New images taken by the Keck Observatory have revealed that the original bland photos taken by Voyager are way off the mark of the planets actual appearance.
The Voyager probe made its flyby of Uranus in 1986 and took photos that seemed to show a featureless, uniform blue-green orb.
New observations by the Keck Observatory are showing that Uranus actually has an active weather system in distinct bands, much like that of Saturn or Jupiter. In the above image, the white features are high altitude clouds like Earth’s cumulous clouds, while the bright blue-green features are thinner high-altitude clouds akin to cirrus clouds. Reddish tints indicate deeper cloud layers. Just south of the equator is a never-before-seen scalloped wave pattern similar to instabilities that develop in regions of horizontal wind shear due to excessive differences in velocity.
The astronomers found that in the planet’s deep atmosphere, comprised of hydrogen, helium and methane, winds blow mainly in east-west directions at speeds up to 560 miles per hour, in spite of the small amounts of energy available to drive them. Its atmosphere is the coldest in our solar system, with cloud-top temperatures in the minus 360-degree Fahrenheit range, partly due to Uranus’ great distance from the sun.
“The sun is 900 times weaker than on Earth, so you don’t have the same intensity of solar energy driving the system as we do here,” said Sromovsky. “Thus, the atmosphere of Uranus must operate as a very efficient machine with very little dissipation. Yet it undergoes dramatic variations that seem to defy that requirement.”
Large weather systems, which are probably much less violent than the storms we know on Earth, behave in bizarre ways on Uranus. Some stay at fixed latitudes and undergo large variations in activity, while others have been seen to drift towards the equator, while undergoing great changes in size and shape.
The study was led by Larry Sromovsky, a planetary scientist at the University of Wisconsin, Madison. In addition to de Pater, other team members are Pat Fry of the University of Wisconsin and Heidi Hammel of the Association of Universities for Research in Astronomy. The team will report the details of their observations Oct. 17 at a meeting of the American Astronomical Society’s Division of Planetary Sciences in Reno, Nevada.
This article summarised from a release by the University of Wisconsin, Madison, and an article by the University of California, Berkeley.
The abstract of the study, “First Views of North Polar Clouds and Circulation on Uranus” – Lawrence A. Sromovsky, P. M. Fry, H. B. Hammel, I. de Pater and K. A. Rages, is available here.