<P> A lunar eclipse occurs when the Moon passes directly behind Earth and into its shadow . This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned (in syzygy), with Earth between the other two . A lunar eclipse can occur only on the night of a full moon . The type and length of a lunar eclipse depend on the Moon's proximity to either node of its orbit . </P> <P> During a total lunar eclipse, Earth completely blocks direct sunlight from reaching the Moon . The only light reflected from the lunar surface has been refracted by Earth's atmosphere . This light appears reddish for the same reason that a sunset or sunrise does: the Rayleigh scattering of bluer light . Due to this reddish color, a totally eclipsed Moon is sometimes called a blood moon . </P> <P> Unlike a solar eclipse, which can be viewed only from a certain relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth . A total lunar eclipse lasts a few hours, whereas a total solar eclipse lasts only a few minutes as viewed from any given place, due to the smaller size of the Moon's shadow . Also unlike solar eclipses, lunar eclipses are safe to view without any eye protection or special precautions, as they are dimmer than the full Moon . </P> <P> For the date of the next eclipse, see the section Recent and forthcoming lunar eclipses . </P>

From what portion of the earth can a lunar eclipse be seen