Great Dark Spot - wikipedia Great Dark Spot The Great Dark Spot as seen from Voyager 2 The Great Dark Spot ( also known as GDS - 89, for Great Dark Spot - 1989 ) was one of a series of dark spots on Neptune similar in appearance to Jupiter 's Great Red Spot. GDS - 89 was the first Great Dark Spot on Neptune to be observed in 1989 by NASA 's Voyager 2 spaceprobe. Like Jupiter 's spot, Great Dark Spots are anticyclonic storms. However, their interiors are relatively cloud - free, and unlike Jupiter 's spot, which has lasted for hundreds of years, their lifetimes appear to be shorter, forming and dissipating once every few years or so. Based on observations taken with Voyager 2 and since then with the Hubble Space Telescope, Neptune appears to spend somewhat more than half its time with a Great Dark Spot. Almost all that is known about Neptune is based on the research carried out by Voyager 2. Contents 1 Characteristics 2 Disappearance 3 See also 4 References 5 External links Characteristics The dark, elliptically - shaped spot ( with initial dimensions of 13,000 × 6,600 km, or 8,100 × 4,100 mi ) of GDS - 89 was about the same size as Earth, and was similar in general appearance to Jupiter 's Great Red Spot. Around it, winds were measured blowing up to 2,400 kilometers ( 1,500 mi ) an hour, the fastest in the Solar System. The Great Dark Spot is thought to represent a hole in the methane cloud deck of Neptune. The spot was observed at different times with different sizes and shapes. The Great Dark Spot generated large white clouds at or just below the tropopause layer similar to high - altitude cirrus clouds found on Earth. Unlike the clouds on Earth, however, which are composed of crystals of ice, Neptune 's cirrus clouds are made up of crystals of frozen methane. And while cirrus clouds usually form and then disperse within a period of a few hours, the clouds in the Great Dark Spot were still present after 36 hours, or two rotations of the planet. Neptune 's dark spots are thought to occur in the troposphere at lower altitudes than the brighter upper cloud deck features. As they are stable features that can persist for several months, they are thought to be vortex structures. Disappearance Dark spot on Neptune full color ( left ) and blue light ( right ). 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 has either been covered up or vanished. The persistence of companion clouds shows that some former dark spots may continue to exist as cyclones even though they are no longer visible as a dark feature. Dark spots may dissipate when they migrate too close to the equator, or possibly through some other unknown mechanisms. However, in 2016 an almost identical spot emerged in Neptune 's northern hemisphere. This new spot, called the Northern Great Dark Spot ( NGDS ), has remained visible for several years. It is unknown whether this spot is still present on the planet, as observations using the Hubble telescope are limited. See also Dragon Storm ( astronomy ) Extraterrestrial cyclone Great Red Spot Oval BA Small Dark Spot References Jump up ^ Hammel, H.B. ; Lockwood, G.W. ; Mills, J.R. ; Barnet, C.D. ( 1995 ). `` Hubble Space Telescope Imaging of Neptune 's Cloud Structure in 1994 ''. Science. 268 ( 5218 ) : 1740 -- 1742. Bibcode : 1995Sci... 268.1740 H. doi : 10.1126 / science. 268.5218. 1740. PMID 17834994. Jump up ^ Stratman, P.W. ; Showman, A.P. ; Dowling, T.E. ; Sromovsky, L.A. ( 2001 ). `` EPIC Simulations of Bright Companions to Neptune 's Great Dark Spots '' ( PDF ). Icarus. 151 ( 2 ) : 275 -- 285. Bibcode : 1998Icar... 132... 239L. doi : 10.1006 / icar. 1998.5918. Retrieved 2008 - 02 - 26. Jump up ^ Gibbard, S.G. ; de Pater, I. ; Roe, H.G. ; Martin, S. ; Macintosh, B.A. ; Max, C.E. ( 2003 ). `` The altitude of Neptune cloud features from high - spatial - resolution near - infrared spectra '' ( PDF ). Icarus. 166 ( 2 ) : 359 -- 374. Bibcode : 2003Icar... 166... 359G. doi : 10.1016 / j. icarus. 2003.07. 006. Retrieved 2008 - 02 - 26. Jump up ^ Max, C.E. ; Macintosh, B.A. ; Gibbard, S.G. ; Gavel, D.T. ; Roe, H.G. ; de Pater, I. ; Ghez, A.M. ; Acton, D.S. ; et al. ( 2003 ). `` Cloud Structures on Neptune Observed with Keck Telescope Adaptive Optics ''. The Astronomical Journal. 125 ( 1 ) : 364 -- 375. Bibcode : 2003AJ... 125... 364M. doi : 10.1086 / 344943. Jump up ^ `` Dark spot on Neptune ''. Retrieved 28 June 2016. Jump up ^ Sromovsky, L.A. ; Fry, P.M. ; Dowling, T.E. ; Baines, K.H. ( 2000 ). `` The unusual dynamics of new dark spots on Neptune ''. Bulletin of the American Astronomical Society. 32 : 1005. Bibcode : 2000DPS... 32.0903 S. Jump up ^ `` Neptune ''. SolarViews.com. Retrieved 2011 - 09 - 28. Jump up ^ `` Hubble Discovers New Dark Spot on Neptune ''. newscenter. Retrieved 2016 - 02 - 04. Jump up ^ `` Dark Spots in Our Knowledge of Neptune ''. nytimes. Retrieved 2016 - 02 - 04. External links Wikimedia Commons has media related to Great Dark Spot. Neptune 's Great Dark Spot of 1989, Windows to the Universe Neptune 's Great Dark Spot : Gone But Not Forgotten, Astronomy Picture of the Day, May 8, 1996 Neptune Outline of Neptune Geography Great Dark Spot Small Dark Spot Rings Moons Despina Galatea Halimede Laomedeia Larissa Naiad Nereid Neso Proteus Psamathe Sao S / 2004 N 1 Thalassa Triton Astronomy Discovery Urbain Le Verrier Johann Gottfried Galle John Couch Adams Heinrich Louis d'Arrest William Lassell General Kuiper belt Neptune - crossing minor planets Trojans 2001 QR 2004 KV 2004 UP 2005 TN 2005 TO 2006 RJ 2007 VL 2008 LC 2011 HM Exploration Past Voyager 2 ( 1989 flyby ) Proposals ODINUS Triton Hopper Argo Cancelled Mariner Mark II Neptune Orbiter New Horizons 2 Related Fiction Mythology Book Portal Retrieved from `` https://en.wikipedia.org/w/index.php?title=Great_Dark_Spot&oldid=852581551 '' Categories : Neptune Planetary spots Vortices Talk Contents About Wikipedia Azərbaycanca Беларуская Български Català Čeština Español Euskara فارسی Français Galego 한국어 Հայերեն Bahasa Indonesia Italiano עברית Nederlands 日本 語 Norsk Polski Português Русский Simple English Српски / srpski Suomi Svenska Türkçe Українська 中文 20 more Edit links This page was last edited on 30 July 2018, at 00 : 13 ( UTC ). 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Question: what happened to the great dark spot on neptune
Answer: either been covered up or vanished