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Rings Discovered Around a Moon for the First Time

Soulskill posted more than 6 years ago | from the chip-off-the-old-block dept.

Space 144

Riding with Robots writes "It turns out that one of the Ringed Planet's moons has rings of its own. The robotic spacecraft Cassini at Saturn has discovered that the icy moon Rhea is orbited by an extensive debris field and at least one ring, the first such system found. 'Many years ago we thought Saturn was the only planet with rings,' said one mission scientist. 'Now we may have a moon of Saturn that is a miniature version of its even more elaborately decorated parent.'"

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144 comments

star wars (0, Redundant)

Anonymous Coward | more than 6 years ago | (#22671130)

that's no moon ...

Re:star wars (2, Funny)

Anonymous Coward | more than 6 years ago | (#22671748)

No, it is not. However, circumference / pi = dia-Rhea.

Re:star wars (1)

marafa (745042) | more than 6 years ago | (#22672876)

how come that is redundant? its a reference to the death star for crying out loud!

pff (5, Funny)

McGiraf (196030) | more than 6 years ago | (#22671136)

Wake me up when they find a moon orbiting a ring.

Re:pff (1)

User 956 (568564) | more than 6 years ago | (#22671166)

Wake me up when they find a moon orbiting a ring.

That's no moon. (And that's no ring. It's a debris field.)

Re:pff (2, Interesting)

Brian Gordon (987471) | more than 6 years ago | (#22671236)

It might not even be a ring at all..

Due to a decrease in the number of electrons detected by NASA's Cassini spacecraft on either side of the moon, scientists suggest that rings are the likeliest cause of these electrons being blocked before they reach Cassini.
Not very convincing.

Re:pff (2, Flamebait)

Brian Gordon (987471) | more than 6 years ago | (#22671220)

It's amazing just how much fascinating data these deep solar system probes have gathered. Some are even out of the solar system testing interstellar space. And how many trillions have been spent uselessly collecting dust on Mars? More solar probes please!

It's called a SATELLITE, not a "moon." (2, Informative)

Anonymous Coward | more than 6 years ago | (#22671834)

There is a reason that we have a word, satellite. A satellite orbits a planet.
There is a reason that we have a word, moon. The moon is a satellite that orbits the earth.
 
However, the converse is NOT true: A satellite is a moon that orbits the earth.
 
  QED

Re:It's called a SATELLITE, not a "moon." (1)

McGiraf (196030) | more than 6 years ago | (#22673050)

The moon is a satellite of the earth.

Natural satellites of planets are moons.

Sheesh

Re:pff (1)

eln (21727) | more than 6 years ago | (#22672296)

Trillions spent collecting dust on Mars? Seriously? I doubt NASA has even managed to spend multiple trillions of dollars in its entire history, much less on any Mars missions. The Mars rovers were built, launched, and operated (for the first 90 days anyway) for $820 million. I seriously doubt the additional operating costs up to this point are anywhere near a trillion dollars, unless they've been paying their engineers several billion dollars each per year, in which case I want that job.

Re:pff (1)

siddesu (698447) | more than 6 years ago | (#22671276)

all the moons of Saturn obrit a ring in their own twisted way ;)

Re:pff (1)

McGiraf (196030) | more than 6 years ago | (#22671322)

damn! I was having a nice dream.

Re:pff (0)

Anonymous Coward | more than 6 years ago | (#22671654)

Brilliant :) You sir, are an artist.

Re:pff (1)

mcpkaaos (449561) | more than 6 years ago | (#22671672)

Wake me up when they find a moon orbiting a ring.

March 13, 1781 [wikipedia.org]

space crud in crud's shoes (1)

Clueless Nick (883532) | more than 6 years ago | (#22672962)

What is the smallest size of space rock that can aspire to have some space debris orbiting around it, either as ring or as rock?

This no troll, just curious question.

Re:space crud in crud's shoes (1)

McGiraf (196030) | more than 6 years ago | (#22673060)

Well I guest that two pebbles or even two dust particle could orbit each other.

Thats no moons (-1, Offtopic)

Anonymous Coward | more than 6 years ago | (#22671146)

it's a ring of cum around the hole in your ass.

Pre-emptive comment (2, Funny)

Jugalator (259273) | more than 6 years ago | (#22671148)

Pre-emptive semi-funny comment involving the Goatse guy, a ring, and mooning.

Re:Pre-emptive comment (1)

Kinky Bass Junk (880011) | more than 6 years ago | (#22671436)

Pre-emptive semi-funny comment involving the Goatse guy, a ring, and mooning.
Don't get upset because you couldn't think of a witty remark.

