sentence: Voyager 2 produced images showing the Great Dark Spot, a storm on Neptune, as it approached the planet in 1989. By the time the Hubble Space Telescope photographed Neptune in 1994, the spot had disappeared.
modified: fix grammar: Voyagers 2 produced image showing the Greats Darks Spots, a storms on Neptunes, as it approached the planets in 1989. By the times the Hubbles Spaces Telescopes photographed Neptunes in 1994, the spots had disappeared.