If you needed a reason to step outside, look up, and feel small in the Universe, next week gives an opportunity as good as any.
A moon becomes a “supermoon” when it appears up to 14 percent bigger and 30 percent brighter than when it’s at its farthest point in orbit, according to NASA. But not all supermoons are created equal: On Monday, Nov. 14, the moon will make its closest pass to Earth since 1948. The moon’s perigee, or nearest orbital approach to Earth, occurs at around 6 a.m. eastern time that morning. Dragging yourself out of bed pre-dawn is the best bet for East Coast viewing, but it’ll also be big and brilliant the night before, assuming skies are clear.
The phenomenon isn’t particularly rare — it’s just another word for a perigee full moon, and we’ve got them in October, November and December of 2016 — but this one’s exceptional, as it’s the closest pass in nearly 70 years. The next time it gets this close will be November 2034.
Although humans haven’t set foot on its surface in 44 years, NASA hasn’t forgotten about our constant companion. There’s a spacecraft orbiting it now: the Lunar Reconnaissance Orbiter. It’s been circling the moon since 2009, sending back data like temperature maps, a global geodetic grid, high-resolution color imaging and identifying sites for future landings, machine or human.
“I like to think of the Moon as another continent of the Earth,” NASA scientist Dr. Noah Petro wrote in an email. “Though separated from the Earth by space (and not an ocean), we can learn a lot about the environment at the early Earth by studying the Moon.”
Depending on which scientists you ask, the best reasons to look closely at the moon vary widely, Petro says. “My thought on this is that the Moon is an excellent place to study how processes influence planetary surfaces, like impact cratering, volcanism, interactions with the space environment.” They then apply this knowledge to other celestial bodies: For example, when Juno flew by Pluto and saw smooth surfaces, scientists knew those parts of the dwarf planet must be “young”, or recently resurfaced by geological activity, because of the aged terrain we’ve observed on the moon.
Recent research suggests that the moon’s formation was more like a blender-mix with Earth’s materials than previously thought, making its study that much more interesting. Studying how objects hit the moon gives us clues into Earth’s early days, too. “All of those impact craters on the Moon, the same types and sizes of objects were striking the Earth too,” Petro says. “So when we look at old surfaces and impact craters on the Moon, we can learn about the sizes of objects that were striking the Earth as well.”
Although it won’t change animal behaviors, the supermoon could bring slightly higher tides and seem a little brighter than usual, Petro says. “I also expect a number of humans waking up on Monday or Tuesday with a stiff neck after spending some time the night before looking up at the beautiful Moon!”
The last time the moon was this close to Earth, this happened:
Maybe in 18 years, when it swings back to meet the Earth this close again, we’ll be having a better year than the one that’s winding down now.