October 21, 2012
New Images: Scientists Puzzled By Uranus Weather Patterns
April Flowers for redOrbit.com — Your Universe Online
New, exquisitely detailed, high-resolution images of Uranus show off its complex weather patterns and new features of the planet that scientists can't explain yet.Uranus, the seventh planet from the Sun, is an ice giant composed mainly of frozen methane, water, ammonia and hydrocarbons. In 1986, Voyager 2 passed by Uranus and returned the iconic image that most associate with the planet. This image showed a smooth, blue-green featureless world. This newest image reveals something different, a world swept with intricate cloudy bands, much like Jupiter and Saturn.
Uranus is at such a distance from Earth that most telescopes can't resolve much more than the bland faÃ§ade that Voyager saw. The new image combines many different infrared camera images from the Keck Telescopes in Hawaii. Using this method, scientists were able to reduce background noise and pick out the details of Uranus' atmosphere. The team presented their results at the American Astronomical Society´s Division of Planetary Sciences meeting.
"We're seeing some new things that before were buried in the noise [in the data]," Larry Sromovsky, a University of Wisconsin-Madison planetary scientist, said.
Circulating clouds, enormous hurricanes, and a never-before-seen scalloped wave pattern just south of the planet's equator, were revealed by the new composite images. The braid-like scalloped pattern could be caused by wind shear or atmospheric instability, but the cause is unknown so far. The data also showed that hydrogen, helium and methane clouds race by in the atmosphere at 560 miles an hour.
The image revealed the bands around Uranus, highlighting an important quirk of the planet. Uranus is tilted almost completely on its side, with the cloud bands running up and down instead of side to side like those on Jupiter do. Uranus' North Pole features unusual convective spots that may indicate the presence of an enormous polar hurricane.
It appears weather systems are fairly stable on Uranus, like the other giant planets in our solar system. The weather systems often remain at the same latitude for years at a time, with planet-wide storms that are much less intense than similar weather on Earth. The Sun drives weather and it is 900 times weaker in its effect on Uranus than on Earth. Sometimes, however, Uranian storms have bizarre changes in shape and size that seem to be more powerful than would be possible given the little amount of solar energy that arrives in the outer solar system.