Head outside at sunset tonight and look up at the sky. If the full moon seems a tad larger than normal to you, that means one of two things: You are exceptionally perceptive, or you were already expecting to be dazzled, after hearing some of the buzz about this year's "supermoon."
It turns out that all full moons are not created equal. That's because the moon's orbit around the Earth isn't a perfect circle — it's an ellipse. And tonight, we're in luck.