The strange reason why tonight’s full moon is “blue”

Astrophysicist Gianluca Masi captured this photo of the May 2019 Blue Moon rising over a Roman cathedral. (Image copyright Gianluca Masi)

Typically, a Blue Moon marks the second full moon in the same month. But the full moon arriving on Saturday (May 18) is the first full moon in May. Why do people call it a blue moon? ” According to Life Science sister site Space, the answer has to do with a vague rule.

In this case, the May 18 moon (also known as the full moon) is called a blue moon, Because it is the third of four full moons in a season. According to space reports, there are usually only 3 full moons in each season. [Photos of the far side of the moon!]

Spring Equinox. begins on March 20. On that night, a pink full moon shines in the sky, on April 19. After the moon, the fourth and final full moon of the season, will light up the sky on June 17. Then, it will end on June 21, when the summer solstice arrives. The Obscure Blue Moon rule of "KdSPE" and "KDSPs" says that when there are four full moons in a season, the third one must be called a blue moon, so the fourth full moon can be called a "late moon," according to Space.

But despite its name, the moon is not tinted navy, aquamarine or bluish-purple. The moon appears blue only when the right atmospheric conditions occur on Earth. , a large volcanic eruption releases a large amount of dust, which will make the moon look blue to people on Earth, and so will dust storms and forest fires.

You can see the blue moon from Saturday. Beginning at 5:11 PM local time (2211 GMT), as long as the sky is clear. To watch it live over Rome, tune in here "KDSPE" Note to KDSPs editors: This post has been updated with changes. Summer Equinox to Summer Solstice. KDSPE Photos: Great American Solar Eclipse Photos of 2017: Great Shots from Wildlife Photographer of the Year Contest Photos: Ancient rock art depicts total solar eclipse in Chaco Canyon .

Originally published on Live Science.