Lunar Eclipses and the Moon's Orbit

Initially viewed from overhead, the Moon orbits the Earth until it appears to enter the Earth's shadow. The view then rotates down into the ecliptic plane, showing that the tilt of the Moon's orbit causes it to miss the Earth's shadow. The movie fast-forwards several months, showing the rotation of the Moon's orbital plane with respect to the Sun, until the Moon really does enter the Earth's shadow.

Viewed from overhead (the ecliptic north pole), the shadows of the Moon and Earth first align for a lunar eclipse, then a solar eclipse two weeks later. An inset shows what the Moon looks like during and between these events.

Viewed from an increasingly oblique angle approaching the axis of the Earth's shadow, the Moon enters the shadow, producing a total lunar eclipse.

An illustration of the Moon's orbit and the resulting phases. The scale of the Moon and Earth are greatly exaggerated.

This cartoon shows the Moon turning red as it passes through the Earth's shadow. The frames include an alpha channel. They are designed to be combined with a backdrop that shows the geometry of the umbra and penumbra.