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The Crater Illusion also known as the Crater/Dome Illusion or Dome Illusion is an optical illusion which causes Impact craters in some images to appear as domes or mountains. It is believed to be caused by our being accustomed to seeing light from overhead.〔(Crater Illusion by Paul Doherty ), retrieved September 12, 2015〕 When some images are taken from orbit, the light from the sun is nearly horizontal. This is the only time shadows are seen. Our brains are tricked into thinking that the interior of the crater is above the surrounding terrain instead of below it. ==Examples== In September 2015, NASA released the image on the left from the space probe Dawn of the crater Occator on Saturn's moon Ceres. Because of the position of the Sun at the time the image was taken, the walls of the crater may appear to be convex instead of concave. On the right is the same image roated 180-degrees to change the position of the shadows and eliminate the illusion. In December 1968, the Apollo 8 mission took the photograph on the right of the Moon's crater Goclenius. On the left is the same image rotated in an attempt to create the illusion. In March 2011, NASA released an image of Mercury's Spitteler and Holberg craters taken by the MESSENGER spacecraft. The image on the left is the original image and the image on the right is the same image rotated in an attempt to remove the illusion. In the image on the left of the Tin Bider crater produced by NASA Earth Observatory's EO-1-based Avanced Land Imager produces a reverse illusion. The crater rises above the surrounding terrain, however the position of the sun makes it appear to be below it.〔(Tin Bider Crater, Algeria from the NASA Earth Observatory ), retrieved September 12, 2015〕 ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Crater Illusion」の詳細全文を読む スポンサード リンク
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