New ring detected around Saturn

[neufer]

New ring detected around Saturn
By Jonathan Amos Science reporter, BBC News

<<A colossal new ring has been identified around Saturn. The dusty hoop lies some 13 million km (eight million miles) from the planet, about 50 times more distant than the other rings and in a different plane. Scientists tell the journal Nature that the tenuous ring is probably made up of debris kicked off Saturn's moon Phoebe by small impacts.

Graphic of the Saturn system and new ring


They think this dust then migrates towards the planet where it is picked up by another Saturnian moon, Iapetus. The discovery would appear to resolve a longstanding mystery in planetary science: why the walnut-shaped Iapetus has a two-tone complexion, with one side of the moon significantly darker than the other. "It has essentially a head-on collision. The particles smack Iapetus like bugs on a windshield," said Anne Verbiscer from the University of Virginia, US.

Observations of the material coating the dark face of Iapetus indicate it has a similar composition to the surface material on Phoebe.

The scale of the new ring feature is astonishing. Nothing like it has been seen elsewhere in the Solar System.

The more easily visible outlier in Saturn's famous bands of ice and dust is its E-ring, which encompasses the orbit of the moon Enceladus. This circles the planet at a distance of just 240,000km. The newly identified torus is not only much broader and further out, it is also tilted at an angle of 27 degrees to the plane on which the more traditional rings sit. This in itself strongly links the ring's origin to Phoebe, which also takes a highly inclined path around Saturn.

Scientists suspected the ring might be present and had the perfect tool in the Spitzer space telescope to confirm it.

The US space agency observatory is well suited to picking up the infrared signal expected from cold grains of dust about 10 microns (millionths of a metre) in size. The ring would probably have a range of particle sizes - some bigger than this, and some smaller. Modelling indicates the pressure of sunlight would push the smallest of these grains towards the orbit of Iapetus, which is circling Saturn at a distance of 3.5 million km.

"The particles are very, very tiny, so the ring is very, very tenuous; and actually if you were standing in the ring itself, you wouldn't even know it," Dr Verbiscer told BBC News. "In a cubic km of space, there are all of 10-20 particles." Indeed, so feeble is the ring that scientists have calculated that if all the material were gathered up, it would fill a crater on Phoebe no more than a kilometre across.

The moon is certainly a credible source for the dust. It is heavily pockmarked. It is clear that throughout its history, Phoebe has been hit many, many times by space rocks and clumps of ice.>>

[neufer]

<<The Spitzer Space Telescope has spied an enormous ring around Saturn, the largest and farthest distant band around this ringed world. Just how big is this ring? "If you had infrared eyes like Spitzer," said Anne Verbiscer, research astronomer at the University of Virginia, Charlottesville, "from Earth, it would look like one full moon on either side of Saturn." That's incredibly huge! The bulk of its material starts about six million kilometers (3.7 million miles) away from the planet and extends outward roughly another 12 million kilometers (7.4 million miles). A billion Earths could fit in the volume of space this ring occupies.

So, why hasn't this gigantic structure been detected previously?

"It is very, very faint; extremely tenuous," Verbiscer told Universe Today. "If you were standing inside the ring you wouldn't even know it. In a cubic kilometer of space there are only 10-20 particles. The particles are about the same size as fog particles, but they are very spread out. We're just looking at the thermal emissions these little particles are giving off; we're not looking at reflected sunlight at all in the observations we did with Spitzer. That's what makes Spitzer the perfect instrument to use to try and find such a dust structure. This ring is completely analogous to debris disks around other stars that Spitzer has observed."

The research team didn't just stumble upon this ring; they were searching for it. The team includes Verbiscer, Douglas Hamilton of the University of Maryland, College Park, and Michael Skrutskie, of the University of Virginia, Charlottesville. They used the longer-wavelength infrared camera on Spitzer, called the multiband imaging photometer, and did their observations before Spitzer ran out of coolant in May and began its "warm" mission.
The dark and light side of Iapetus. Credit: NASA/JPL/Space Science Institute
"For more than 300 years, people have been trying to explain the appearance of Saturn's moon Iapetus, (which was discovered by Giovanni Cassini in 1671) and why one side of the moon is light and the other very dark," said Verbiscer. "For the past 35 years, another moon, Phoebe has come up as a possible explanation, , as there is a connection between those two moons. Phoebe itself is very, very dark, and it matches the albedo or brightness of the dark material of Iapetus' leading hemisphere. Phoebe has a retrograde orbit and Iapetus is in a pro-grade orbit. So if particles are launched off of Phoebe and spiral inward toward Saturn they would be smacking Iapetus right on that leading hemisphere."

