What Is a Lunar Eclipse?

A lunar eclipse occurs when Earth passes between the Moon and the Sun, causing Earth’s shadow to fall across the Moon. This natural phenomenon can only happen during a full moon and, depending on the type of eclipse, can cause the Moon to dim or appear red.

Unlike a solar eclipse, which requires protective eyewear to view safely, a lunar eclipse is completely safe to watch with the naked eye. Lunar eclipses can be seen from anywhere on the night side of Earth where the Moon is above the horizon, although visibility can be affected by weather conditions.

What Causes a Lunar Eclipse?

A lunar eclipse happens when the Earth blocks sunlight from reaching the Moon. This occurs only during a full moon when:

• The Sun, Earth, and Moon align in a straight line.
• The Earth’s shadow is cast on the Moon.
• The moon passes through the umbra (total or partial eclipse) or the penumbra (penumbral eclipse).

How Often Do Lunar Eclipses Occur?

Lunar eclipses occur regularly, but they are not visible from every location each time. Because a lunar eclipse can be seen from much of the night side of Earth, people in a particular location generally have more opportunities to see lunar eclipses than total solar eclipses.

The exact type and visibility of each lunar eclipse depend on the alignment of the Sun, Earth and Moon.

A Total Lunar Eclipse in Iceland in 2025

Iceland experienced a total lunar eclipse on March 14, 2025. In Reykjavík, the eclipse began with the penumbral phase at 03:57, totality began at 06:26, and maximum eclipse occurred at 06:58.

The Moon was low in the western sky during totality, making an unobstructed view toward the west important for observers in Reykjavík.

The March 2025 eclipse provides a useful example of the different stages of a total lunar eclipse, from the subtle penumbral phase to the Moon entering Earth’s darker umbral shadow.

Viewing a Lunar Eclipse in Iceland

A lunar eclipse does not require dark skies in the same way as the northern lights or other faint astronomical phenomena. The Moon is bright enough to be viewed from cities as well as rural areas.

For the best experience, find a location with a clear view of the Moon and check the weather forecast beforehand. Binoculars or a telescope are not required, although they can provide a closer look at changes across the lunar surface.

Perlan’s elevated location on Öskjuhlíð offers panoramic views across Reykjavík and the surrounding sky, while its exhibitions and planetarium provide opportunities to learn more about astronomy and Icelandic nature.