First quarter moon falls at 21:20 UTC on April 27, 2023
Lunar X and Lunar V
Have you heard of Lunar X and Lunar V? They are famous optical features on the moon, visible through telescopes. So when the moon’s terminator – or line between light and dark on the moon – is located in just the right place, you can see a letter X and a letter V on the moon’s surface. A sign of an alien visitation? No. Lunar X is a great example of how lighting and topography can combine on a planet or moon to produce a pattern that seems familiar to the human eye.
In reality, the illusion of Lunar X is created by sunlight falling on the rims/ridges between the craters La Caille, Blanchini, and Purbach. The V is caused by light illuminating crater Ukert, along with several smaller craters.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. In 2020, she was the Education Prize from the American Astronomical Society, the largest organization of professional astronomers in North America. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.
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