Moon Eclipses

Moon eclipses work according the same mechanism that the eclipses of the Sun. In the case of Moon eclipses, it's the Earth which is screening the Sun to the Moon. Like for the Sun eclipses, celestial mechanics do not provide us with a Moon eclipse at each lunar orbit. Moon eclipses are as rare as solar eclipses. Moon eclipses occur at full moon as, at the opposite of solar eclipses which occur for a part of the Earth only, Moon's eclipses are visible everywhere on Earth, provided to be on the right side, that is on Earth's night side

In the same way that the Sun, during Sun eclipses, is generating three different kinds of shadows through the Moon, it does so through the Earth. Trailing on the other side of the Earth are found an "umbra", an "antumbra", and a "penumbra" (from three Latin words meaning "shadow", opposed to the umbra", and "near umbra"). That is that, at an appropriate location, a theoretical observer would respectively see the Earth entirely masking the Sun there where the "umbra" is (he would see a total Sun eclipse), a ring of Sun surrounding the dark disk of the Earth at the "antumbra" (it would be an annular Sun eclipse), and a Sun partially occulted only in the "penumbra". Due to the configuration of the Earth-Moon system, the "umbra" and the "penumbra" only are involved in a Moon eclipse, as it would need the Moon to be located about 4 times farther from the Earth to see the Earth at a smaller apparent diameter than the Sun

The "umbra" and the "penumbra" determine which kind of Moon eclipse is occuring. If the Moon passes inside the Earth's umbra, it's a total Moon eclipse which occurs. If the Moon passes partly in the Earth's umbra only, it's a partial Moon eclipse occurring. Or when the Moon passes inside the penumbra only, it's a penumbral Moon eclipse

Penumbral Moon eclipses are hard to observe as Moon does not journey across the about 3-lunar diameter-wide Earth's dark "umbra" but in the "penumbra" only (hence the name). As seen from the Moon, such a penumbral eclipse would be seen like a partial solar eclipse, that is that the dimming of the Moon, as seen from Earth, is weak. It's well observable however at the strongest of the penumbral eclipse and before and after the eclipse's greatest, from when the Moon's edge is either midway in, or out, of the penumbra. Partial penumbral eclipses are theoretically possible, but they are barely noticeable

Total Moon eclipses, on the other hand, are a fine show as the Moon is seen harshly carved by the Earth's dark umbra and progressively advancing towards the eclipse's greatest. It's at that moment that the Moon is seen turning into a range of orange-red colors, as a part of Sun light reaches Moon, filtering through the Earth's atmosphere. The Earth's atmosphere lets pass all what is not blue only! Each total eclipse is unique in its colors due to Earth's atmosphere conditions at the moment. There may be, for example, volcanoes dust or a lot of clouds. A total Moon eclipse always begins and ends with a penumbral eclipse

Partial Moon eclipses are just occulting a part of Moon, as, at the eclipse greatest, the red-orange hues may be possibly seen. Partial lunar eclipses are fine show too however as the Moon is seen indented by the dark "umbra" of the Earth

There may be up to 3 lunar eclipses each year (5 including penumbral), or none. There cannot be more than 7 eclipses in any one year, generally: 4 solar and 3 lunar, or 5 solar and 2 lunar (penumbral not included). A Moon eclipse usually precedes, or follows a Sun eclipse by about 2 weeks