Los Angeles ? Astronomers aided by the Hubble Space Telescope have spied two more rings encircling Uranus, the first additions to the planet’s ring system in nearly two decades.

The faint, dusty rings orbit outside of Uranus’ previously known rings, but within the orbits of its large moons, said Mark Showalter, an astronomer at the SETI Institute in Mountain View, Calif., who made the discovery.

Details will appear online today in the journal Science. The discovery, announced Thursday, means scientists now believe the seventh planet from the sun possesses 13 rings.

Scientists peering through the Hubble Space Telescope made the latest ring discoveries in 2004. Then they went back to process hundreds of images taken by Voyager and found the rings in the pictures.