Re:Pre-emptive comment (0, Redundant)

SlashWombat (1227578) | more than 6 years ago | (#22671558)

Are there rings around Uranus? How about Ma's?

Re:Pre-emptive comment (0)

Anonymous Coward | more than 6 years ago | (#22671832)

At least the headline wasn't "SLASHDOT SUX0Z" followed up by some ASCII art

Obligatory (0)

Anonymous Coward | more than 6 years ago | (#22671162)

That's no ring!

Dumb question: Why are they 2 dimensional? (5, Interesting)

guanxi (216397) | more than 6 years ago | (#22671180)

You get used to seeing them and maybe don't question it, but why do so many structures in 'outer space' -- low gravity, three-dimensional space -- take on essentially two-dimensional forms? Consider rings around planets, planetary systems around stars, and galaxies, at least. They are all flat discs.

I asked an astrophysicist I know and she said, 'that's the way the math works out'. Ah, thanks. Maybe someone here can be more enlightening.

Disclaimer: For all you nitpickers, I know there are more than three dimensions, and that the structures are not truly two-dimensional. Unless string theory applies here, I think we can leave those facts out of the discussion.

Re:Dumb question: Why are they 2 dimensional? (1)

DragonWriter (970822) | more than 6 years ago | (#22671240)

You get used to seeing them and maybe don't question it, but why do so many structures in 'outer space' -- low gravity, three-dimensional space -- take on essentially two-dimensional forms? Consider rings around planets, planetary systems around stars, and galaxies, at least. They are all flat discs.


I think it boils down to spin and gravity.

Re:Dumb question: Why are they 2 dimensional? (1, Insightful)

Anonymous Coward | more than 6 years ago | (#22671282)

Conservation of angular momentum.

Re:Dumb question: Why are they 2 dimensional? (4, Informative)

QuantumG (50515) | more than 6 years ago | (#22671308)

http://www.faqs.org/faqs/astronomy/faq/part4/section-15.html [faqs.org]

Will answer your question much better than I could.

Re:Dumb question: Why are they 2 dimensional? (1)

guanxi (216397) | more than 6 years ago | (#22672742)

Doh! I should have read the FAQ! It's been a long time since I checked out Usenet FAQs; what a great resource (and explanation).

Re:Dumb question: Why are they 2 dimensional? (1)

kesuki (321456) | more than 6 years ago | (#22671632)

despite what many have said...

it really boils down to how does a galaxy form. compare a true 3-d object and nebula very round, nothing attracting anything to the middle. so nothing coalesces into planets, stars, and asteroids.

the trick here is the spiral galaxies all have a VERY large gravity source in the center. everything without sufficient angular momentum gets sucked in. so things in odd orbits, that aren't on a narrow plane... get sucked in to the middle. EVEN way out here on the edge of the spiral galaxy, things not on the plane of central gravity mass are imbalanced, and get sucked in, so stuff stays flat... round objects, stars, planets, gas giants form. even asteroid belts, even debris belts far outside the solar system. it all happened way before our star was even finished forming, when the super galaxies that formed all the heavy metals (uranium etc) dissolved into nebula and spiral and normal galaxies, and 'dark matter'

we're in spiral galaxy, so things tend to form in rings and other flat things. if you slowed something down, or put it in an odd orbit it would eventually reach the middle of the galaxy just from gravity. no angular momentum, and it's gone. the closer it gets the faster it goes. I'm not so sure about how non spiral galaxies are, but then the science on non spiral galaxies are far less, we basically only get the stars to look at, and the black holes if any...

Re:Dumb question: Why are they 2 dimensional? (4, Informative)

CheshireCatCO (185193) | more than 6 years ago | (#22671800)

Whoever told you this was wrong.

Inclination of the orbit has nothing to do with the total angular moment. h = sqrt(G M a (1-e^2)), where h is the specific angular moment, G is Newton's constant, a is the semi-major axis of the orbit, M is the central body's mass (I'm assuming a point source), and e is the eccentricity. Note the lack of the inclination in there. If you think about it, it *has* to be ascent: unlike e and a, the reference plane (and therefore I) is really arbitrary. There are often better choices than others, but they're in no way absolute.

The existence (especially the high frequency of) elliptical and irregular galaxies supports this idea that disks aren't inherently required, even if they are very common.

Our solar system's flatness and the rings or Saturn is also entirely unrelated to the galaxy's shape. If it where related, you'd expect the solar system's plane to be the same as the galaxy (it isn't: prove it to yourself and look at the line of the planets in the night sky and compare it to the line that the galaxy makes). Likewise, Saturn's rings are tilted relative to the ecliptic plane by 26 degrees so that they line in Saturn's equatorial plane.

