Neptune - Voyager 2 - Neptune has an equatorial diameter of about 49,000 kilometres. Its...

Neptune - Voyager 2 - Neptune has an equatorial diameter of about 49,000 kilometres. Its blue color is due to the abundance of methane in its atmosphere. On this photo, on the left, the Great Dark Spot, which is the size of the Earth where winds are blowing at 300 m/s. This spot has now disappeared but other dark spots have been detected since then. Image of Neptune obtained by the Voyager 2 probe on August 16, 1989. During August 16 and 17, 1989, the Voyager 2 narrow - angle camera was used to photograph Neptune almost continuously, recording approximately two and one - half rotations of the planet. These images represent the most complete set of full disk Neptune images that the spacecraft will acquire. This picture from the sequence shows two of the four cloud features which have been tracked by the Voyager cameras during the past two months. The large dark oval near the western limb (the left edge) is at a latitude of 22 degrees south and circuits Neptune every 18.3 hours. The bright clouds immediately to the south and east of this oval are seen to substantially change their appearances in periods as short as four hours. The second dark spot, at 54 degrees south latitude near the terminator (lower right edge), Neptune circuits every 16.1 hours. This image has been processed to enchance the visibility of small features, at some sacrifice of color fidelity