Posted on 04/10/2006 11:14:40 AM PDT by presidio9
Astronomers knew there was something odd going on when they looked for Uranus' newly discovered outer rings. For starters, they could only find one. After months of analysis, they figured out why: Unlike its red partner, the missing ring is so blue, it fell outside the telescope's range.
"It's funny that this research got started by something we didn't see," said Imke de Pater, with the University of California at Berkeley and lead author of a paper describing the discovery in this week's journal Science.
The initial discovery of a pair of outer rings circling Uranus was made by astronomers using the Hubble Space Telescope last year. De Pater and her team wanted to follow up the finding using the ground-based Keck telescope, which is sensitive in the near-infrared.
"We went out in October to image both rings and we simply couldn't see the outer one. We should have easily seen it if it was a normal ring. The interesting part was that the outer ring was the one that was the brighter one in the Hubble images," de Pater said in an interview with Discovery News.
The scientists ran computer models simulating the rings' brightness until they came upon the answer: the outer ring is distinctly blue, a very unusual color for planetary rings. Only Saturn's E-ring is similarly colored and the researchers suspect Uranus' ring is even bluer than that.
De Pater theorizes that the materials in Uranus' blue ring are smaller than a micron, so tiny that the photons of light streaming from the sun move the particles around.
"When dust is smaller than or comparable to the wavelength of light, the reflected color is dominated by particle size effects rather than the intrinsic color of the material, " de Pater wrote in the Science article.
When the tiniest-sized grains dominate, blue light is reflected, she said. If larger-sized grains are more common, the color is red.
Like Saturn's E-ring, the outermost ring of Uranus peaks near the orbit of one moon. Enceladus, which orbits Saturn, is believed to contribute the particles that comprise the ring. Scientists suspect Uranus' tiny moon Mab may play a similar role for its blue ring.
Unlike Enceladus, which has plumes of gas and dust jetting from its surface into space, any contributions from Mab, which is 20 times smaller than Enceladus and unlikely to be as geologically active, probably have a less exotic explanation: Dust particles created by micrometeorite impacts were blasted into space.
The discovery sets the stage for an intensive probe of Uranus next year when the rings will appear edge-on to Earth, making even the faintest rings 100 times brighter, and enabling scientists to make measurements of the rings' heights.
Especially in January and February.
This ought to be fun.......
You can never have too many Uranus jokes.
I'm not going to say it...
Blame the Tidy Bowl man?
Yeah, I know it's caused by particle size, not temperature, but I'll take any excuse to quote Tom Waits.
Take the tidy-bowl cleaner out and raise the seat.
Problem solved.
Does "20 times smaller" mean "1/20 the size"?
I thought a blue ring around uranus meant you wore cheap jeans that got wet.
too smart a subject for me but I can dance the Macaranus.
Red, white and blue. Looks patriotic! :)
I've heard it pronounced, "Uriness," but that doesn't help, either :)
Only funny thing was ever said on Futurama:
Professor: "They got rid of that name over 100 years ago to get rid of that stupid joke"
Fry: "What's it called now?"
Professor: "Urectum"
LOL, that is funny.
I wonder what could cause a bruise like that?
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