# lunar eclipse

A lunar eclipse is an astronomical event that occurs when the Moon moves into the shadow of the Earth.  From the Moon's perspective, the Earth is blocking the Sun's light.

Lunar eclipses only occur during a Full Moon.

=> moon_phase.gmi {moon phase}

Every year has at least 2 lunar eclipses and as many as 5 lunar eclipses.

Every lunar eclipse is a part of a "eclipse season", which is a string of solar and lunar eclipses.  For every lunar eclipse, there is a solar eclipse either the New Moon immediately before or immediately after the lunar eclipse.

=> eclipse_season.gmi {eclipse season}
=> solar_eclipse.gmi {solar eclipse}

## Why Isn't Every Full Moon a Lunar Cclipse?

The Moon's orbit around the Earth is not directly in line with the Earth's Equator and the Earth's orbit around the Sun is not directly in line with the Earth's Equator.  The Moon orbits the Earth at about a 5 degree angle and the Earth orbits the Sun at about a 23.45 degree angle.  These angles along with the orbits being out of phase with each other allows the Sun and Moon to pass above and below each other in the sky.

## Types of Lunar Eclipses

### Penumbral

A penumbral lunar eclipse occurs when part or all of the Moon is within the Earth's penumbra and no part of the Moon is within the Earth's umbra.  The penumbra in this case is all of the points in space where the Sun's light is partially blocked by the Earth but some light from the Sun can still reach.  From the perspective of someone on the Moon in the penumbra, the Sun will appear partially blocked by the Earth.

### Partial

A partial lunar eclipse occurs when part of the Moon is within the Earth's umbra but not all of the Moon.  The umbra in this case is all of the points in space where the Sun's light is completely blocked by the Earth.  From the persepective of someone on the Moon in the umbra, the Sun will appear completely blocked by the Earth, but at least some point on the Moon must still be in the penumbra, where the Sun will appear only partially blocked by the Earth.

### Total

A total lunar eclipse occurs when the entirety of the Moon is within the Earth's umbra.  From the perspective of someone on the Moon at any point facing the Sun, the Sun will be completely blocked out by the Earth.

## Incoming Wiki Links

=> index.gmi {index}
=> moon_phase.gmi {moon phase}
=> eclipse_season.gmi {eclipse season}
=> solar_eclipse.gmi {solar eclipse}