What is a 'Supermoon?' August's Will Be The First Of Three In A Row

If you’re out Saturday night, and it’s a clear night, take a second to look up.

August 29 will be the first “Supermoon” of three in a row this fall. Swampscott’s forecast for Saturday night is calling for partly cloudy skies, so it looks like you’ll have at least a decent chance of catching a glimpse.

What is a Supermoon?

Supermoon is the unofficial term for when the full moon cycle coincides with the moon’s closest approach to Earth during its oval-shaped orbit. The moon appears slightly larger than normal in the sky and can make for a spectacular view.

The technical term is full moon perigee. Perigee is when the moon is closest to the Earth, as opposed to apogee, which is when it’s the farthest.

The image above shows the relative sizes of the moon during both.

The term Supermoon was first used in 1979 by astronomer Richard Nolle, who defined it as a full moon that occurs within at least 90 percent of its closest orbit, according to space.com.

Sept. 28 and Oct. 27 will also fall under this definition, with September’s full moon being the largest of the three, as well as a total lunar eclipse, or “blood moon,” according to EarthSky.

Image via NASA on YouTube