Verbiscer said that dynamically, this explanation for Iapetus' dark side has been talked about and tried to be modeled. But no one had thought of using Spitzer to look for any dust in that area. "So, that was our idea," she said. "The title of our proposal was 'A New Saturnian Ring.' We were definitely looking for a dust structure associated with Phoebe and in the same orbit, and that is precisely what we see."

Verbiscer said it would be very difficult even for the Cassini spacecraft, and especially the imaging cameras to see this ring, since it shows up only in infrared. Plus Cassini is inside of this ring, and would have to look out past Saturn's other rings. "This ring is so big but yet so faint, it would be difficult to know when you were looking at it and when you weren't."

The vertical height and orbital inclination of this ring matches perfectly with Phoebe's orbit on the sky. "If you were to plot where Phoebe appears over time as it goes around Saturn, the ring matches exactly, Verbiscer said. "Think of a quarter spinning on a table; the ring has the same vertical tip to it, and Phoebe's orbit does the same type of thing."

As to whether the dust particles from Phoebe itself or if Phoebe "shepherding" some particles into that configuration, the scientists don't have definite proof, but most likely the dust particles are from Phoebe. "We don't have firm confirmation of that, but it is strongly suggestive that it comes from Phoebe," Verbiscer said. "The materials all together amounts to what you would get from excavating a crater about a kilometer in diameter on Phoebe."

Phoebe is 200 km across and heavily cratered, so a 1 km crater is not an overly huge crater. "So, we can't look at a certain crater on Phoebe and say that one created the ring," Verbiscer explained. "It's likely it's from several different smaller impacts, and ring keeps getting supplied from subsequent impacts and micrometeorites hitting Phoebe, launching material into this ring, putting dust and material from Phoebe's surface into a Phoebe-like orbit."

But there still is a bit of a mystery about the color of Iapetus' leading hemisphere.

The two moons have frequently been compared in composition, and in near infrared, they share absorption features. In the ultraviolet, however, the spectra don't match as well. "In terms of color, on Iapetus, the dark color looks a little more red compared to Phoebe, so there is a little color mismatch," Verbiscer said. "It could be the particles launched from Phoebe mix with whatever is on Iapetus, which might account for the color difference. That might be something interesting to explore, to do some spectral mixing models to come up with some primordial Iapetus material and mix with Phoebe's material see if they get reddened somehow."

The ring itself is too faint to take a spectra to try and determine what materials make up the ring, but the assumptions are the materials come from the top surface of Pheobe's cratered surface, which also might include some ice. Cassini close-ups of the moon from 2004 show bright craters, hinting that ice is close to the surface.

Spitzer was able to sense the glow of the cool dust, which is only about 80 Kelvin (minus 316 degrees Fahrenheit). Cool objects shine with infrared, or thermal radiation; for example, even a cup of ice cream is blazing with infrared light. "By focusing on the glow of the ring's cool dust, Spitzer made it easy to find," said Verbiscer. >>

[bystander]

NASA Space Telescope Discovers Largest Ring Around Saturn
NASA - JPL - Spitzer Space Telescope
Press Release SSC2009-19 - 2009 October 06

[neufer]

<<In Greek mythology "golden-wreathed" Phoebe (Greek: Φοίβη Phoibe), the feminine counterpart of the name Phoebus, was one of the original Titans, who were one set of sons and daughters of Uranus and Gaia. Her consort was her brother Coeus, with whom she had two daughters, Leto, who bore Artemis and Apollo, and Asteria, a star-goddess who bore an only daughter Hecate.>>

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http://antwrp.gsfc.nasa.gov/apod/ap060212.html
http://antwrp.gsfc.nasa.gov/apod/ap040710.html
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<<Most of Saturn's inner moons have very bright surfaces, but Phoebe's albedo is very low (0.06), as dark as lampblack. The Phoebean surface is extremely heavily scarred, with craters up to 80 kilometres across, one of which has walls 16 kilometres high. Phoebe's dark coloring initially led to scientists surmising that it was a captured asteroid, as it resembled the common class of dark carbonaceous asteroids. These are chemically very primitive and are thought to be composed of original solids that condensed out of the solar nebula with little modification since then.