Why are things flat? Collisions. Collisions average out velocities so they tend to a single plane. (How flat you get depends on collision frequency and any pressure support.)

Re:Dumb question: Why are they 2 dimensional? (1)

Tablizer (95088) | more than 6 years ago | (#22673016)

The existence (especially the high frequency of) elliptical and irregular galaxies supports this idea that disks aren't inherently required, even if they are very common.

But its mostly older galaxies without much dust, plasma, and debris that take such form. In other words, elliptical (roundish) galaxies have little or no friction or collisions among stars. The stars don't interact very often (with each other or with diminishing plasma and dust). The fact that most elliptical galaxies are "cleaner" than spirals is evidence for this.

Also, the average width of the particles in Saturn's rings in proportion to the space between them is much much larger than the ratio of the star sizes to their separation in older galaxies. Models suggest that ring particles can and do collide often.

Our solar system's flatness and the rings or Saturn is also entirely unrelated to the galaxy's shape.

That's because the collapsing solar disk's average momentum may have been shaped by forces stronger than the galaxy's movement, such as a nearby supernova explosion soon before collapse of the solar disk. Such explosions are often oblique or bipolar in shape, meaning they may press on one side of a plasma cloud more than another. Plus, there's lots of nearby stars in formation clusters giving unpredictable gravity kicks.
   

round galaxies continued (1)

Tablizer (95088) | more than 6 years ago | (#22673096)

But its mostly older galaxies without much dust, plasma, and debris that take such [round] form.

I should clarify this a bit. It begs the question of *how* they got semi-spherical to begin with. Most medium-to-large galaxies that we see are thought to have been involved in a couple of collisions and mergers over the years. If two dusty/gassy galaxies collide, the dust and gas will be subject to the disk-forming forces described earlier and pull or form the stars with them into a disk.

The older a galaxy gets, the less unbound gas and dust it will have because it eventually gets turned into or sucked into low-activity stars and black holes. Plus, new gas/dust is not generated as much from star deaths because there are less new stars over time. Over time what is left is small orange stars that have a long life and don't barf out much when their life ends, or neutron stars and black-holes which are pretty much done exploding. Space cleans itself of gas/dust over time via this entropy. Elliptical galaxies appear orange-yellow compared to spirals (blue-white) because of the population of these older-style stars: no clouds means no more big bright short-lived blue/white stars.

If two older galaxies collide, then there is less gas and dust to force it into a disk shape. It will thus more likely to be an elliptical (spheroid) galaxy.

The collision does seem to generate a short period of new star formation as plasma collides, but not enough to disk-ify the galaxy. This may be why such galaxies are elliptical (slightly flat) instead of fully spheroid. They did have a short period of disk-ifying influence upon merge.

(Of course, this theory could be wrong, but its a model that makes sense: less dust, less flat.)
     

Re:Dumb question: Why are they 2 dimensional? (4, Informative)

CheshireCatCO (185193) | more than 6 years ago | (#22671762)

It's not how the math works out, it's collisions. When inelastic bodies collide, their post-collision velocities tend to be nearer the (mass-weighted) average of the original velocities. For bodies orbiting a planet, the average motion is generally in the equatorial plane. Thus, for rings (or gas disks around a variety of astronomical bodies), you get flattened features. Saturn's main rings (C, B, and A) are so optically think (think "dense" if you will) that they're very, very flat. Measurements suggest that the B and A rings may be as little as a few meters thick because of all the collisions.

Re:Dumb question: Why are they 2 dimensional? (4, Informative)

AstrumPreliator (708436) | more than 6 years ago | (#22671768)

IANAA (I am not an astrophysicist) but from the physics and astrophysics classes I've taken I can venture a guess. Of course I may be wrong so feel free to correct me if I am.

When interstellar gas contracts to form a solar system it has a certain angular momentum. Now let's assume it has a counter-clockwise rotation about the z-axis as well as a counter-clockwise rotation about the x-axis. Then really it has a counter-clockwise rotation in a plane which intersects the origin at 45 degrees between the x-axis and z-axis. Okay I think I totally screwed that example up... It's too late at night to think in 3-dimensions I think ;). Anyway, the point is you're going to get rotation in a plane. So when the solar system begins to take shape this would be the plane in which it rotates. Planets form in a similar fashion to a solar system, so the spin of the planet would be in a plane and hence the debris which is caught in the planet's gravity would similarly rotate in this plane.

Of course this is all theory on how solar systems/planets form, but to my understanding this is why. I'm sure the explanation for a galaxy would be very similar. At least this is how I understand it to be.

