. This is definitely a desktop wallpaper.

By: Becca Stareyes

Becca Stareyes — Tue, 13 Sep 2011 16:17:56 +0000

BA, to correct your statement, Enceladus actually has a pretty high density relative to its sibling-moons — its brightness is more due to the fact its South Pole is actively spewing out frost, which coats the moon. Granted, even with its density, Enceladus is mostly ice, but it does have less ice than its sibling moons, just not on its surface.

Also MTU @ 1, I don’t think there’s a formal definition, but Pan, Daphnis and Aegaeon are on the small end — Pan and Daphnis are in the A ring itself, but have mostly cleared out nearby space (they’re in gaps in the outer A ring). Aegaeon is probably generating the G ring, but there may be other chunks of ice in there. I think currently the informal definition is ‘anything we can see on its own and track’, but some of the larger ‘propeller moonlets’ — unresolved 100 m (or so) chunks of ice in the A Ring that make propeller-shaped disturbances — have become things we can predict well enough to identify from orbit to orbit. We haven’t seen the moonlets themselves (only the disturbances in the ring material), but that’s more a function of our resolution, not anything special about the moonlets (they’re uncommon enough that you can pick one out from its orbit and size, but still small enough that they don’t clear a full gap in the rings).

By: Messier Tidy Upper

Messier Tidy Upper — Tue, 13 Sep 2011 16:05:39 +0000

Thankyou BA & thankyou Cassini – great image and blog item.

How large does a ring particle get before it counts as a moon or moonlet?

When do we stop counting – as Asimov once wrote and the BA seems to be alluding to in his title here, Saturn has trillions of moons including every particle in the rings!