Discovering U1:A new moon for Uranus

The image was so faint that scientists at the Jet Propulsion Laboratory in Pasadena, Calif., checked to make sure it was not the result of a blemish on the camera lens or static distorting the telemetry. But it was real, a tiny circle that represented a previously undiscovered moon only 35 miles in diameter, orbiting 37,500 miles above the murky atmosphere of the planet Uranus.

The photograph, transmitted across 1.8 billion miles of emptiness, was taken by the indefatigable traveler Voyager 2 as it approached its Jan. 24 rendezvous with the solar system’s seventh planet. On that day, the spacecraft will swoop to within 50,000 miles of Uranus, which last week still looked to Voyager’s cameras like a featureless, cloud-covered, blue-green disk. The temporary designation of the new moon, 1985 Ul, seems rather prosaic when compared with Uranus’ five other satellites: Miranda, Ariel, Umbriel, Titania and Oberon. But that should change this summer when the International Astronomical Union meets to assign permanent names to new discoveries. The I.A.U. might have its work cut out for it. Astronomers think Voyager may soon spot as many as 18 more Uranian moons.