There is an eclipse of the Moon when the Moon enters in the umbra or penumbra of the Earth. Contrary to solar eclipses during which the Sun isn’t obscured but occulted by the Moon, the lunar eclipses show the lack of illumination of the Moon for which the Sun is hidden by the Earth. For an observer located on the Moon’s surface, there is an eclipse of the Sun. The Sun, the Earth and the Moon are then almost aligned, and we are at the New Moon. If the orbital plane of the Moon was the same as of the Earth (Ecliptic), then we would have an eclipse of the Moon on each Full Moon, but the Moon’s orbital plane is tilted by 5° 17′ from the Earth’s orbital plane at the Full Moon. The intersection of those two planes is a line called line of nodes and the intersections between this line and the Ecliptic are called node of the Moon’s orbit. To have an eclipse, the Moon must be near the line of nodes during the Full Moon. There are total, partial and penumbral eclipses of the Moon. There is a total eclipse when the Moon is totally inside the umbra of the Earth and a partial eclipse when only part of Moon is inside the umbra of the Earth. Finally, a penumbral eclipse of the Moon is when no point of the Moon is inside the Earth’s umbra and all or some part of the Moon is inside the penumbra of the Earth, meaning that from the Moon we can view only a partial eclipse of the Sun. The solar eclipses predate or follow the lunar eclipses by 14 about days. To compute all the dates and types of eclipses of the Moon, a lunar eclipse calculator is available for your own use. A time exposure calculator is there to help you choose your camera settings. Those who want to concentrate on observing the event visually can rely on Lunar Eclipse Maestro to automatically take pictures for them.
This application controls up to 4 USB, Firewire or Ethernet connected DSLR and CCD cameras during a lunar eclipse, so that you can be free to concentrate on observing the event visually. This brief overview will let you know more.