Tonight is the full cold moon — the name of the December full moon — but this full cold moon is special: That’s because tonight, December 13, is also a Supermoon — good for the third such “supermoon” of 2016.
The moon will be at its peak at 7:05 p.m. Eastern time on Tuesday evening, so don’t worry about staying up late. Because the peak is pretty close to moonrise (around 4:40 p.m. Eastern), the Moon should be lower in the sky, creating a bit more of a “moon effect” where the Moon appears larger closer to the horizon. The Moon will be in the sky until around dawn, though, so don’t plan on waiting it out to catch the peak of the Geminids meteor shower.
Supermoons appear to be as much as 15 percent larger in the sky, and as much as 30 percent brighter. The natural phenomenon occurs when the perigee (closest approach by the Moon to Earth) coincides with it being full (completely illuminated by the Sun).
December’s supermoon won’t be quite as big as November’s, because the November supermoon was the closest the moon will get to Earth until 2034. But tides will still be high, and the sky will still be bright. We got lucky with three supermoons this year, because the Moon’s closest point to Earth also happened to be the point when it’s opposite the Sun.
If cold and clouds keep you from seeing the last supermoon until May 2017, you can always live-stream the event over on Virtual Telescope.