Lunar eclipses occur when Earth moves between the sun and the moon, casting a shadow across the lunar surface. Lunar eclipses can only take place during a full moon and are a popular event for skywatchers around the world, as they can be enjoyed without any special equipment, unlike solar eclipses. The next lunar eclipse will be a total lunar eclipse on March 13-14, 2025. A lunar eclipse is caused by Earth blocking sunlight from reaching the moon and creating a shadow across the lunar surface. The sun-blocking Earth casts two shadows that fall on the moon during a lunar eclipse: The umbra is a full, dark shadow, and the penumbra is a partial outer shadow. There are three types of lunar eclipses depending on how the sun, Earth and moon are aligned at the time of the event. Total lunar eclipse: Earth's shadow is cast across the entire lunar surface. Partial lunar eclipse: During a partial lunar eclipse, only part of the moon enters Earth's shadow, which may look like it is taking a "bite" out of the lunar surface. Earth's shadow will appear dark on the side of the moon facing Earth. How much of a "bite" we see depends on how the sun, Earth and moon align, according to NASA. Penumbral lunar eclipse: The faint outer part of Earth's shadow is cast across the lunar surface. This type of eclipse is not as dramatic as the other two and can be difficult to see.