On Sunday night, the most notable object in the sky will not be a bird or a plane, but the 2017 supermoon.
A supermoon occurs when the moon reaches its perigee at the same time it is in the full moon phase, said Angela Speck, director of astronomy and professor of astrophysics at the University of Missouri. This makes the moon appear 14 percent larger and 30 percent brighter than usual.
The perigee is the point in a moon’s orbit when it is closest to the Earth’s surface — about 222,000 miles away, according to space.com. The moon’s elliptical orbit causes its distance from the Earth to vary by 30,000 miles.
The full moon will rise around 4 p.m. Sunday and reach its perigee at 4:45 a.m. Monday.
The best time to view will be just after sunset on Sunday when an optical effect will cause the moon to appear bigger and brighter than when it is high in the sky, according to National Geographic.
Speck said both the full moon and perigee happen once each month, but because of the Earth’s orbit around the sun, they don’t always coincide.
The supermoon phenomenon will happen only once this year, but last year it occurred three months in a row, October, November and December. In 2016, the moon was the closest it had been to Earth since 1948.
Next year, there will be two January supermoons, one beginning on Jan. 1 and the second on Jan. 31.