• Occurs when any part of the Earth or the Moon enters the shadow of the other
  • The darkest part of the shadow the umbra
  • The lighter, more diffuse region of the shadow is called the penumbra
  • The Moon is usually sufficiently above or below the ecliptic plane to avoid an eclipse
    • The paths cross twice a year

Solar Eclipse

Solar eclipse

Geometry of a total solar eclipse

  • The Moon's shadow covers the Earth and partially hides the Sun
  • Total solar eclipse
    • When the Moon is close to its average distance from the Earth, it can cover the Sun completely
    • Very small area on the Earth
    • Eclipse path travels at 1500 km/hour

Lunar Eclipse

Geometry of a lunar eclipse

Space Astronomy Earth The Moon Sun