The Mainichi Shimbun answers some common questions readers may have about the mechanisms behind lunar and solar eclipses, as well as how often they can be observed here in Japan.

Question: There was a lunar eclipse recently. I've also seen a solar eclipse before, but which one is rarer?

Answer: Both are rare, but on a global scale, solar eclipses occur more frequently. However, in terms of how often they're visible from where people live, lunar eclipses are more commonly seen.

Q: Why is that?

A: To understand this, it's important to know how lunar and solar eclipses work. Both Earth and the moon cast shadows when illuminated by the sun. A lunar eclipse occurs when the moon enters Earth's shadow, while a solar eclipse happens when the moon's shadow falls on the Earth. However, since the moon's orbit around Earth is slightly tilted relative to Earth's orbit around the sun, the three bodies rarely align perfectly to cause an eclipse.

Q: Why do solar eclipses occur more often?

A: Both lunar and solar eclipses occur when the moon is within a certain range from Earth along its orbit. This range is broader for solar eclipses than for lunar eclipses, making solar eclipses more likely to occur.

Q: But lunar eclipses are seen more often, right?

A: Yes, that's because lunar eclipses can be observed over a wider area. They are visible from the entire night side of Earth, which covers about half of the planet. In contrast, the area where a solar eclipse can be seen is limited. This is because the moon's radius is about one-fourth that of Earth's, and with the moon being about 380,000 kilometers away, the shadow it casts on Earth is quite small.

In fact, during the decade from 2021 to 2030, there will be 22 solar eclipses and 16 lunar eclipses. However, in Japan, solar eclipses will be visible only twice, compared to 11 times for lunar eclipses.

Q: When will the next ones be visible in Japan?

A: The next lunar eclipse visible in Japan will take place on March 3, 2026. It will be a total lunar eclipse, where the moon is completely within Earth's shadow. Meanwhile, the next solar eclipse will occur on June 1, 2030. Most of Hokkaido will witness an annular solar eclipse, where a ring of light remains visible, while other regions will see a partial solar eclipse.

(Japanese original by Satoshi Kondo, Lifestyle, Science & Environment News Department)

How do lunar and solar eclipses work, and when will the next one be visible in Japan?