Japanese observatory views Uranus and two moons
Posted: March 17, 2002

Credit: National Astronomical Observatory of Japan
This image of Uranus, its ring system, and two of its satellites Miranda (top-center) and Ariel (bottom-left) is from Subaru Telescope's Coronagraphic Imager with Adaptive Optics (CIAO) combined with Subaru Telescope's adaptive optics system (AO).

On March 13, 1781, British astronomer William Herschel discovered an object that appeared large compared to a star during observations with a homemade 6.3 inch (16 cm) telescope. The object, which was initially thought to be a comet, turned out to be a new planet outside Saturn's orbit, and was named Uranus.

Uranus revolves around the Sun in approximately 84 years on an elliptic orbit whose average radius is approximately 1.7 billion miles (2.8 billion kilometers). Unlike other planets, Uranus spins on its side with respect to its orbital plane. Since 1851, over 10 satellites and 10 rings have been discovered around Uranus.

This image was taken during tests of the combined use of CIAO and AO in July 2001. It combines near-infrared images in three different filters, so the colors are not the same as what we would see in the optical. In this color scheme, methane, the dominant component of Uranus's atmosphere, shows up as blue.

Scientists from several research institutes and universities, in addition to the National Astronomical Observatory of Japan, participated in the development of CIAO and Subaru Telescope's AO system. The team from Kobe University processed this image.