NASA Discovers Giant Ring Around Saturn

caffiend666 writes with news that scientists using the Spitzer Space Telescope have discovered a very large, previously unknown ring around the planet Saturn. According to NASA, if the ring were visible to the naked eye from Earth, it would cover a patch of sky roughly twice the angular diameter of the Moon. "The new belt lies at the far reaches of the Saturnian system, with an orbit tilted 27 degrees from the main ring plane. The bulk of its material starts about six million kilometers away from the planet and extends outward roughly another 12 million kilometers. One of Saturn's farthest moons, Phoebe, circles within the newfound ring, and is likely the source of its material. Saturn's newest halo is thick, too — its vertical height is about 20 times the diameter of the planet. It would take about one billion Earths stacked together to fill the ring. ... The ring itself is tenuous, made up of a thin array of ice and dust particles. Spitzer's infrared eyes were able to spot the glow of the band's cool dust. The telescope, launched in 2003, is currently 107 million kilometers from Earth in orbit around the sun."

Re:Missed by Voyager?

[irussel]

Did you even read the articles?

quote:
JPL spokeswoman Whitney Clavin said the ring is very diffuse and doesn't reflect much visible light but the infrared Spitzer telescope was able to detect it.

"The particles are so far apart that if you were to stand in the ring, you wouldn't even know it," said Verbiscer.

Re:Esoteric Naming System

[wiredog]

IIRC, they're named in the order of discovery.

Re:Esoteric Naming System

[cwiegmann24]

I wonder if they were named in sequence (A, B, C ... ) as they were discovered, not as they lie from closest to farthest. I could understand as equipment got better, NASA was able to send spacecraft closer, etc., more rings would be identified.

Re:Angular diameter

[clone53421]

The angular diameter or apparent size of an object as seen from a given position is the âoevisual diameterâ of the object measured as an angle.

What's hard to understand about that?

It even said: It's the apparent size.

In other words, the angular size is how big something looks if you disregard how far away it is.

For instance, here is a picture of a bird silhouetted against the moon [gstatic.com]. The bird is close to the viewer (appearing large) and the moon very far away (appearing small). Although we know it's huge, the moon looks like it's nearly the same size as the bird. Their visual diameters are nearly the same.

Here's another picture of a bird silhouetted against the moon [gstatic.com]. In this one, the bird is quite far away (though nowhere near as far away as the moon), and looks small in comparison. The moon is about the same size (visual diameter) as it was in the last picture, but the visual diameter of the bird is much smaller.

Re:Saturn is polygamous

[MRe_nl]

Saturn has four main groups of rings and three fainter, narrower ring groups. These groups are separated by gaps called divisions. Close up views of Saturn's rings by the Voyager spacecrafts, which flew by them in 1980 and 1981, showed that these seven ring groups are made up of thousands of smaller rings. The exact number is not known.

The main rings are extremely thin. They stretch 70,000 kilometres from their inner to outer edge, but are only about 100 metres thick. They are made of loose ice particles in all sorts of sizes.

"They go from the size of houses down to the finest ice particles, like the snow you might ski on in Utah" says Carolyn Porco, head of Cassini's imaging team and an expert on the rings.

Voyager showed that thousands of gaps break the main rings up into ringlets that are often only a few kilometres wide. In the pictures from Cassini, it is clear that some ringlets are narrower still, maybe only half a kilometre or less.

Those pictures also show that they have very sharp edges, even though the ice particles should be bouncing off each other and blurring the edges of the rings. "It's very mysterious - they must be held sharp by some mechanism," says Porco. "In some cases it is done by moons, but with many of the edges we don't know the mechanism."

Maybe some of the questions raised by Voyager and Cassini can be answered by these new findings.

Re:Iapetus?

[agentgonzo]

Yes. The BBC article [bbc.co.uk] states that this ring is the cause of the dark matter on Iapetus. Iapetus is tidally locked to Saturn, so will always present the same side to the direction of motion in its orbit. This side is the darker side of Iapetus and it seems to fit perfectly that this is due to collisions with the particles from this ring over the eons like bugs on a cosmic windscreen.

Re:Wait a sec

[PvtVoid]

Wouldn't the moon be accreted from the ring? Why would Phoebe be shedding material?

Impacts [scientificamerican.com]. Stuff gets kicked up from Phoebe and accreted by Iapetus:

The study's authors speculate that meteoric impacts on Phoebe's dark, heavily cratered surface liberate the particles that form the ring. That assertion might explain the anomalously two-toned surface of Iapetus, a Saturnian moon inside Phoebe's orbit. The smaller particles of the Phoebe-generated ring should migrate inward, where they would eventually be swept up by Iapetus, coating the inner moon's leading face with dark material--a prediction knocked about for decades that jibes with observation. The presence of the debris ring implies that this process is ongoing.

Re:Whats funny is my initial reaction to the headl

[TheRaven64]

I can sell you an invisible ring that keeps invisible tigers away! I've been wearing mine for years and in all that time didn't see a single invisible tiger!

Re:You've perked my interest

[Anonymous Coward]

http://www.stellarium.org/

Re:Missed by Voyager?

[LateArthurDent]

Personally, I'd be more preoccupied with trying to breathe and not instantly freeze to death.

You wouldn't really instantly freeze, that's a misconception. Without being in direct contact with something, like an atmosphere, there's no heat transfer via conduction or convection. In a vacuum you only lose heat via radiation, and you know that's pretty slow, since Vacuum flasks [wikipedia.org] can keep things hot for a really long time.

So yeah, breathing would be your concern.

original source on Spitzer's web site

[lotXLIX]

Here is the original article on Spitzer's site: http://spitzer.caltech.edu/news/964-ssc2009-18-NASA-s-Spitzer-Spots-Clump-of-Swirling-Planetary-Material [caltech.edu]

Re:Well

[CrimsonAvenger]

I don't know if you could consider this is part of the ring system around Saturn due to the fact that is start around 3.7 millions miles away from the planet and stretched out to its furthest at 7.4 millions miles; I'm not an astronomer by any means but I would consider this and asteroid belt of some sort; Saturn gravitation pulled cannot be that strong holding materials that far away.

Gravitational pull by Saturn at a distance of 7.4 million miles: ~0.275 mm/s^2.

Gravitational pull by Sol at the nearest point in those rings (7.4 million miles closer than Saturn's perihelion): 0/075 mm/s^2.

So, yes, Saturn exerts almost four times more force on the particles of this new ring than the Sun does. And this assuming the most favourable case for the sun, and the least favourable for Saturn.

Re:Why no picture?

[clone53421]

Well, there's also this [nasa.gov] ... if I'm reading the description correctly, it's the Spitzer infrared picture, with an enhanced inset plus an inset photo of Saturn taken by the Hubble.

Re:Whats funny is my initial reaction to the headl

[Sulphur]

We are making one.

Re:Good thing...

[Jogar the Barbarian]

Wrong! It's yoo-RAIN-us. Think of the U as a separate syllable and you'll be fine.

Re:Missed by Voyager?

[Sheafification]

Losing heat by radiation is only slow when there's lots of stuff around you radiating back. According to this [kilty.com] humans lose between 50% and 60% of their heat from radiation. When you are floating exposed in space NONE of that heat comes back. It's not instant freezing, but it's not exactly slow either.