You Can Never Be Too Thin or Too Gaseous

Near infrared images of Uranus before and after the AO system on Keck was turned on. The images on the left show Uranus at K (2.2 micron) and H (1.6 micron) bands as we saw the planet before Keck was equipped with Adaptive Optics. On the right you see the improvement in image quality (sharpening) after the AO system was turned on. (Image credit: Heidi B. Hammel and Imke de Pater)
Near infrared images of Uranus before and after the AO system on Keck was used (Image credit: Heidi B. Hammel and Imke de Pater)

What’s the latest at Uranus? According to Professor Imke de Pater (University of California, Berkeley) and Heidi Hammel (Space Science Institute), the 7th planet out from the Sun is not the boring and unchanging planet everybody thinks it is. The weather’s changing as the southern hemisphere summer at Uranus comes to a close. There are more clouds in the upper atmosphere than scientists saw when Voyager first approached the planet back in 1986. This is due to high-altitude cloud activity perpetrated by strong convection currents in the atmosphere. If you look at the planet with infrared-enabled instruments, those clouds really stand out. And, as an added bonus, there’s a newly discovered dim ring to be checked out. This new one, called 1986U2R, is—like the other rings in the system—only only a single layer of boulder-sized particles thick. That’s downright diaphanous by ring standards!

These discoveries weren’t made with a flyby spacecraft. Instead, the Uranus observation teams have been using the Keck telescope out on Mauna Kea (Hawaii), and the careful application of adaptive optics (a method to “erase” the effects of atmospheric aberration from ground-based observations).

What’s next for Uranus as the seasons change? Maybe more clouds will bubble their way up from the depths of the planet’s atmosphere. Nobody’s quite sure, since this is the first time the planet’s seasons have changed since high-resolution telescopes like the Keck and others have been in use.

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