Re:Dumb question: Why are they 2 dimensional? (1)

CheshireCatCO (185193) | more than 6 years ago | (#22671816)

You nearly nailed it. :-D All you need to throw in there is how collisions average velocities/orbits and you'll be competing for my job. ;-)

Re:Dumb question: Why are they 2 dimensional? (1)

Urza9814 (883915) | more than 6 years ago | (#22671854)

To put it as simply as possible: Because things can't spin in three dimensions.

Re:Dumb question: Why are they 2 dimensional? (5, Funny)

Tablizer (95088) | more than 6 years ago | (#22671870)

and maybe don't question it, but why do so many structures in 'outer space' -- low gravity, three-dimensional space -- take on essentially two-dimensional forms? Consider rings around planets, planetary systems around stars, and galaxies, at least. They are all flat discs.

The Flying Spaghetti Monster [wordpress.com] makes flat plate-like shapes because spaghetti likes to rest on plates. See, it all falls into place logically.
             

Re:Dumb question: Why are they 2 dimensional? (1)

guanxi (216397) | more than 6 years ago | (#22672986)

In all seriousness, I finally grocked the answer to my question over a bowl of spaghetti. I will leave irrefutable proofs to others ...

Re:Dumb question: Why are they 2 dimensional? (2)

laejoh (648921) | more than 6 years ago | (#22672994)

Do I really need to mention [wikipedia.org] more?

His noodly appendage touches us all in ways we cannot even imagine!

Re:Dumb question: Why are they 2 dimensional? (1)

mark_hill97 (897586) | more than 6 years ago | (#22672074)

Take a mass and put it onto a string, now attempt to get it to spin in three-dimensions. You should be finding that quite impossible, rotational forces cause it to all to line up into a single plane.
You should also notice that rings appear around the middle of the planets, directly in between the two poles. This is because this is where the spin is, so your rotation is going to go to the outermost point it can get to but being unable to escape the gravity us stuck at this widest point.

Re:Dumb question: Why are they 2 dimensional? (5, Informative)

Minwee (522556) | more than 6 years ago | (#22672100)

Why do so many structures in 'outer space' -- low gravity, three-dimensional space -- take on essentially two-dimensional forms? Consider rings around planets, planetary systems around stars, and galaxies, at least. They are all flat discs.

Try this some day. Take a bit of rope with a ball at the end of it. A tennis ball will do nicely. Bowling balls are just asking for trouble. Now hold the end of the rope and spin around as fast as you can. You now represent a planet, the tennis ball represents a part of a ring and the rope represents gravity. Try not to get dizzy and fall down. Falling down and throwing up doesn't represent anything in astronomy. That's engineering.

Notice that the ball spins in a more or less flat circle. Inertia carries it forwards and the rope pulls it towards you. There really isn't any force pushing it up or down, so it will naturally orbit in a flat plane.

Okay, whoopdie doo. I just told you that a circle is flat. What you're really asking is why millions of little rocks in a ring will all orbit in the same plane instead of going off and doing their own thing, each orbiting in slightly different directions forming a huge cloud.

Are you still spinning that ball around? Good. Now, pick up another one in your other hand and start spinning it as well. Chances are that both balls are spinning at the same speed at opposite ends of the same circle, so everything is fine. Here's where the demonstration gets a bit tricky. You need to unhinge your arms so that you can spin both balls at different angles and slightly different speeds. Since I don't want you to need to undergo major surgery in the name of physics I'll just skip to the ending and tell you what would happen if you could do that.

The balls are going to hit each other. It may not happen right away, but if you have objects moving in intersecting orbits it _will_ happen. If you had a few million balls all spinning around at different angles you would have a better representation of the rings we're talking about with a lot more collisions, but that requires a whole lot of rope and we don't have that much.

Now we can get back to the original question. Why do all these rocks form flat rings? I could tell you that that's the only way that they won't hit each other, but that doesn't answer the question of how they got there. Suppose that you took about a million little rocks and put them all in random orbits around a planet. At the start they would form a spherical cloud around it -- A ha! A three dimensional structure, just like you were asking for. But the question is "How long can it last?"

All of those rocks are going to start hitting each other, and every time they do they're going to transfer momentum. With enough objects traveling in enough different orbits that's going to happen a _lot_. Do you want to know how much? Look up at the moon some time and count the craters. Back when the solar system was young and not quite so flat, things were smashing into one another all the time. Every time they collided they scrupulously obeyed the law of conservation of momentum and shifted into different directions. Eventually the total momentum of that spherical cloud started to average out and more and more rocks found themselves orbiting in the same flat plane. Why did that happen? Simply because those were the ones that got hit less. Like your friend the astrophysicist said, "That's the way the math works out". It's all about averages, and when you're dealing with millions of rocks smacking into one another over billions of years, that's what matters.

