A Colorful Life In The Outer Planets
Atmospheric features on Uranus and Neptune are revealed in images taken with the Space Telescope Imaging Spectrograph and the Advanced Camera for Surveys aboard NASA's Hubble Space Telescope. A wider view of Uranus reveals the planet's faint rings and several of its satellites. The observations were taken in August 2003.
Uranus and Neptune:
At first glance, the top row of images makes the planets appear like twins. But the bottom row reveals that Uranus and Neptune are two different worlds. Uranus's rotational axis, for example, is tilted almost 90 degrees to Neptune's axis. The south poles of Uranus and Neptune are at the left and bottom, respectively. Both are tilted slightly toward Earth. Uranus also displays more contrast between both hemispheres. This may be caused by its extreme seasons.
Both planets display a banding structure of clouds and hazes aligned parallel to the equator. Additionally, a few discrete cloud features appear bright orange or red. The color is due to methane absorption in the red part of the spectrum. Methane is third in abundance in the atmospheres of Uranus and Neptune after hydrogen and helium, which are both transparent. Colors in the bands correspond to variations in the altitude and thickness of hazes and clouds. The colors allow scientists to measure the altitudes of clouds from far away.
Uranus (A Wider View):
The bright satellite on the lower right corner is Ariel, which has a snowy white surface. Five small satellites with dark surfaces can be seen just outside the rings. Clockwise from the top, they are: Desdemona, Belinda, Portia, Cressida, and Puck. Even fainter satellites were imaged in deeper exposures, also taken with the Advanced Camera in August 2003.
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First Detection Of CO In Uranus
Paris - Dec 18, 2003
A team from Paris Observatory, led by Thérèse Encrenaz (LESIA), has just detected for the first time the molecule of carbon monoxide (CO) in the atmosphere of Uranus. The origin of this molecule is probably external to the planet, for example due to micrometeorites.