Tonight’s full moon will be at its closest to the Earth since 1948, making it appear larger and brighter than usual.
The moon will appear around 14 percent bigger and 30 percent brighter compared with the smallest full moons. It will be worth taking a step outside to see this super supermoon.
What is a supermoon, and why does it happen?
The moon’s orbit around Earth is not a perfect circle. It’s an ellipse, a saucer shape that’s longer than it is wide. That means as the moon follows this orbit, it’s sometimes closer to the Earth and sometimes farther away. At perigee, the closest spot in its orbit to the Earth, it’s around 31,068 miles closer to Earth than at apogee, when it’s farthest away. [..]
But why is this supermoon extra special?
The moon will appear slightly larger than it has in decades because of mere chance. The moon will reach fullness just three hours after perigee on November 14. Because perigee and the full moon are so closely timed, this full moon will be the largest (relative to our perspective on Earth) since 1948. The next-closest supermoon will be in 2034, as NASA reports.
Again, though, the differences in size between a really close supermoon and a typical one would be are pretty negligible. The full moon Monday will be just 30 miles closer to Earth than the last record in 1948, National Geographic reports. In astronomical terms, that’s tiny.
The moon will also be a bit brighter than usual — also due to the fact that it will be a bit closer to the Earth.
As the Vox article notes, we are in a run of supermoons this year. If you miss this one, there is another December 14, albeit slightly smaller but hardly noticeable. After that, the nexxt one will be December 17, 2017.
Moonrise today on the eastern seaboard is at 4:16 PM ET, shortly before sunset, and sets at 5:06 AM ET. The moon won’t be actually full until 8:52 AM ET on Monday. So the moon will be as bright as tonight on Monday.