However, images from the Cassini-Huygens space probe indicate that Phoebe's craters show a considerable variation in brightness, which indicate the presence of large quantities of ice below a relatively thin blanket of dark surface deposits some 300 to 500 metres (980 to 1,600 feet) thick. In addition, quantities of carbon dioxide have been detected on the surface, a finding which has never been replicated on an asteroid. It is estimated that Phoebe is about 50% rock, as opposed to the 35% or so that typifies Saturn's inner moons.

For these reasons, scientists are coming to believe that Phoebe is in fact a captured Centaur, one of a number of icy planetoids from the Kuiper belt that orbit the Sun between Jupiter and Neptune. Phoebe is the first such object to be imaged as anything other than a dot.

<<The centaurs are an unstable orbital class of minor planets named after the mythological race of centaurs because they behave as half asteroid and half comet. Centaurs have transient orbits that cross or have crossed the orbits of one or more of the giant planets, and have dynamical lifetimes of a few million years. The first centaur-like object to be discovered was 944 Hidalgo in 1920. However, they were not recognized as a distinct population until the discovery of 2060 Chiron in 1977. The largest known centaur is 10199 Chariklo, discovered in 1997, which at 260 km in diameter is as big as a mid-sized main-belt asteroid.

No centaur has been photographed up close, although there is evidence that Saturn's moon Phoebe, imaged by the Cassini probe in 2004, may be a captured centaur. In addition, the Hubble Space Telescope has gleaned some information about the surface features of 8405 Asbolus. As of 2008, three centaurs have been found to display cometary comas: Chiron, 60558 Echeclus, and 166P/NEAT. Chiron and Echeclus are therefore classified as both asteroids and comets. Other centaurs such as 52872 Okyrhoe are suspected of showing cometary activity. Any centaur that is perturbed close enough to the Sun is expected to become a comet.>>

Material displaced from Phoebe's surface by microscopic meteor impacts may be responsible for the dark surfaces of Hyperion. Debris from the biggest impacts may have been the building blocks of the other moons of Phoebe's group—all of which are less than 10 km in diameter.

The Phoebe ring is one of the rings of Saturn. This ring is tilted 27 degrees from Saturn's equatorial plane (and the other rings). It extends from 128 to 207 times the radius of Saturn; Phoebe orbits the planet at an average distance of 215 Saturn radii. The ring is about 20 times as thick as the diameter of the planet. Since the ring's particles are presumed to have originated from micrometeoroid impacts on Phoebe, they should share its retrograde revolution, which is opposite to the orbital motion of the next inner moon, Iapetus. Inwardly migrating ring material would thus strike the latter's leading hemisphere, possibly causing the two-tone coloration of that moon. Although very large, the ring is virtually invisible—it was discovered using NASA's infra-red Spitzer Space Telescope. The existence of the ring was proposed in the 1970s by Joseph Burns of Cornell University. The discovery was made by Anne J. Verbiscer and Michael F. Skrutskie (of the University of Virginia) and Douglas P. Hamilton (of the University of Maryland, College Park) and published in Nature.>>

[geckzilla]

Yay! I have been wondering what Iapetus has been running into ever since that APOD from two years ago first presented the question to me. This sounds like a really plausible explanation.

[pacfandave]

A picture of Saturn's newly discovered ring has been in the newspapers and on-line, everywhere but where one would think it would show up first--APOD. Instead, we get often years-old photos of novae, dust lines, and galaxy clusters. Yawn. Let's start a pool. The one who picks the decade when photos of the impact on the moon of the $79 mil ice-seeking probe first show up on APOD wins.

[geckzilla]

I'm gonna put my wager up for never, since no images of the impact seem to exist.

I'm sure APOD will get some Saturn ring up once the information on them is more solidified. APOD isn't about getting that breaking news astronomy to your face as quick as possible. Things take time.

[apodman]

File this one under planetary phenomena. APODs bubble up like bones from the tar pits. They need to be cleaned with solvent and wired together before they can be put on display.

[The Code]

Just for the conversation only,,, do not bite me...!

6/10/2009 New rings Found,, On your Door step.. lol

Lots more to understand I guess...

Mark

[geckzilla]

Looks like Saturn's new ring gets to be tomorrow's APOD.

[bystander]

Looks like Saturn's new ring gets to be tomorrow's APOD.

