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: Voyager 2 produced images showing the Great Dark Spot, an 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.