Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
November 23, 1997
Explanation: On October 10th, 1846, William Lassell was observing the newly discovered planet Neptune. He was attempting to confirm his observation, made just the previous week, that Neptune had a ring. But this time he discovered that Neptune had a satellite as well. Lassell soon proved that the ring was a product of his new telescope's distortion, but the satellite Triton remained. The above picture of Triton was taken in 1989 by the only spacecraft ever to pass Triton: Voyager 2. Voyager 2 found fascinating terrain, a thin atmosphere, and even evidence for ice volcanoes on this world of peculiar orbit and spin. Ironically, Voyager 2 also confirmed the existence of complete thin rings around Neptune - but these would have been quite invisible to Lassell!
Authors & editors:
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
&: Michigan Tech. U.