Eclipses

Eclipses are astronomical alignments that occur when two or more celestial bodies cast shadows onto each other. In the Earth–Moon–Sun system, eclipses take place when the Sun, Moon, and Earth align closely enough that one body blocks light from another, producing a shadow that can be observed from Earth.

Solar eclipses occur at new moon, when the Moon passes between the Sun and Earth. Depending on distances and alignment, observers may experience a total solar eclipse (the Moon's umbra completely covers the Sun), an annular solar eclipse (the Moon is too far from Earth to fully cover the Sun, leaving a bright ring), or a partial solar eclipse (only part of the Sun is obscured). A hybrid solar eclipse changes from total to annular along the path.

Lunar eclipses occur at full moon, when the Earth lies between the Sun and Moon. If the Moon enters Earth's umbra, a total lunar eclipse occurs; if only the penumbra is reached, a penumbral lunar eclipse; if only part enters the umbra, a partial lunar eclipse. Lunar eclipses are typically visible from the night side of Earth and are safe to observe without special equipment.

The geometry of eclipses involves the Moon’s orbit inclined about five degrees to the Sun–Earth line, so eclipses only happen when the Moon is near one of its orbital nodes. Eclipses occur in seasons, with two to five events possible each year. The Saros cycle, roughly 18 years and 11 days, is a periodic pattern used to predict eclipses and their characteristics.