A rare Halloween 蓝月亮 has been thrilling skywatchers across the globe.
As the second full moon of the month, it is classified as a blue moon. “In recent years, people have been using the name Blue moon for the second of two full moons in a single calendar month,” explains NASA, on its 网站. “An older definition of Blue moon is that it’s the third of four full moons in a single season.”
Skygazers, 然而, should not expect the Halloween blue moon to be, well … blue. “Most Blue Moons look pale gray and white, indistinguishable from any other Moon you’ve ever seen,” explains NASA.
In rare circumstances, 然而, the moon can look blue. “A truly-blue Moon usually requires a volcanic eruption,” explains NASA. “Back in 1883, 例如, people saw blue moons almost every night after the Indonesian volcano Krakatoa exploded with the force of a 100-megaton nuclear bomb. Plumes of ash rose to the very top of Earth’s atmosphere, and the Moon … it turned blue!”
Fox News’ Chris Ciaccia contributed to this article.
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