Mark your calendars.
Fall 2016 is proving to be an exciting season for stargazers, with three consecutive supermoons (which happen when the moon is closest to Earth) occurring in October, November, and December. But the upcoming supermoon on Monday, Nov. 14 will be particularly special, due to a unique alignment of the Earth, moon, and sun. The moon will be the closest it's been to the Earth since January 26, 1948—the next similarly large supermoon won’t occur until November 25, 2034. In short: You won't want to miss it.
On the night of the supermoon, the diameter of the moon could appear up to 14 percent larger and the total area of the moon may look up to 30 percent larger and brighter, according to Jonathan Kemp, a telescope specialist at Middlebury College Observatory. The moon appears so large due to its positioning on its orbit.
“The moon’s orbit is not a circle, but rather an ellipse, just as with the planets,” Kemp says. “On average, the moon is about 239,000 miles away from the Earth. When it is at perigee, or its closest point to Earth, it can be about 225,000 miles away. When this happens during full moon, the apparent size of the moon, as seen from Earth, appears to increase.”
This month, the full moon will occur within about two hours of the moon’s perigee, causing the extra-special supermoon. And because there is typically one supermoon per year, the fact that there are three in three months is also pretty spectacular.
The best way to view the supermoon is look for it low in the sky (as it rises or sets near the horizon) with foreground reference points (like buildings) to provide some context, Kemp says. Because it’s a full moon, it will rise as the sun sets, and set as the sun rises. With binoculars, you’ll get an even more exciting sight.
“When the moon is full, the larger craters show ‘ray’ features, which look like lines pointing away from the crater, spanning much of the surface of the moon,” says Jason Kendall, who is on the board of the Amateur Astronomers Association of New York. "These 'rays' are streams of rock that were ejected when the crater was formed by a colliding asteroid long, long ago.”