| Term: | Lunar eclipses |
| Definition: |
The darkening of the Moon which occurs when the Moon enters the umbra of the Earth's shadow. This phenomenon can occur only when the full Moon is near one of the lunar nodes of its orbit around the Earth. There will be a total eclipse if the entire Moon enters the umbra, otherwise the eclipse will be partial when the Moon is somewhat to the north or south of the node and does not cross the shadow entirely. During the eclipse the Moon looks more or less dark, depending especially on the transparency of the Earth's atmosphere. The refraction of Sun's light through the atmosphere sometimes gives a red color to the eclipsed Moon. Colored fringes can be seen around the shadow edge during partial eclipses. Because an eclipse of the Moon is due to the cutting off of the Sun's light, it is visible from the entire hemisphere where the Moon is above the horizon. The maximum duration of a total lunar eclipse, when the Moon passes through the shadow centrally, is 1h 47m. |