But if we're dealing with _averages_ and _statistics_, why is everything so perfectly flat? Why are all of the planets, moons and rings all in the same plane, and why do all of the billions of stars in the Galaxy move in the same flat orbits?

The simple answers to those questions are "It's not", "They don't" and "That doesn't happen". While the planets all move in roughly the same plane, their orbits are all inclined by anywhere up to 17 degrees. The only reason that they are that close and all orbit in the same direction is that they were all made up of the same big mess of spinning gas and dust that the rest of the solar system was made up of. That average momentum we were talking about was the same for all of the planets back when they formed. Planets themselves are generally spinning around 20 to 30 degrees away from their orbits, and what about those big, flat Spiral Galaxies? If you look closely they also have a spherical halo of stars that just didn't go for being in the spiral. It's all about averages.

On average the planets all fall into the same flat plane. On average the stars in a Spiral galaxy (But not an elliptical or irregular galaxy) are all near the spiral arms. On average the junk orbiting a big planet falls into a flat ring. There are always exceptions, just because probability hasn't caught up with them yet.

Does that help any, or am I just waving my arms about and looking excited?

Re:Dumb question: Why are they 2 dimensional? (1)

ghostdancer (72944) | more than 6 years ago | (#22672680)

This is one of those moment where reading at Slashdot actually gets you to learn something.

Cool post.

Re:Dumb question: Why are they 2 dimensional? (1)

sapphire wyvern (1153271) | more than 6 years ago | (#22672790)

Good explanation. Most illuminating!

For extra credit: why does the universe have all this angular momentum to begin with? Where did that come from? Why doesn't a proto-solar system just collapse into a sphere?

Re:Dumb question: Why are they 2 dimensional? (1)

guanxi (216397) | more than 6 years ago | (#22672814)

It's a great description, but I think the heart of the matter still needs clarity:

I could see that, over billions of years, any collision that could happen would happen, and it would eliminate intersecting orbits (as well as average out the objects' momentum). That wasn't why I posted.

But those two balls only hit each other (assuming the ropes magically don't cross) if the ropes are the same length. If we could tip Jupiter's orbit, no matter what angle of inclination we used, it would not collide with other planets. It does not need to be in a plane for that purpose.

The hand-waving -- and the reason for my question -- is why a sphere (or some 3D system) resolves so often into a plane, I get the sense that it's the result of the momentum averaging out, but it's not quite clear. Heck, why not two non-intersecting discs on different planes, or ten? Maybe it's one of those issues for which there is no substitute for the math -- not even a /. post.

Thanks.

Re:Dumb question: Why are they 2 dimensional? (1)

guanxi (216397) | more than 6 years ago | (#22673034)

Nevermind, I understand it now ... for others still unsure after Minwee's clever explanation, I recommend the FAQ linked further up the thread. Thanks again Minwee.

Re:Dumb question: Why are they 2 dimensional? (1)

Whiteox (919863) | more than 6 years ago | (#22673076)

The force of gravity is 'directional', as all matter of the galaxy is already on the same plane. So as the solar system matures further, rings and moons will eventually be forced into the same plane.

A simple system like 2 masses rotating around each other has a greater gravitational attraction in one plane. A third mass initially rotating around this simple system in a different plane, will eventually force this triad into a plane common to all 3 masses.

Re:Dumb question: Why are they 2 dimensional? (1)

s74ng3r (963541) | more than 6 years ago | (#22673068)

Tolkien was right. One ring to rule them all.

No moon (-1, Flamebait)

Nimey (114278) | more than 6 years ago | (#22671184)

Sure as shootin', the usual slashtards will make tired old jokes about that being no moon, tag the article as such, &c. Perhaps they even think they're being funny.

And you? (-1, Offtopic)

Mantaar (1139339) | more than 6 years ago | (#22671268)

And you? You're thinking what now? Are you insightful? Hardly... Want to get modded as such? Try harder... I decided not to spend my modpoints on you

Get over with it: memes are an essential part of /. culture. That's the way things are here. Not all of them are funny to you, but some of them are worth it. Another meme is to use a useless meme in the first post. Well, you even overlooked that one this time, since the first post in this article actually is that tired old meme.

Why didn't you see it? Well surely because you don't browse at -1. See, that's what moderation is good for. It works - far better than on digg or reddit IMHO. Use it, and those pesky 'slashtards' won't actually bother you all that much.

Now, stop grunting and go say something useful.

Rhea is her name... (1, Funny)

Anonymous Coward | more than 6 years ago | (#22671188)

Icy and loves rings? Sounds like my ex-wife.

