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Hubble Uncovers Smallest Moons Yet Seen Around Uranus

These images, taken with the NASA Hubble Space Telescope's Advanced Camera for Surveys (ACS), show several faint moons circling Uranus, including a newly detected moon and a rediscovered satellite. The planet's ring system can also be seen.

NASA, M. Showalter (Stanford University/NASA Ames Research Center), J. Lissauer (NASA Ames Research Center)

Astronomers have discovered two of the smallest moons yet found around Uranus. The new moons, uncovered by NASA's Hubble Space Telescope, are about 8 to 10 miles across (12 to 16 km) - about the size of San Francisco. They are so faint that they eluded detection by the Voyager 2 spacecraft, which discovered 10 small satellites when it flew by the gas giant planet in 1986.

The newly detected moons are orbiting even closer to the planet than the five major Uranian satellites, which are several hundred miles wide. The two new satellites are the first inner moons of Uranus discovered from an Earth-based telescope in more than 50 years. Images taken on Aug. 25, 2003 with Hubble's Advanced Camera for Surveys were used to make the discovery. The International Astronomical Union (IAU) will announce the finding today. The Hubble telescope observations also helped astronomers confirm the discovery of another tiny moon that had originally been spotted in Voyager pictures.

For more information about the image, please read the full story on the Hubble site at htmlhttps://hubblesite.org/contents/news-releases/2003/news-2003-29.html.