Don’t Miss The Supermoon This Sunday, If Your Local Weather Doesn’t Let You Down
The term “supermoon” is popular vernacular. Its scientific name is perigee syzygy. University of Arizona professor Gurtina Besla says the phrase means two specific things in reference to the moon’s placement and phase. This year’s December event will fall on the afternoon/evening of December 3, 2017.
According to NASA, it’s used by the media today to describe what astronomers would call a perigean full moon: a full moon occurring near or at the time when the moon is at its closest point in its orbit around Earth.
A supermoon can appear as much as 14% bigger and 30% brighter than when a full moon is at its farthest distance from Earth, NASA said.
It will be at its brightest at 4:47PM and will shine like a flashlight as it reaches the center of the night sky. It won’t actually reach perigee – or the point at which it’s closest to Earth – until the next morning. But again it will be very close for the entire evening, so you’ll get a look at it whenever you look up to the sky.
The moon is usually about 238,000 miles away from Earth. But its orbit isn’t a perfect circle, so it sometimes gets much closer, and when it swings around in December it will be a mere 222,135 miles away.
If you miss this one, however, don’t fret: The first two full moons of 2018 will be supermoons. Bigger and brighter than a typical full moon, the term “supermoon” was coined in 1979 by astrologer Richard Nolle. It’s now in regular use along with the terms “full moon” and “cold moon”.
Full moons occur when the Earth is directly in line between the moon and the sun. Appearing every 29 and half days, they take place when the Moon is completely illuminated by the Sun’s rays. A cold moon is also called Long Nights Moon, and the Moon before Yule. It refers to a full moon in December when winter would typically tighten its grip, bringing shorter days and longer nights.