Voyager 2 made its closest approach to Neptune, it performed a close fly-by of Triton, the larger of Neptune's two originally known moons, passing within about . Voyager 2 discovered previously unknown Neptunian rings, and confirmed six new moons: Despina, Galatea, Larissa, Proteus, Naiad and Thalassa. While in the neighborhood of Neptune, Voyager 2 discovered the "Great Dark Spot", which has since disappeared, according to observations by the Hubble Space Telescope. The Great Dark Spot was later hypothesized to be a region of clear gas, forming a window in the planet's high-altitude methane cloud deck. With the decision of the International Astronomical Union to reclassify Pluto as a dwarf planet in 2006, the flyby of Neptune by Voyager 2 in 1989 retroactively became the point when every known planet in the Solar System had been visited at least once by a space probe. Interstellar mission Once its planetary mission was over, Voyager 2 was described as working on an interstellar mission, which NASA is using to find out what the Solar System is like beyond the heliosphere. Voyager 2 is currently transmitting scientific data at about 160 bits per second. Information about continuing telemetry exchanges with Voyager 2 is available from Voyager Weekly Reports. In 1992, Voyager 2 observed the nova V1974 Cygni in the far-ultraviolet. In July 1994, an attempt was made to observe the impacts from fragments of the comet Comet Shoemaker–Levy 9 with Jupiter. The craft's position meant it had a direct line of sight to the impacts and observations were made in the ultraviolet and radio spectrum. Voyager 2 failed to detect anything, with calculations showing that the fireballs were just below the craft's limit of detection. On November 29, 2006, a telemetered command to Voyager 2 was incorrectly decoded by its on-board computer—in a random error—as a command to turn on the electrical heaters of the spacecraft's magnetometer. These heaters remained turned on until December 4, 2006, and during that time, there was a resulting high temperature above , significantly higher than the magnetometers were designed to endure, and a sensor rotated away from the correct orientation. As of this date it had not been possible to fully diagnose and correct for the damage caused to Voyager 2s magnetometer, although efforts to do so were proceeding. On August 30, 2007, Voyager 2 passed the termination shock and then entered into the heliosheath, approximately closer to