Topic summary
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 elusive 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 cause the Moon to appear orange or red. This occurs because when the Moon passes through the Earth's umbra, any sunlight that reaches the Moon must first pass through the Earth's atmosphere. The resulting Rayleigh scattering removes short-wavelength colors such as violet and blue from the light before it reflects back off the lunar surface and is observed on Earth.