Photo. (5, Informative)

palegray.net (1195047) | more than 6 years ago | (#22671208)

Here's a photo of Rhea [nasa.gov] from nasa.gov. Gives some nice background information on the moon as well.

Wonderful, but... (-1, Flamebait)

Anonymous Coward | more than 6 years ago | (#22671430)

How do I get Quake 3 to run on Linux???

Re:Wonderful, but... (1)

QuantumG (50515) | more than 6 years ago | (#22671512)

dont. apt-get install openarena

Funny timing (3, Interesting)

Brad1138 (590148) | more than 6 years ago | (#22671226)

Just last week my son said something that made me wonder, "could we put a satellite in orbit around our moon"?

Re:Funny timing (4, Interesting)

Mantaar (1139339) | more than 6 years ago | (#22671326)

Yes of course we could. If you download Celestia [celestia.org] you can see all sorts of interesting things in space.
Now, my version is heavily modded (and it's the alpha version), but I can see Apollo still orbiting good ol' Moon in Celestia. And witness a nice dawn together with Apollo. *sigh* it's a pity that you go through that military drill to become an astronaut. I surely would like to be one.

Essentially, that's the same as putting a satellite around Earth, as Earth orbits Sun like Moon orbits Earth.

What's even more interesting: you could put a spacecraft in the Lagrange-point between Earth and Moon, so it wouldn't move - well with respect to Earth and Moon, of course.

Re:Funny timing (1)

JonathanR (852748) | more than 6 years ago | (#22671380)

*sigh* it's a pity that you go through that military drill to become an astronaut. I surely would like to be one.
I hear there's an opening on a Mars mission... Given NASA funding shortages, they might be ok to dispense with all the military drill for that one.

Re:Funny timing (1)

glavenoid (636808) | more than 6 years ago | (#22671562)

*sigh* it's a pity that you go through that military drill to become an astronaut. I surely would like to be one.

I hear there's an opening on a Mars mission... Given NASA funding shortages, they might be ok to dispense with all the military drill for that one.

Or, if you're young enough, mmm, just wait about 15-20 years (boo-HEY!). Commercial space flight is inevitable in the near future. Of course, trained astronauts will probably get first dibs, but you never know...

Re:Funny timing (1)

ScrewMaster (602015) | more than 6 years ago | (#22671600)

Well, given the recent talk about making the trip a one-way [slashdot.org] proposition, I'd say that they would probably dispense with a lot of requirements. Why waste money on a highly-paid, highly-trained astronaut he's at best a disposable commodity? Just pick some joe like the GP who really wants to get into space and ship him out.

I mean, technically you don't have to tell him he's not coming back.

Re:Funny timing (1)

peragrin (659227) | more than 6 years ago | (#22671662)

he will notice the lag in his internet connection though.

of course Nasa could always higher a comcast help desk monkey to put him on hold for a while.

Re:Funny timing (1)

JonathanR (852748) | more than 6 years ago | (#22672208)

of course Nasa could always higher a comcast help desk monkey
I thought we'd already put monkeys into space [wikipedia.org]

Re:Funny timing (1)

glavenoid (636808) | more than 6 years ago | (#22671534)

What's even more interesting: you could put a spacecraft in the Lagrange-point between Earth and Moon, so it wouldn't move - well with respect to Earth and Moon, of course

Thank You!! Lagrangian Point - that's the term I've been trying to remember for the longest time. Incidentally, if a massive enough object were to pass through this point relative to the earth and the moon, the moon would fall into the earth. Although the likelihood of such an occurrence is, er, astronomical...

Re:Funny timing (2, Insightful)

AikonMGB (1013995) | more than 6 years ago | (#22671940)

Its too bad L1-3 are unstable.. you'll still need small maneuvering thrusters/attitude gyros etc. to keep your craft from straying too far from the equilibrium point. L4 and L5 are dynamically stable, but there's also a lot of other cruft just lying around there that you'd have to shield against.

But yes, Lagrange points are awesome and we need to exploit them more!

Aikon-

From the Earth To the Moon (2, Insightful)

Timothy Chu (2263) | more than 6 years ago | (#22671994)

All this talk about orbiting the moon and the Lagrange point reminded me of Jules Verne's "From the Earth To The Moon", a surprisingly accurate description of lunar travel written 140 years ago. I only wish space travel were as simple as he described.

Re:Funny timing (1)

Mycroft_VIII (572950) | more than 6 years ago | (#22672400)

Celestia.org is a dead domain. Just list of 'searches' based on the word celestia and an offer to sell the domain name.
perhaps you meant http://www.shatters.net/celestia/ [shatters.net] ?
      At least following the first google link there looks like the right page, and links to a sourceforge project named celestia.

