When pictures were going to be taken of the Great Dark Spot again in November 1994 by the Hubble Space Telescope , it had gone away completely , leaving astronomers to believe that it had either been covered up or that it had just disappeared . When the spot was to be photographed again in November 1994 by the Hubble Space Telescope , it had disappeared completely , leaving astronomers to believe that it had either been covered up or vanished .