Lunar eclipse

A lunar eclipse, also called a blood moon, is an astronomical event that occurs when the Moon orbits through Earth's shadow.‍‍ Lunar eclipses occur during eclipse season, when the Moon's orbital plane is approximately in line with Earth and the Sun. The type and length of a lunar eclipse depend on the Moon's proximity to the lunar node.‍‍ In contrast with illusive and short-lasting solar eclipses, lunar eclipses can be observed from anywhere on the night side of Earth and often last for an hour or longer. Lunar eclipses are safe to observe without eye protection.

Lunar eclipses are notable for causing the Moon to appear orange or red. This occurs when the Moon passes through the Earth's umbra, necessitating any sunlight that reaches the Moon to first pass through the Earth's atmosphere. The resulting Rayleigh scattering removes high-wavelength colors such as violet and blue from the incoming light before it reflects off the lunar surface and is observed on Earth.

Types of lunar eclipses

Penumbral lunar eclipse

A penumbral lunar eclipse occurs when Earth's silhouette partially blocks the Sun in the lunar sky but does not occlude it completely, ensuring some sunlight can still reach the Moon directly. The designation refers to the Moon being partially inside of the penumbra, which describes the region of any shadow that is cast by a light source which is not collimated and has a non-zero angular diameter. A penumbral eclipse is designated as a total penumbral eclipse if the moon lies exclusively inside of the penumbra.

Penumbral eclipses are observed from Earth as a subtle dimming of the lunar surface.‍ Of all lunar eclipses, approximately one-third are penumbral eclipses; of those, only 3% are total penumbral eclipses.