Mycroft

Re:Funny timing (1)

creimer (824291) | more than 6 years ago | (#22671584)

No, no, no. The moon is good for slamming stuff into and leaving garbage behind. Besides, why have a satellite around the moon when the weather never changes?

Re:Funny timing (2, Informative)

AikonMGB (1013995) | more than 6 years ago | (#22671914)

Yes. In fact, there's already a mission planned: the Lunar Reconnaissance Orbiter [nasa.gov] (LRO). Set for launch later this calendar year, the LRO will be put into a low polar lunar orbit for about 1 year. Among its objectives are the creation of high-resolution lunar maps (it is equipped with a laser altimeter), seek suitable landing ellipses for future craft, and search for evidence of water ice and other resources.

Aikon-

Re:Funny timing (1)

AikonMGB (1013995) | more than 6 years ago | (#22671924)

Forgot to mention: The LRO orbital period is roughly 2 hours.

Aikon-

Wow. (3, Interesting)

Aegis Runestone (1248876) | more than 6 years ago | (#22671230)

That's really cool. I was so into the planets when I was young. Loved the Voyager missions (even made a model of the probe out of Contrux... and it was accurate too), and watched as many Nova specials about the Voyager missions as possible. That kid is not dead, he's just taken a place inside of me. I keep an occasional glance at the Cassini mission, just like the Galileo mission to Jupiter.

This is, indeed, a surprise discovery and hopefully there might be more material to study concerning this ring-type.

On a somewhat related-note: It is ironic that this moon has a ring whereas two moons hang out in Saturn's outer rings (they are called the Shepherd Moons).

Re:Wow. (1)

MrKneebone (911473) | more than 6 years ago | (#22671356)

How does the rotation of a planet affect it's orbiting bodies? over time do they drift toward the equator? I thought that i'd heard years ago that there was a moon (or moons) with rings. Is this really new news, or am i mistaken?

Re:Wow. (1)

CheshireCatCO (185193) | more than 6 years ago | (#22671740)

I know of no moon with rings, but I may be missing an old press-release somewhere. :-)

If the central body is spherical symmetrical, its rotation is entirely irrelevant. If it has any asymmetry, things get more interesting. A lone satellite (or satellites that don't interact significantly) will have their orbits precess in space, but they won't tend toward the equator. However, if you have interacting satellites, all sorts of things can happen. In the case of rings/disks, collisions betweens bodies averages out their velocities/orbits, which usually puts them in the planet's equatorial plane.

Re:Wow. (1)

CheshireCatCO (185193) | more than 6 years ago | (#22671716)

Depending on your definition of "in the rings", there are around 5 moons (shepherds all) already known: Pan (Encke gap), Daphnis (Keeler gap), Atlas (Roche gap), and Prometheus and Pandora (shepherding the F ring). However, I'd be careful calling this the outer rings: the E and G rings are exterior to the F ring. :-)

Re:Wow. (1)

Aegis Runestone (1248876) | more than 6 years ago | (#22671974)

Ah, thank you on correction.

That's no moon... (1)

silencer51 (770736) | more than 6 years ago | (#22671310)

...it's a ringed moon(TM)!



(i'm so sorry)

Obviously... (1)

tjstork (137384) | more than 6 years ago | (#22671312)

This proves that the global warming skeptics are horribly right. Global warming is being caused by disturbances in the solar system. However, it turns out that this is actually an invading Cylon fleet of six basestars, and the wreckage we see, is sadly, the Battlestar Galactica.

We're all DOOMED.

Re:Obviously... (1)

rebelcan (918087) | more than 6 years ago | (#22671842)

DOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOMED! </Bender>

Damnit, it's supposed to be in-your-face-Bender-style-yelling, Slashdot, stop complaining.

uh? (1)

nobey (911370) | more than 6 years ago | (#22671424)

I'm pretty sure most planets have a ring of debris around them. Uranus has a very dim ring. Earth has a ring but it isn't visible with out special gear.

Re:uh? (1)

djradon (105400) | more than 6 years ago | (#22672676)

I wonder if there's a fictional precedent (image or prose) for a ringed moon?

Can we make some rings around our own moon? (2, Funny)

LionKimbro (200000) | more than 6 years ago | (#22671428)

Perhaps there's something relatively simple we can do, to add rings around our moon. Like shooting a missle at an asteroid in the asteroid belt, *just so,* or perhaps the next time a comet comes by.

It'd be a really nice decoration.

