Eclipse

An eclipse is an astronomical event that occurs when an astronomical object or spacecraft is temporarily obscured by passing into the shadow of another body, or by having another body pass between it and the viewer, an alignment called a syzygy. A solar eclipse occurs when the Moon passes between the Earth and the Sun and blocks sunlight, and includes total eclipses where the Moon completely covers the Sun, annular eclipses where the Moon is too distant to fully cover it, and partial eclipses where the Moon only partly blocks it. A lunar eclipse happens when the Moon enters the shadow of the Earth, and includes penumbral, partial, and total forms depending on how much of the Moon crosses into the umbra. Eclipses occur because the orbital plane of the Moon is tilted relative to the orbital plane of the Earth around the Sun; if both orbits were perfectly circular in the same plane an eclipse would happen every month, but the tilt instead confines eclipses to eclipse seasons that recur roughly twice a year, when the orbital planes and the position of the Sun align enough for the shadow geometry to work.