Nov. 14, 2016
Right before sunrise on Monday, something really super is going to happen. That’s when we’ll be treated to a “super, supermoon” – a full moon at its closest distance to Earth - but one that’s even more spectacular than usual, says Matt Benjamin with CU Boulder Fiske Planetarium, because this is the closest the moon has been to Earth since 1948.
“Yes, this is the super, super moon I guess would be the way to say it. This is going to be a very fun, large astronomical event. This is one of those that you will be able to notice. When you get a full moon that happens to align perfectly with it being at perigee – at its closes point – you tend to see brilliant effects, which is the moon being 30 percent brighter or appearing 14 percent bigger. You will notice it.”
NASA says the moon will be closest at 4:21 a.m., MST, when it comes within 221,523 miles of Earth. But even though it’s not full until Monday morning, Benjamin says the moon will still be worth seeing Sunday evening when it rises.
“Right at sunset look to the east and you’ll see the moon rise. This is when most people take those beautiful pictures of a big moon with trees or a building or cars. When it’s on the horizon it appears even larger than it does on the sky.”
The reason we have a supermoon, says Benjamin, is that the moon’s orbit is not perfect.
“Everything that orbits in our solar system orbits in what we call an ellipse. There are no perfect circles of orbits. And when you have an ellipse there is a part of your orbit that is closer to the host object and a part of the orbit that is farther away. (:16) We have terms like perigee and apogee to refer to the near point of an orbit and the distant point of an orbit. So for the sake of the moon - we’re interested in the perigee - when the moon’s orbit is closest to Earth.”
According to NASA, the last time the moon was this close - actually, 29 miles closer - was in January 1948. In 2034, the moon will come even closer, coming within 221,485 miles.