Earth's Moon
- Diameter: 3,476 km (2,160 mi)
- Shortest Distance from Earth: 356,399 km (221,456 mi)
- Longest Distance from Earth: 406,699 km (252,711 mi)
- Revolution Around Earth: 27.322 Earth days
- Length of Day and Night: 15 Earth days
- Temperature at Equator: 127°C to 173°C (260°F to -280°F)
- Atmosphere: Little or none
Phases
- New Moon: The dark side of the Moon faces Earth.
- Waxing Crescent: As the Moon moves eastward away from the Sun, a little sunlight appears on it in a crescent shape.
- First Quarter: The waxing increases until one-half of the Moon can be seen.
- Waxing Gibbous: More than half of the Moon is lit, and waxing.
- Full Moon: All of the lit side of the Moon faces Earth.
- Waning Gibbous: A crescent of the Moon is in darkness.
- Third Quarter: The waning increases until one-half of the Moon cannot be seen.
- Waning Crescent: Only a crescent of the Moon is now lit.
Lunar Eclipse
During the phase of full moon, the Moon passes on the opposite side of Earth as the Sun is. If the Moon passes into Earth's shadow, an eclipse occurs. When all of it passes through the umbra, there is a total eclipse. When it passes through only the penumbra, it is a penumbral eclipse. When only a part of it passes through the umbra, it is a partial eclipse.
Danjon Scale
This is a scale for the brightness of the Moon during total lunar eclipses. The letter "L" stands for luminosity.
- L=0 Very dark -- The Moon hardly visible, especially near midtotality
- L=1 Dark -- Grey to brown -- Details on the disk hardly discernible
- L=2 Dark red or rust-coloured -- A dark area in the centre of the shadow, with the edge brighter
- L=3 Brick red -- The shadow often bordered with a bright yellow edge
- L=4 Orange or copper-coloured -- Very bright, with a bright blish edge
Saros Effect
The Babylonians were aware that eclipses of the Moon repeated every eighteen years eleven days. This is known as the saros effect. During similar periods, there are other cycles involving the Moon in a nearly exact multiple of this one. However, successive lunar eclipses in the same saros will actuallyoccur eight hours later and 120° farther west. After three cycles, the eclipse will return to the original place.
