Penumbral lunar eclipse of May 2023 | what is this phenomenon, when will it occur and how to see it?

The passage of the Moon through the shadow of the Earth will give us this Friday a wonderful, albeit subtle, astronomical spectacle: a penumbral lunar eclipse.

That is to say, the Moon crosses the penumbra of the Earth, the weakest part of the shadow, so instead of “disappearing” in the sky it will be significantly darkened, giving the sensation that it changes color.

It is not what some call a “blood moon”, since in the penumbral eclipse the Moon does not look red, as Shannon Schmoll, director of the Abrams Planetarium at Michigan State University (MSU) clarifies in an article published by The Conversation .

The moon during a penumbral eclipse visible in Chile in January 2019.

Credit: By Luis Rojas M – Own work, CC BY-SA 4.0,

What is a penumbral lunar eclipse?

Twice a month, the Moon’s orbit places it in the same plane as Earth and the Sunand when this happens with a full moon, then what we know as a lunar eclipse occurs: the shadow of the planet is projected onto the satellite.

What happens is that the enormous size of the Sun means that the shadow cast by the Earth is not uniform: it has a darker nucleus where all the light is blocked, umbra, and areas where the sun’s rays partially reach, the penumbra.

Depending on where the Moon passes through, lunar eclipses can be classified as ‘partial’ (only a part of the satellite passes through the umbra), ‘total’ (the entire moon is completely within the umbra) and ‘penumbral’, which As its name indicates, it occurs when it crosses only the penumbra. Of the latter type is this eclipse.

The penumbral eclipse is one of the most subtle of these phenomena, according to Fred Espenak, a retired NASA scientist, on the EarthSky site.

“These types of eclipses are so subtle that they can go unnoticed by many people,” he says.

Is it dangerous to watch a penumbral lunar eclipse?

Lunar eclipses are short, It doesn’t take a few hours from start to finishand at their peak they are between 30 and 60 minutes.

Schmoll explains that it’s okay to watch a penumbral lunar eclipse when you’re on the night side of Earth.

Where can the eclipse be seen?

The eclipse can be seen from Africa, Asia, Australia and much of Europe during the night of this Friday, May 5, and the early hours of this Saturday, May 6, according to the EarthSky site.

People living in the Americas will not be able to see the eclipse because it will occur during the day in this part of the world.

When can a lunar eclipse be seen in the United States?

Although this Friday’s eclipse will not be visible on the American continent, of course it is not the last.

Those who live in America will be able to see a lunar eclipse on October 28, and on March 25, 2024 they will witness another penumbral eclipse like the one this Friday.

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