Wonder what picture they will use. Besides the two already shown here, there is a third one in the Spitzer PR visuals.

[neufer]

Is Phoebe the proverbial "Centaur chasing its own dust tail?"

[bystander]

Is Phoebe the proverbial "Centaur chasing its own dust tail?"

Shouldn't she be chasing in the opposite direction? Besides which, that looks more like a dog than a centaur.

[kovil]

"It is very, very faint; extremely tenuous," Verbiscer told Universe Today. "If you were standing inside the ring you wouldn't even know it. In a cubic kilometer of space there are only 10-20 particles. The particles are about the same size as fog particles, but they are very spread out. We're just looking at the thermal emissions these little particles are giving off; we're not looking at reflected sunlight at all in the observations we did with Spitzer. That's what makes Spitzer the perfect instrument to use to try and find such a dust structure. This ring is completely analogous to debris disks around other stars that Spitzer has observed."

"Fog particles" or finely divided dust. What makes 'finely divided dust' ? Sputtering !

"Sputtering is a process whereby atoms are ejected from a solid target material due to bombardment of the target by energetic ions. It is commonly used for thin-film deposition, etching and analytical techniques.
Physical sputtering is driven by momentum exchange between the ions and atoms in the material, due to collisions. The incident ions set off collision cascades in the target. When such cascades recoil and reach the target surface with an energy above the surface binding energy, an atom can be ejected. If the target is thin on an atomic scale the collision cascade can reach the back side of the target and atoms can escape the surface binding energy `in transmission'. The average number of atoms ejected from the target per incident ion is called the sputter yield and depends on the ion incident angle, the energy of the ion, the masses of the ion and target atoms, and the surface binding energy of atoms in the target."

"The primary particles for the sputtering process can be supplied in a number of ways, for example by a plasma, an ion source, an accelerator or by a radioactive material emitting alpha particles.
A different mechanism of physical sputtering is heat spike sputtering. This may occur when the solid is dense enough, and the incoming ion heavy enough, that the collisions occur very close to each other. Then the binary collision approximation is no longer valid, but rather the collisional process should be understood as a many-body process. The dense collisions induce a heat spike (= thermal spike), which essentially melts the crystal locally. If the molten zone is close enough to a surface, large amounts of atoms may sputter due to flow of liquid to the surface and/or microexplosions[6]. Heat spike sputtering is most important for heavy ions (say Xe or Au or cluster ions) with energies in the keV–MeV range bombarding dense but soft metals with a low melting point (Ag, Au, Pb, ...). The heat spike sputtering often increases nonlinearly with energy, and can for small cluster ions lead to dramatic sputtering yields per cluster of the order of 10000."

"The term electronic sputtering can mean either sputtering induced by energetic electrons (for example in a transmission electron microscope), or sputtering due to very high-energy or highly charged heavy ions which lose energy to the solid mostly by electronic stopping power, where the electronic excitations cause sputtering. Electronic sputtering produces high sputtering yields from insulators, as the electronic excitations that cause sputtering are not immediately quenched, as they would be in a conductor. One example of this is Jupiter's ice-covered moon Europa, where a MeV sulfur ion from Jupiter's magnetosphere can eject up to 10,000 H2O molecules."

[neufer]

"It is very, very faint; extremely tenuous," Verbiscer told Universe Today. "If you were standing inside the ring you wouldn't even know it. In a cubic kilometer of space there are only 10-20 particles. The particles are about the same size as fog particles, but they are very spread out. We're just looking at the thermal emissions these little particles are giving off; we're not looking at reflected sunlight at all in the observations we did with Spitzer. That's what makes Spitzer the perfect instrument to use to try and find such a dust structure. This ring is completely analogous to debris disks around other stars that Spitzer has observed."

"Fog particles" or finely divided dust. What makes 'finely divided dust' ? Sputtering !

The same thing that makes cometary dust tails?

<<Solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them. The streams of dust and gas thus released form a huge, extremely tenuous atmosphere around the comet called the coma.>>

But what causes Phoebe's coma dust to orbitally decay so it can be swept up by Iapetus
...the Poynting–Robertson effect/drag?

