BIGGEST FULL MOON OF THE YEAR
If you think tonight's Moon looks unusually big, you're right. It's the biggest full Moon of 2010. Astronomers call it a "perigee Moon," some 14% wider and 30% brighter than lesser full Moons of the year. It is also referred to as a Wolf Moon.
Johannes Kepler explained the phenomenon 400 years ago. The Moon's orbit around Earth is not a circle but an ellipse, with one side 50,000 km closer to Earth than the other. Astronomers call the point of closest approach "perigee," and that is where the Moon will be Friday night through Saturday morning. In a celestial coincidence, Mars is also very close to Earth as well, visible just to the left of the moon in the second image below.
January 29, 2010