Do Lunar Eclipses Occur?

Lunar eclipses can only happen when the Moon is opposite the Sun in the sky, a monthly occurrence we know as a full Moon. But lunar eclipses do not occur every month because the Moon's orbit is tilted five degrees from Earth's orbit around the Sun. Without the tilt, lunar eclipses would occur every month.

When can lunar eclipses occur?

A lunar eclipse occurs when the Moon moves into the Earth's shadow. This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned (in syzygy) with Earth between the other two, and only on the night of a full moon.

How often do lunar eclipses occur?

On average, there are two lunar eclipses each year, although Potempa notes that this can vary. "Eclipses only occur during two eclipse seasons per year, which are about six months apart," she explains.