A lunar eclipse takes place when the Earths shadow covers all or part of the Moon. If the Moon had an absolutely flat orbit, every full moon would be a lunar eclipse. The eclipse on May 5, 2023, is the last kind of eclipse where only the lighter part of the shadow will cover the Moon, which is why it is understood as a penumbral lunar eclipse.
The next lunar eclipse will be Oct. 28, 2023, and will be a partial eclipse noticeable mainly in Africa, Europe, and Asia. The Americas will have their own penumbral eclipse on March 25, 2024, followed by a partial lunar eclipse on Sep. 18, 2024.
A lunar eclipse happens when the Moon goes through the Earths shadow. Credit: Sagredo/Wikimedia Commons
How do eclipses work?
Both solar and lunar eclipses depend on particular orientations of the Earth, Sun, and Moon. A lunar eclipse occurs when the Earths shadow covers all or part of the Moon. This can only take place when the Moon is straight on the opposite side of the Earth from Sun, which is also when moons occur.
If the Moon had an absolutely flat orbit, every moon would be a lunar eclipse. However the Moons orbit is slanted by about 5 degrees relative to Earths orbit of the Sun. Because of this small tilt, many of the time a complete moon winds up a little above or listed below the shadow cast by the Earth.
When the Moon is opposite the Sun, lunar eclipses can only occur throughout a full moon. Credit: Orion 8/Wikimedia Commons, CC BY-SA
But two times in each monthlong lunar orbit, the Moon crosses through the exact same horizontal airplane as the Earth and the Sun. If this occurs during a moon, the Sun, Earth and Moon will form a straight line and the Moon will travel through the Earths shadow, leading to a lunar eclipse.
The Earths shadow
As the Sun shines light on Earth, Earth casts a shadow behind itself. However the darkness of shadows are not always uniform, and the shadow cast by the Earth is no exception.
The rays of light coming from a large, or extended, light– such as the Sun or a flashlight– do not all originated from the precise same location. Given that the Sun is big, there can be rather a distance in between the origin of rays of light heading towards Earth.
The shadow on the wall has a darker center surrounded by a lighter, but still shadowed, external ring, much like the shadow cast by Earth. Credit: User4288/Wikimedia Commons, CC BY-SA
This distinction in place indicates that when Earth blocks the light coming from one part of the Sun, it may not obstruct out light originating from another place on the Sun. This results in parts of Earths shadow that are darker– the darkest part is where all light is blocked, while the lighter parts are due to the fact that some light still makes it past the Earth.
A total lunar eclipse is when the Moon passes completely through the darkest part, or umbra, of the Earths shadow. When the umbra covers part of the Moon, a partial lunar eclipse is. The eclipse on May 5, 2023, is the last type of eclipse where just the lighter part of the shadow will cover the Moon, which is why it is called a penumbral lunar eclipse.
The lunar eclipse on May 5, 2023, will show up for the majority of Africa, Asia, Europe and Australia. Credit: NASA
How can you see the lunar eclipse?
As long as you are on the night side of the Earth when a lunar eclipse occurs, you can see it. The May 5 penumbral eclipse will show up in the majority of Europe and Africa at moonrise, Asia and Australia will have the ability to see the whole of the event in the middle of the night, and areas throughout the Pacific Ocean will have the ability to see it at moonset.
Lunar eclipses are relatively brief, just lasting a couple of hours from start to finish. Totality, the part of the eclipse that is darkest, lasts about 30 to 60 minutes depending on how near the center of the shadow you are.
For individuals in North and South America where the eclipse wont be noticeable, there will be plenty more in the next couple of years. The next lunar eclipse will be Oct. 28, 2023, and will be a partial eclipse visible mostly in Africa, Europe, and Asia. The Americas will have their own penumbral eclipse on March 25, 2024, followed by a partial lunar eclipse on Sep. 18, 2024.
For those hoping to catch the next overall lunar eclipse, they will need to wait up until March 14, 2025, when an overall lunar eclipse will be noticeable from the Americas, western Europe and western Africa.
Composed by Shannon Schmoll, Director of the Abrams Planetarium, Michigan State University.
This article was first published in The Conversation.
Penumbral lunar eclipses slightly darken the Moon. Credit: H. Raab/Wikipedia Commons, CC BY-SA
On May 5, 2023, people worldwide will witness a lunar eclipse when the Earth gets in between the Sun and the Moon and casts part of its shadow on the Moon.
The eclipse will be noticeable in Africa, Asia, Australia and large portions of Europe, though not in the U.S. this time around. This eclipse is not what some call a “blood moon,” as it will not redden. Rather, the Moon will dim slightly as it travels through a lighter part of the Earths shadow– called the penumbra.
I am the director of the Abrams Planetarium at Michigan State University and it becomes part of my job to get individuals outside and looking up, and eclipses are some of the simplest to see. While the upcoming occasion will not be the most spectacular celestial display screen, it is simply the very first of a variety of eclipses occurring over the next year, and they all operate in similar ways.
