The Earth casts a long shadow into space, and when this shadow passes over the Moon it can cause an eclipse.
A lunar eclipse can only happen during a full Moon, when the Sun is directly behind the Earth. It happens only occasionally, because the orbit of the Moon is slightly tilted and so the shadow usually misses it. Lunar eclipses can last for over one hour, but they do not completely black out the shadowed part of the Moon. Some sunlight always filters through, making the shadow look a reddish-brown colour. Eclipses can only be seen from certain parts of the world.
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Fact File: The distance of the Moon away from the Earth was settled once and for all after the Apollo astronauts left a small reflector on the Moon’s surface. This distance is 384,000 km, though it varies slightly because the Moon does not have a perfectly circular orbit. |
Picture Credit : Google