Author: Michael J. I. Brown, Associate Professor in Astronomy, Monash University

A supermoon may sound exciting, but it’s a modest coincidence. As the Moon orbits Earth, its distance from us varies from 357,000 to 407,000 kilometres. When the Moon and the Sun are in almost opposite directions from Earth, we get a full moon. A “supermoon” is a full moon where its position along its orbit is within 10% of its closest approach to Earth. That’s it. This means a supermoon has an apparent diameter that’s 14% larger than the smallest possible full moon. That’s not a lot. You can’t really notice the difference by eye. As an astronomer, I have…