Full moon happens at the same instant worldwide on December 3, 2017 at 15:47 UTC; translate UTC to your time zone. It’ll be 2017’s first, last and only supermoon. In other words, this full moon will be near perigee, or the closest point of the moon in orbit for this month. Your eye probably can’t detect a difference in size between the December 3 supermoon and any ordinary full moon (although experienced observers say they can detect a size difference). But the supermoon is substantially brighter than an ordinary full moon.
Like every full moon, this one is opposite the sun from Earth. It’ll rise in the east as the sun sets in the west, ascend to its highest point in the sky in the middle of the night, and set in the west around dawn. Clouded out on December 3? The Virtual Telescope Project in Rome is offering an online viewing of the supermoon.
The December 2017 supermoon will be the first of three full moon supermoons in succession. The two full moons in January 2018 – on January 2 and 31 – also count as supermoons.
Some people will call the full moon on January 31 a Blue Moon because it’ll be the second of two full moons in one calendar month.
Moreover, the January 31, 2018 supermoon will stage a total eclipse of the moon: a super Blue Moon eclipse!
As the moon orbits Earth, it changes phase in an orderly way. Follow these links to understand the various phases of the moon.
Where’s the moon? Waxing crescent
Where’s the moon? First quarter
Where’s the moon? Waxing gibbous
What’s special about a full moon?
Where’s the moon? Waning gibbous
Where’s the moon? Last quarter
Where’s the moon? Waning crescent
Where’s the moon? New phase
Bottom line: A full moon looks full because it’s opposite Earth from the sun, showing us its fully lighted hemisphere or day side. The December 3, 2017 full moon is a supermoon.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.