This weekend's is the first supermoon in just about a year.

The supermoon from November 2016
A Supermoon rises against the skyline in Madrid on November 14, 2016. The phenomenon happens when the moon is full at the same time as, or very near, perigee -- its closest point to Earth on an elliptical, monthly orbit. It was the closest to Earth since 1948 at a distance of 356,509 kilometres (221,524 miles), creating what NASA described as 'an extra-supermoon'.
| Credit: GERARD JULIEN/Getty Images

The first visible supermoon in just about a year takes place this weekend, giving stargazers a rare glimpse to view the moon at its biggest and brightest. But what exactly is a supermoon, and if it's so special, when will it happen again next?

A supermoon is a full moon, but a full moon is not necessarily a supermoon. In fact, it usually isn’t. A supermoon only occurs when a full moon coincidentally falls during the period when the moon is the closest distance from Earth during its orbit. This makes the full moon appear even larger and luminous due to its increased proximity to the planet.

It’s worth noting that a supermoon technically occurs during a new moon, too, but that phenomenon usually isn’t referred to as a supermoon since new moons are not visible in the night sky.

When is this weekend’s supermoon?

When was the last supermoon?

The last supermoon occurred approximately a year ago on December 14. But the supermoon that took place exactly a month before that was much more notable — it was the closest supermoon to Earth since January 1948.

When is the next supermoon?

If you aren’t able to observe this weekend’s supermoon, don’t worry: The new year kicks off with two supermoons straight from the gate. The celestial events will be visible on both January 2 and January 31, but those conclude the remainder of 2018’s supermoons, so make them count.

If you want to witness a peak supermoon at maximum size and brightness like the aforementioned 1948 supermoon, it’s going to be awhile. The next time the moon will come that close to the Earth will be on November 25, 2034. But that doesn't mean this weekend's supermoon won't be beautiful — expect a full moon at least 7 percent bigger and 16 percent brighter than usual.