What is Great Dark Spot?
[[Image:Neptune darkspot.jpg|thumbnail|200px|The Great Dark Spot as seen from [[Voyager 2]].]] The '''No. 1989 Great Dark Spot''' (also known as '''GDS-89'''<ref>{{cite journal | title=Hubble Space Telescope Imaging of Neptune's Cloud Structure in 1994 | journal=Science | year=1995 | volume=268 | issue=5218 | pages=1740–1742 | doi=10.1126/science.268.5218.1740 | pmid=17834994 | s2cid=11688794 | last1=Hammel | first1=H. B. | last2=Lockwood | first2=G. W. | last3=Mills | first3=J. R. | last4=Barnet | first4=C. D. | bibcode=1995Sci...268.1740H }}</ref>) was a dark spot on [[Neptune (planet)|Neptune]] similar in appearance to [[Jupiter (planet)|Jupiter's]] [[Great Red Spot]]. It was discovered in 1989 by [[NASA]]'s ''[[Voyager 2]]'' probe. Although it appears similar to Jupiter's spot, which is an [[anticyclonic storm]] (this is like a [[hurricane]]), it is believed that the Great Dark Spot is an [[atmospheric]] hole similar to the hole in [[Earth|Earth's]] [[ozone layer]]. However, the insides of Great Dark Spots are mostly cloud-free, and unlike Jupiter's spot, which has lasted for hundreds of years, their lifetimes appear to be much shorter, forming and disappearing once every few years or so. Based on pictures taken by Voyager and since then with the [[Hubble Space Telescope]], Neptune appears to spend a little bit more than half its time with a Great Dark Spot. ==Characteristics== The dark, [[ellipse|elliptically]]-shaped spot (with initial dimensions of 13,000 × 6,600&nbsp;km, or 8,100 × 4,100&nbsp;mi) was about the same size as [[Earth]], and was similar looking to [[Jupiter]]'s [[Great Red Spot]]. Around the Great Dark Spot, winds were measured blowing up to 2,400 [[Km|kilometers]] (1,500 miles) an hour, the fastest in the Solar System. The Great Dark Spot is thought to be a hole in the [[methane]] cloud deck of [[Neptune]]. The spot was seen at different times with different sizes and shapes. The Great Dark Spot generated large white clouds at or just below the [[tropopause]] layer<ref>{