A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). This can occur only when the sun, Earth and moon are aligned (in "syzygy") exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can occur only the night of a full moon. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes.
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 the Earth. A lunar eclipse lasts for a few hours, whereas a total solar eclipse lasts for only a few minutes at 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. For the date of the next eclipse see the section Recent and forthcoming lunar eclipses.
A supermoon is the coincidence of a full moon or a new moon with the closest approach the Moon makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth. The technical name is the perigee-syzygy of the Earth-Moon-Sun system. The term "supermoon" is not astronomical, but originated in modern astrology.
The association of the Moon with both oceanic and crustal tides has led to claims that the supermoon phenomenon may be associated with increased risk of events such as earthquakes and volcanic eruptions, but the evidence of such a link is widely held to be unconvincing. The most recent occurrence will be on September 28, 2015. The opposite phenomenon, an apogee-syzygy, has been called a micromoon, though this term is not as widespread as supermoon.
Blood moon - Due to its reddish color, a totally eclipsed moon is sometimes referred to as a "blood moon. [16] In addition, in the 2010s the media started to associate the term "blood moon" with the four full moons of a lunar tetrad, especially the 2014–2015 tetrad coinciding with the feasts of Passover and Tabernacles. A lunar tetrad is a consecutive sequence of four lunar eclipses, spaced six months apart.
