The Moon's remarkable luminosity sprung from its proximity--about 50,000 km closer to Earth than other full Moons of the year. This can happen because the Moon's orbit is not a circle but an ellipse: diagram. Last night, the Moon was on the near side of the ellipse--a place astronomers call "perigee"--making it a big, bright perigee Moon.
The "Wolf Moon" designation applied to January full moons comes from Native American tradition, according to the Farmers' Almanac. If you missed last night's maximum, it will still be impressive tonight. Those experiencing cloudy weather can watch the movie "Moonstruck" instead.
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