Supermoon to Light Up the Sky for the First Time in 2017

Moon soon to be open for business

Look to the rising moon Sunday night because it's going to be big - supermoon big.

The December full moon happens this weekend and it will be extra special this year because it's the only supermoon of 2017.

On Sunday, stargazers, astronomers and curious sky-watchers will get a chance to witness the first and only supermoon of 2017. (The point at which the moon is closest to Earth is known as the perigee.) Basically, what that means is it will look like the moon is particularly large and bright to viewers of the nightsky.

The best time for moon-watching will be just after sunset, when the moon is beginning to rise.

On Dec. 4, the high tide will reach 6.8 feet at 9:30 Port San Luis. The moon's orbit around Earth isn't a flawless circle, which means that its distance to Earth changes as it goes around.

However, on Sunday night, the moon will still shine 16% brighter and appear 7% larger than its usual size. The moon will still be super-sized when it becomes visible that evening and will officially reach its perigee at 3:45 a.m. ET on December 4.

If you miss this one, however, don't fret: The first two full moons of 2018 will be supermoons.

The next time a full moon will appear that close: November 25, 2034.

A supermoon occurs when the sun, moon and Earth align, and a full or new moon aligns with the sun's lunar orb.

We have a full moon about every 28 days, but the average for a supermoon is about every 14th full moon.

The distance between the moon and Earth constantly changes. If you choose to watch it live, check what local time you should tune in here. This is because the previous two were around the time of a new moon, which isn't visible in the sky.

According to, supermoons will look about 7 percent bigger than an average full moon (and 12 to 14 percent bigger than a full moon at apogee).