<<The Poynting–Robertson effect/drag, is a process by which solar radiation causes a dust grain in the solar system to slowly spiral inward. The drag is essentially a component of radiation pressure tangential to the grain's motion. From the perspective of the grain of dust circling the Sun, the Sun's radiation appears to be coming from a slightly forward direction (aberration of light). Therefore the absorption of this radiation leads to a force with a component against the direction of movement. In the frame of the solar system (b), the re-emission is beamed anisotropically, and hence the photons carry away angular momentum from the dust grain. The Poynting–Robertson drag can be understood as an effective force opposite the direction of the dust grain's orbital motion, leading to a drop in the grain's angular momentum. It should be mentioned that while the dust grain thus spirals slowly into the Sun, its orbital speed increases continuously.

Rocky [zodiacal light] dust particles sized a few micrometers need a few thousand years
to get from 1 AU distance to distances where they evaporate.>>

The Poynting–Robertson effect/drag on Phoebe's rocky dust particles sized a few micrometers probably needs a few hundred thousand years to orbitally decay to where Iapetus sweeps them up (since the solar photon density is ~ hundred times weaker at ~ 10 AU).

[kovil]

<<Solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them. The streams of dust and gas thus released form a huge, extremely tenuous atmosphere around the comet called the coma.>> from Wikipedia

Not to get into an argument with the Wiki contributor or Chris Peterson, but; (quotes from various sources follow; and this is why I said that "Comets are NOT dirty snowballs, they are exactly the same as asteroids". They just have a different orbit than asteroids. If you take an asteroid and give it a cometary orbital path, you'll have and see a comet !)

Then, in January 2004, the Stardust spacecraft passed by Comet Wild 2, identifying a dozen jets of material exploding from the nucleus. The craft plowed through surprisingly dense pockets of dust swirling around the comet, but investigators were astonished that they could not find even a trace of water on the surface, despite the energetic activity.

By the time of “Deep Impact” on July 4, 2005, comet theory had fragmented into mutually contradictory hypotheses—a comet was a dirty snowball, an icy dirtball, a gravel pile, a rubble heap, or an easily-fragmented fluffball.

NASA’s recent report on the Deep Impact mission suggests that investigators found a smattering of water ice on the surface of comet Tempel 1. The problem is that, to account for the water supposedly being “exhaled” by Tempel 1, the investigators needed 200 times more exposed water-ice than they could find.

The absence of detectable water on the nucleus of Wild 2 was particularly mystifying because the pictures revealed cavernous craters with steep cliffs exposing deep subsurface material. The absence of water in such circumstance is no small problem!

The case of missing water is even more severe in the instance of Deep Impact and Comet Tempel 1. If a thin crust of dust hides the water below the surface of the nucleus, one would think that a newly formed crater, estimated to be the size of a football field and perhaps 65 feet deep, would be exactly what was needed to add life to the comet’s water-producing ability. The ice certainly could not be more than a few feet beneath the insulating material—and that’s thinking generously. Any deeper than that, and the Sun’s heating could have nothing to do with the comet’s discharge.

The explosion removed many thousands of tons of material. But prior to impact, the calculated “water” output was 550 pounds per second; and not long after the impact, the calculated output was, once again, 550 pounds per second. So despite the impressive explosion, the envisioned sub-surface water refused to reveal itself. By NASA’s own calculations, therefore, Deep Impact has only made matters worse for standard theory.

Fine cometary dust. Cathode sputtering has an effect that is simply “beyond the reach” of evaporating volatiles. It can create an exceedingly fine dust down to 1 micrometer or even finer. (One micrometer is just 40 millionths of an inch). This unique capability of cathode sputtering is why the process is used in the manufacture of highly reflective mirrors for modern telescopes.

Astronomers could not understand what occurred when the 800-pound Deep Impact projectile hit the Comet Temple 1 nucleus. An enormous volume of an extraordinarily fine dust was thrown into space at high speed, creating an extremely bright cloud due to the dust’s remarkable reflectivity. NASA scientists estimated that the dust particles were only .5 to 1 micrometer in diameter.

No one should be permitted to state as fact the idea that large volumes of “water” fill the comas of comets. The scientific instruments do not see water. What they see as the most abundant companion of cometary dust is the “hydroxyl” radical, OH.

In considering the source of OH, the theorists possess a deficient toolkit. Standard theory has little to work with other than photolysis, the process by which light absorption can break a molecule down into its separate building blocks. But conventional theorists, already “knowing” that the coma is a product of water boiling off the nucleus, concluded with equal confidence that the coma’s water has been broken down by the Sun’s ultraviolet radiation, forming the hydroxyl radical (OH) along with atomic hydrogen and oxygen. By this reasoning, the abundance of OH in a comet's coma becomes a direct pointer to the abundance of water held by the nucleus.

