What is a penumbral lunar eclipse?

A penumbral lunar eclipse occurs when the Earth is positioned between the sun and the moon, but only the outer part of Earth's shadow, known as the penumbra, falls on the moon's surface. The penumbra is a fainter, outer part of the Earth's shadow that is in contrast to the darker, inner shadow known as the umbra. During a penumbral lunar eclipse, the moon usually appears slightly darker than usual but it does not completely disappear from sight like in a total lunar eclipse.

Unlike other types of lunar eclipses, penumbral eclipses are more subtle and harder to observe with the naked eye. They also occur more frequently than total or partial lunar eclipses.

Penumbral lunar eclipses can be a fascinating astronomical event for skywatchers and astronomers. They offer a unique opportunity to observe and study the moon's surface and its interaction with the Earth's shadow.

A penumbral lunar eclipse occurs when the Moon passes through the outer part of the Earth's shadow, called the penumbra. This is a much fainter shadow than the inner part of the Earth's shadow, called the umbra, so penumbral lunar eclipses are often difficult to see.

The penumbra is the outer part of the Earth's shadow, and it is formed when the Earth's atmosphere bends sunlight around the edge of the planet. The penumbra is much fainter than the umbra, because the sunlight that passes through the atmosphere is scattered in all directions. This means that only a small amount of sunlight reaches the Moon when it is in the penumbra.

Penumbral lunar eclipses can occur when the Moon is anywhere between 97% and 100% full. This is because the Earth's shadow is much larger than the Moon, and the Moon can pass through the penumbra even if it is not perfectly aligned with the Sun and the Earth.

Penumbral lunar eclipses are usually very subtle, and they can be difficult to see with the naked eye. However, they can be seen with binoculars or a telescope. If you see a penumbral lunar eclipse, you will notice that the Moon appears to be slightly darker than usual. This is because the Moon is receiving less sunlight when it is in the penumbra.

Penumbral lunar eclipses are relatively common, and they can occur several times per year. The next penumbral lunar eclipse will occur on April 25, 2023.