Despite the darkness: Why the moon is not invisible today

Heidelberg. Today, there's a very special celestial spectacle: a total lunar eclipse can be observed from all over Germany. This is assuming, of course, that visibility is clear – and according to a forecast from the German Weather Service (DWD) on Saturday, the sky is looking good. Aside from patchy clouds, the sky will remain clear throughout Sunday. However, cloud cover may become denser in the west and southwest overnight.

The fully illuminated moon moves through the Earth's shadow and is eclipsed in the process. This is because the Earth moves between the moon and the sun on its orbit around the sun, as the German Aerospace Center (DLR) explains. "The moon, Earth, and sun are almost in line, and the Earth's umbra moves across the moon."

It's essentially the same principle as a solar eclipse, where the moon moves between the sun and the Earth. However, because the diameter of the Earth is about four times larger than that of the moon, the same applies to the shadow. The eclipse on the lunar surface therefore lasts longer.

It begins with the Moon entering Earth's penumbra at approximately 5:27 p.m. One hour later, it enters the umbra. Totality begins around 7:30 p.m.

It lasts until about 8:53 p.m. Then the full moon moves out of the umbra before leaving it completely at about 9:57 p.m.

"Unfortunately, this time the lunar eclipse has a huge drawback," says Carolin Liefke, deputy director of the House of Astronomy in Heidelberg. "No matter where it occurs: The moon will rise completely eclipsed." Because it's not an exceptionally large "supermoon," it might be difficult to see directly on the horizon – but only when it's higher in the sky, above the haze. "It's even possible that you won't be able to see it until it's already out of total darkness."

In Berlin, for example, the moon rises at 7:37 p.m., in Munich at 7:40 p.m., in Hamburg at 7:52 p.m., and in Cologne at 8:01 p.m. "The further east you are, the better," says Liefke, referring to the rising.

Some observatories, such as those in Berlin and Stuttgart or the Lake Constance Planetarium in Kreuzlingen near Konstanz, open specifically for this natural spectacle.

The cause is the Earth's atmosphere, as the Darmstadt Public Observatory explains on its website. Sunlight is deflected inward by the air layers of the Earth's atmosphere. The short-wave blue component of sunlight, in particular, is weakened by scattering in the atmosphere. "Thus, the Moon primarily receives the reddish component of the sunlight."

Reddish-brownish. Liefke expects a relatively deep red moon. "That will depend greatly on the local conditions." Smog in big cities or dust stirred up by agriculture could play a role. Above all, however, the moon will not be bright red, Liefke explained. Therefore, she finds the term "copper moon" more apt than the more common "blood moon."

If humans were on the moon during a lunar eclipse, they wouldn't experience complete darkness due to refraction. The reddish light played a less significant role – according to the DLR, the astronauts would experience the spectacle differently: "For them, it would be a solar eclipse caused by Earth – because the sun then disappears behind the dark disk of the Earth," the experts write on their website. "So if we observe a lunar eclipse from Earth, people on the moon simultaneously see a solar eclipse."

Anyone who misses the event now will either have to travel far or wait a few years. On March 3, 2026, a total lunar eclipse will be visible from America and Asia, says Liefke. In Germany, the next opportunity will not be until December 31, 2028.

At least: Next year on August 28th, one can observe at least a partial lunar eclipse from Germany. However, one would have to get up very early in the morning—around 4:30 a.m.—to do so, says Liefke.

For scientists, such a natural spectacle isn't so exciting. "Researchers know what's happening," says Liefke. But it's a beautiful event that anyone can see even without a telescope—and that could spark interest in astronomy.

RND/dpa