Re:Can we make some rings around our own moon? (1)

glavenoid (636808) | more than 6 years ago | (#22671734)

Please, you need to think your plan through a little more. Funding problems and whatnot. "Enjoy Pepsi - Choice of the Lunar Generation"

Re:Can we make some rings around our own moon? (1)

garompeta (1068578) | more than 6 years ago | (#22672110)

Well, i guess it will happen sooner or later with all the space junk orbiting around us...

obligatory (1)

circletimessquare (444983) | more than 6 years ago | (#22671462)

that's no ring...

Re:obligatory (0)

Anonymous Coward | more than 6 years ago | (#22671970)

and that's no moon.

Maybe Rings/Dusty Halo (3, Informative)

CheshireCatCO (185193) | more than 6 years ago | (#22671496)

Despite JPL's press-release filled with certainty, this is not a definite detection. The imaging instrument has not seen any ring or halo around Rhea in spite having looked. This does not prove that the putative ring is not there (more observations are planned), but it is contrary evidence and suggests we start asking ourselves what else might cause these data.

Does this mean (3, Funny)

zakeria (1031430) | more than 6 years ago | (#22671514)

they got engaged ?

Re:Does this mean (1)

nacule (1249808) | more than 6 years ago | (#22671760)

...first the engagement ring, then the wedding ring, and then suffering....

Yeah, in mythology they were husband and wife (5, Interesting)

dido (9125) | more than 6 years ago | (#22672438)

You joke, but Saturn's (Cronus's) wife in mythology was named Rhea. A bit of a coincidence that.

Yes but (0, Redundant)

carnalforge (1207648) | more than 6 years ago | (#22671526)

Does does it's ring have another ring too? Oh well, the more i think about it the more i'm convinced Saturn must have piercings too. Love that fetish

Please (1)

artichokesquid (1252062) | more than 6 years ago | (#22671648)

" A broad debris disk and at least one ring appear to have been detected by a suite of six instruments on Cassini specifically designed to study the atmospheres and particles around Saturn and its moons."
Please let the rings be named Dia.

Fractal astronomy! (1)

jlherren (1025754) | more than 6 years ago | (#22671650)

> Now we may have a moon of Saturn that is a miniature version of its even more elaborately decorated parent.

Cool, fractal astronomy! Does the moon's ring have rings itself?

And in next year's news... (2, Funny)

tverbeek (457094) | more than 6 years ago | (#22671674)

The next discovery will be that one of the rocks orbiting Rhea itself has a ring around it.

BrOWN RING DISCOVERED AROUND URANUS (-1, Offtopic)

Anonymous Coward | more than 6 years ago | (#22671756)

"Many years ago we thought Saturn was the only planet with rings," said mission scientist Sgt. Shaved Balls. "Now we may have the
Mark of the Brown Ring around Uranus." [doiop.com]

Aw, how cute (1)

Tablizer (95088) | more than 6 years ago | (#22671766)

the baby has a ring like the father.

Space junk? (1)

fiannaFailMan (702447) | more than 6 years ago | (#22671792)

Maybe it's space junk from an ancient civilisation.

There's a ring around the earth! (1)

erroneus (253617) | more than 6 years ago | (#22671794)

We're sending so much crap out into orbit that we've built our own ring.

That's no moon... (0, Offtopic)

blurryrunner (524305) | more than 6 years ago | (#22671824)

it's dia-Rhea?

rings + Rhea = diameter + Rhea ~= diarhea ...yeah, I said it. yeah it's missing an 'r'.

or death to rhea or die-rhea?

ok, sorry...back to the basement....

br/

Wasn't there a movie about this? (5, Funny)

rumli (1066212) | more than 6 years ago | (#22671862)

'Many years ago we thought Saturn was the only planet with rings,' said one mission scientist...
But they were all of them deceived, for another ring was made...

Explain something to me... (-1)

Anonymous Coward | more than 6 years ago | (#22671934)

How is it that we just discovered this fact regarding a spacial object so close to home, yet we supposedly know so much about what is happening in galaxies that exist much further away? The idea that we know so little about our own back yard makes me more sceptical regarding all these other "facts" that space-gazing scientists keep bringing us.

I mean come on... how can we honestly pretend to know anything about other galaxies if we can't even know the basics about our own solar system? Maybe we should focus more on our own 8 planets for a while before we prematurely run off to explore the rest of the universe?

Of course, until recently we thought we had 9 planets. The idea that we couldn't even accurately determine that little fact really makes me think that all the "facts" we've gathered regarding objects outside of our own solar system are just we-know-nothing-but-like-to-think-we-know-everything, "the Earth is flat" kind of facts.

My smell-o-scope indicates that /.ers are flinging large balls of garbage at me. :'(

Misleading (1)

Tarlus (1000874) | more than 6 years ago | (#22672106)

At first I read that as "Rings Discovered Around the Moon for the First Time."
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