Interesting in the mysteries of space? Well, there’s a galactic double feature far, far better than Barbenheimer out this August: two supermoons that won’t be seen again until January of 2037, so now’s the time to break out the binoculars or telescope and aim at the moon.
The first, visible from August 1st through August 3rd, is a “sturgeon supermoon.” It rose on August 1 and it will set on August 3. The second, visible on August 30th, is a rare, super blue moon. The moon at both of those dates is called a “supermoon” because this is the time of month that the moon reaches its “pedigree,” or closest point to Earth in its elliptical orbit around our planet.
In-the-Sky, noting why that pedigree is interesting to skywatchers, notes, “Although the angular size of the Moon only changes by a very modest amount in reality, a very common optical illusion is that the Moon appears very much larger than it really is when it is close to the horizon. This is called the Moon illusion – and is nothing more than an optical illusion. Any photograph will reveal that the Moon is exactly the same size regardless of whether it appears on the horizon or directly overhead. The reason why we perceive this optical illusion is hotly debated. However, it may explain why some people are convinced that the Moon appears larger on some nights than others, despite the actual changes in its true size being so small.”
So, a glance toward the heavens turns into shock if you’re not expecting it, as the moon appears to be so much larger than it normally is. But the supermoon aspect of this month’s moon double feature is just half of what makes each one so interesting.
The supermoon from August 1-3 is called the “Sturgeon” supermoon because, according to the Old Farmer’s Almanac, the August full moon is traditionally known as the “sturgeon moon” because of the abundance of that fish in the Great Lakes in August hundreds of years ago.
The rare, super blue moon is called such because not only is it a “supermoon” but because two full moons fall on the same month, which is what “blue moon” means. Though blue moons are relatively frequent, occurring every few years, the concurrence of a “super moon” and “blue moon” is relatively rare, with the two supermoons not occurring again until January 2037.
In-the-Sky, describing what a blue moon is and from where the term originated, said, “This will be the second full moon of August 2023, making it a blue moon – a term used to describe any full moon which is the second to fall within a single month. This use of the term first appeared in the March 1946 issue of Sky & Telescope magazine, where it was incorrectly stated that this was an established tradition. In fact, it was an entirely new usage of the term, although it had previously been used by the Farmers’ Almanac with a different definition. However, the Sky & Telescope article became widely cited, and the term has now entered common usage. It is possible for two full moons to fall within the same calendar month since the Moon’s phases cycle, on average, 12.37 times each year. As a result, once every 2.8 years, a single year contains 13 full moons rather than the usual 12, and in that a year, one of the months must have two full moons.”
Featured image credit: By Crefollet – Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=60664454
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