Celestial phenomena: The “blue moon” meets the super moon

Two celestial phenomena converge tonight: there is a “blue moon” and a supermoon. How often does this happen? Does Earth’s satellite really glow blue?

Thursday night coincides with two celestial phenomena, the so-called “blue moon” and the giant moon. However, a “blue moon” is not a space scene in which Earth’s satellite glows blue. Rather, the term refers to the phenomenon of seeing the full moon twice within one month.

A shorter lunar cycle

This happens on average every two to three years. Because the lunar cycle lasts 29.5 days, our calendar months range from 28 to 31 days. Because the two cycles do not exactly coincide, every now and then there are two full moons in a calendar month – the second full moon after that is called a “blue moon”. This event last occurred on October 31, 2020, and the next “blue moon” is expected after this year on May 31, 2026.

But where does the name come from? “The term originated in America in the nineteenth century,” explains Markus Bruggen, an astrophysicist at the Hamburg Observatory. tagesschau.de. “However, at that time it meant something else, namely four full moons in one season.” But in the twentieth century, the meaning also changed due to the advent of a trade magazine.

The moon appears seven percent larger

On Thursday night, the “blue moon” also becomes a giant moon at the same time: In this phenomenon, the moon, whose orbit is slightly elliptical, approaches Earth in particular at a distance of about 363,300 km, according to the US space agency. NASA. It is usually about 380,000 km away on average, and at its farthest point it reaches 405,000 km. Therefore, the full moon appears slightly larger than on other full moon nights, and it can also have a stronger effect on the tides due to its gravitational pull.

“Tonight the moon appears to be about seven percent larger than usual,” Bruggen explains. This also makes it look a bit brighter. You can catch the spectacle anywhere in Germany – if the weather is right. “The moon is always at its most beautiful when it is near the horizon, shortly after sunset or shortly before sunrise.”

According to Bruggen, a “blue moon” and a supermoon are not uncommon phenomena in and of themselves. “But the fact that the two things coincide only happens once every ten years. So you can definitely take a look at it.”