Astronomers have created the most detailed, high-resolution images of Uranus ever taken, showing off its complex weather patterns and several features that scientists don’t completely understand.
Uranus is the seventh planet from the sun and an ice giant, composed mainly of frozen methane, water, ammonia, and hydrocarbons. For most people, the iconic image of Uranus was taken in 1986 by the Voyager 2 spacecraft, the only man-made probe to visit the planet, showing a smooth blue-green world. But this featureless marble doesn’t represent Uranus’ true face, which is swept with intricate cloudy bands, much like Jupiter and Saturn.
Because Uranus is so far away, most telescopes can’t resolve much more than the bland facade that Voyager saw. By combining together many infrared camera images from the world-class Keck telescopes in Hawaii, scientists were able to reduce noise and pick out the details of Uranus’ atmosphere. The results were presented at the American Astronomical Society’s Division of Planetary Sciences meeting in Reno, Nevada on Oct. 17.
These images revealed circulating clouds, enormous hurricanes, and, just south of the planet’s equator, a never-before-seen scalloped wave pattern. The braid-like feature could be caused by wind shear or atmospheric instability but no one knows for sure. The data also showed that clouds deep mainly composed of hydrogen, helium, and methane in Uranus’ atmosphere race by at 560 miles per hour.
Seeing Uranus’ bands highlights an important quirk of the planet: It is tilted almost completely over on its side. Rather than having cloud run left to right across its face, as on Jupiter or Saturn, the bands travel up and down. Its “North Pole” is located at the right of the images above and features unusual convective spots that may indicate the presence of an enormous polar hurricane.
Like on the other giant planets in our solar system, weather systems are fairly stable on Uranus, often remaining at the same latitude for years at a time. These planet-wide storms are actually much less intense than similar weather on Earth since they sun is what ultimately drives all weather and it is 900 times weaker out at Uranus than on our planet. But sometimes Uranian storms undergo bizarre changes in size and shape that seem to be more powerful than would be possible given the little amount of solar energy arriving in the outer solar system.
Image: Courtesy of Lawrence Sromovsky, Pat Fry, Heidi Hammel, Imke de Pater