In fact there are many avenues for generating OH if you allow for electric discharge and “sputtering” by protons to remove silicates, carbonates, and other rock minerals, together with organic molecules, from the comet’s surface. Electrical sputtering technology is well established in industrial applications, but is far from the minds of astronomers as they consider the mysteries of the comet, despite the fact that sputtering is the industrial process that creates the telescope mirrors they use during their research !

Comets spend 99% of their time far from the sun where the sun's electric field has a low positive charge density. Because comets move slowly at their aphelion, their electric charge reaches equilibrium with the weak radial solar electric field at that distance, in to what would be described as a highly negative charge in relation to the sun's highly positive charge. As they get closer to the sun, however, their nuclei speed into regions of an increasingly positive charge density and varying electrical flux. Their relative negative polarity and charge characteristics respond to the increasingly positive solar e-field forces, so a coma (charge sheath, or electric Double Layer) forms around them. Discharge jets flare up and move across the surface very much like the plumes of Jupiter's moon, Io. Sparks and arcs as the electrical charge imbalances seek equilibrium are what enable the sputtering, and create the 'finely divided dust' that forms the comet's coma. If the charge imbalance becomes too great, the nuclei may explode like an over-charged capacitor, breaking into fragments.

[geckzilla]

Hey kovil, you said "quotes from various sources follow" but I can't tell what you wrote and what was quoted. Could you highlight the parts that are quoted and press the Quote button up there to wrap them in quote tags? Or maybe I'm confused, because it looks like you wrote all of that.

[bystander]

Hey kovil, you said "quotes from various sources follow" but I can't tell what you wrote and what was quoted. Could you highlight the parts that are quoted and press the Quote button up there to wrap them in quote tags? Or maybe I'm confused, because it looks like you wrote all of that.

It would also be nice if you provided the source of each quote.

[apodman]

For spectators who are new to this sport, here it is what is going on: Kovil is trying to sneak plasma cosmology and electric universe into the discussion as usual. But he is trying to be subtle about it because flagrant promotion of such pseudo-science is met with scorn. Others are trying to get kovil to be more specific so they can find a point to discuss. But with the pc and eu sales staff, all discussion leads to the same point. That point is simply a load of non-scientific crap invented for profit by authors. It's not worth researching here, but most quotes posted by pc and eu promoters turn out to be from pc and eu web sites, not from legitimate scientific sources. Much unquoted material posted by pc and eu promoters also turns out to be copied and pasted without credit from pc and eu web sites. Google a silly phrase and see that this is true.

[geckzilla]

I see what you did there. Google did the trick. I already get instantly skeptical anytime someone makes a post with an overabundance of quotation marks. It's funny how you can manipulate people into thinking something by using them. Wording too vague? Don't know how to explain something? Need to say something without actually saying it? Use quotation marks around key words to induce your readers' imaginations to fill in the blanks with whatever you're alluding to so you don't have to properly explain yourself.

[canuck100]

For the curious, here is a debunking of many of James McCanney's wild claims including

debunk 'comets are not dirty snowballs'
http://www.badastronomy.com/bad/misc/mc ... balls.html
debunk solar wind is electrically charged
http://www.badastronomy.com/bad/misc/mc ... rwind.html
debunk 'comets don't lose mass, they gain it'
http://www.badastronomy.com/bad/misc/mc ... sloss.html
debunk: 'comets are huge - hale bopp was as big as the moon' LOL
http://www.badastronomy.com/bad/misc/mc ... _huge.html

[bystander]

Click to play embedded YouTube video.

Amy Okuda ("The Guild") flies to Saturn to observe a new giant ring around the planet: the largest ring ever discovered in our Solar System, but one that was only recently revealed through infrared observations by NASA's Spitzer Space Telescope in 2009.

While there, she and Irwin -- voiced by Wil Wheaton ("Star Trek: the Next Generation," "Big Bang Theory") -- encounter an old enemy, and must defeat their sinister plot. Ed Wasser also stars.

To view more comedic (but educational!) NASA videos featuring Sean Astin, Felicia Day, Mark Hamill, Linda Hamilton, Dean Stockwell, George Takei, Ed Wasser, Betty White and more, visit:

http://coolcosmos.ipac.caltech.edu/videos/irrelevant