2024-08-20 06:55:34
In the evening, a celestial phenomenon occurs: a so-called blue moon. Even though experts have differing opinions, today’s moon is special.
Tonight the night sky will shine brightly because a special celestial event is about to take place. Firstly, the moon is particularly close to the earth and therefore appears larger than usual. “Today’s full moon will take place at a distance of 361,969 kilometers,” said Björn Voss, director of the Hamburg Planetarium, in an interview with t-online.
Normally, the distance of the moon from the earth varies between 406,000 and 356,000 kilometers. That is why today’s full moon is referred to as a so-called supermoon. “A supermoon appears about seven percent larger and 15 percent brighter than an average full moon.” But according to Voss, the full moons in September and October are much closer to the earth and therefore appear even larger.
On the other hand, today’s full moon is part of another celestial event known as a seasonal blue moon. In English, the saying “once in a blue moon” refers to a rare event. But how rare is a blue moon? And what exactly is it?
The definition is not entirely clear. Astronomy refers to the second full moon of the month as a blue moon. Since there are approximately 29.5 days between two full moons, according to the US space agency NASA, a second full moon occurs on average every 2.5 years in a month with 30 or 31 days – February, on the other hand, can never have a blue moon. This definition is now generally accepted.
But there is another interpretation that hardly anyone knows about. The Austrian astronomer Florian Freistetter traces the name of the blue moon back to the agricultural calendar from the 19th century. There, full moons were divided according to the seasons, Freistetter writes on the science portal “spektrum.de”.
While three full moons normally appear in the sky during the four seasons, in some years four full moons can be seen in one season. The third of four of these full moons is then called a “Blue Moon”.
Even if there is no uniform definition, one thing is certain: the “Blue Moon” is not blue. Where the name comes from is not entirely clear. According to NASA, the name can be traced back to a volcanic eruption in Indonesia. In 1883, the volcano Krakatoa spewed so much dust into the atmosphere that the moon actually appeared blue.
According to Voss from the Hamburg Planetarium, the English saying “Once in a Blue Moon” is behind the name. This is intended to indicate the rarity of this event. The moon itself, however, is the same color as usual.
According to the agricultural calendar, the actual blue moon can be seen in the night sky tonight. According to astronomer Freistetter, however, it doesn’t matter which definition you follow. “From an astronomical point of view, the moon is doing what it has always done.” After all, it’s not his fault that our calendar is so poorly organized.