Cassini Confirms New Moon of Saturn

pipcorona writes ""In a spectacular kick-off to its first season of prime ring viewing, which began last month, the Cassini spacecraft has confirmed earlier suspicions of an unseen moon hidden in a gap in Saturn's outer A ring. A new image and movie show the new moon and the waves it raises in the surrounding ring material."

Not a movie!

[CypherXero]

It's not a movie! Geez! It's an animated GIF image!

Re:So everythings a moon now?

[Daedalus-Ubergeek]

I do believe our own moon is named Luna, which would be where you get the word "Lunar", although you rarely ever hear anybody call the moon by its actual name.

Images!

[Roland Piguepaille]

Cool images and data:
Map and Images of Titan [arizona.edu] from Hubble Space Telescope
Nasa Titan Photojournal [nasa.gov]
Saturnian Satellite Fact Sheet [nasa.gov]
Phoebe [space.com] best image so far, from Voyager2 in 1981!

Re:So everythings a moon now?

[ag0ny]

Well, at least in Spanish-speaking countries we always call it Luna.

Re:So everythings a moon now?

[Anonymous Coward]

Earth actually has multiple moons apart from just 'The Moon', our second largest moon is Cruithne (5km across). Doesn't really mean anything though.

Re:Roche limit?

[Anonymous Coward]

The Rings are inside the Roche limit, which is the point where tidal forces will destroy a satellite. However, the Roche limit assumes a liquid body. A small solid body has enough physical strength to hold itself together even inside the Roche limit.

Re:Not a movie!

[sik0fewl]

http://dictionary.reference.com/search?q=movie

Just because something doesn't use a video codec doesn't make it not a movie.

Re:So everythings a moon now?

[frakir]

Cruithne is not a moon; it is not bound by Earth gravitation. It is an asteroid (number 3753).

Re:So everythings a moon now?

[metroplex]

Actually, in all Romance Languages (those derived by latin), the Earth's moon is called something like "Luna".

• Italian: Luna
• French: Lune
• Spanish: Luna
• Portuguese: Lua
• Romanian: Luna

Re:So everythings a moon now?

[m50d]

It's an old joke, it's been posted 3 times in the thread already, and yet you still can't get the line right? That's *no* moon.

Re:In space no one can see your color?

[bcwright]

Resolution. Most space cameras work by detecting light falling on a CCD (Charge-Coupled Device); if the camera was full color, then the resolution would be cut by at least 2/3 because you'd have to devote 1/3 of the CCD to each of the primary colors. (It might be even worse than that if your imaging system wasn't 100% efficient at directing the color components to the proper pels on the CCD). You can obtain the effect of a color camera by using different lens filters and taking multiple pictures and then composing them into a single image - this is what's usually done when a color photograph is desired. By doing that you can produce an image that's exactly what you could obtain with a color camera, but at a higher resolution and without having to use a higher resolution CCD. Also, that way your pictures aren't limited to using a selection of color components that are compatible with those the human eye sees - you can use the filters to "see" parts of the spectrum outside the range that's visible to the human eye.

Re:Roche limit?

[imsabbel]

The Roche limit only works for large bodies, when you assume that the moon is only held together by its own gravity.

For very small, rocky moons, the tensile strenght of the rock itselv enabls them to exist nearer than the roche limit. Its nothing extremely longtime-stable, but otoh, the tidal forces on a small moon arent very large.

Also, the roche limit is only a contant (2.xxx*R_bigplanet or so) if the bodies have the same density. If the objects is, for example, a captured iron asteroid, its roche limit can be VERY close to a not very dense saturn.

Re:So everythings a moon now?

[cbv]

What's next? Calling the sun something stupid like "Sol"?

Just in case you're not being sarcastic, as our Solar System's planets are actually named after Roman gods, the name for our Sun would be Sol just as Earth is actually called Terra.

For a list of names, see this compilation [nineplanets.org].

Re:"Name That Moon" Contest

[CheshireCatCO]

No good. That name would be for a moon of Jupiter (as they're usually named for his various lovers). Saturnian moons are named for Titans or Titan-like gods from other pantheons.

Re:Why asymetric?

[CheshireCatCO]

You nailed it. The ring material inside the S/2005 S1's position is moving faster than the moon, so the waves that the moon excites appear ahead of the moon's present position. (That material just had a close encounter.) The other edge of the gap is orbiting more slowly, so the moon PASSES it, so the waves appear behind the moon.

I'd avoid the word "turning" because it suggests a solid object. The rings are anything but solid.

There are other ways to make asymmetries in these wakes. If the moon isn't well-centered in the gap (although it isn't clear why it wouldn't be) or has a significant orbital eccentricity, you'll get asymmetry as well.

Re:In space no one can see your color?

[CheshireCatCO]

People have already more or less addressed this, but I'll speak up anyway.

They DO send color cameras into space. After a fashion. You have surely seen the color images taken by Cassini's ISS instrument already, so you know that it is possible. To do this, they put various filters in place and expose the CCD to take the image. The colors are then combined (with extreme love and care to get accurate color, in many cases) to make a color image. However, this clearly takes at least three times the exposure time that a single black and white image through a clear filter does. (Actually, more than that. Each filter blocks a lot of the light, so you tend to expose for longer than you would for a simple clear filter in order to get your signal to noise down.) So for a lot of science, when color isn't expected to be very important anyway (like for discovering a moon), you just use the clear filter.

Re:So everythings a moon now?

[trongey]

I do believe our own moon is named Luna...

Actually, our moon doesn't technically seem to be named anything. The International Astronomical Union (IAU), which many people consider to be the authority on such matters, doesn't seem to have any documents that specify what our moon's name is. Some of their documents use the name Moon with a capital M (eg. "Report of the IAU/IAG Working Group on Cartographic Cordinates and Rotational Elements of the Planets and Satellites: 2000" http://astrogeology.usgs.gov/Projects/ISPRS/PREPRI NTS/index_preprints.html [usgs.gov]), and I've read that they recommend the use of the name Moon.