||It has been suggested that this article be merged into Terminator (solar). (Discuss) Proposed since September 2013.|
Due to the angle at which sunlight strikes this portion of the moon, shadows cast by craters and other geological features are elongated, thereby making such features more apparent to the observer. This phenomenon is similar to the lengthening of shadows on Earth when the sun is low in the sky. For this reason, much lunar photographic study centers on the illuminated area near the lunar terminator, and the resulting shadows provide accurate descriptions of the terrain.
Lunar terminator illusion
The lunar terminator (or tilt) illusion is an optical illusion arising from the erroneous expectation of an observer on Earth that the direction of light illuminating the moon (i.e. a line perpendicular to the terminator) should correspond with the position of the sun in the sky or a sun which has set, when it does not appear to do so. The cause of the illusion is simply the observer is not taking into account that the observed slope of a light ray will change across the sky because of the lack of visual clues to establish 3D perspective.
In popular culture
The lunar terminator features as a plot element in the animated series "Futurama", season 1, episode 2.
- List of basic lunar features
- The lunar day cycle is 29.53 Earth days in length (see ), so the terminator moves across the lunar surface at 15.4 kilometers per hour.
- Jones, Christopher B (January 2014). "Lunar Terminator Illusion". Ellipsis: unfinished thought…. Retrieved 21 May 2016.
- Myers-Beaghton, Andrea K; Myers, Alan L, The Moon Tilt Illusion (PDF)