The full moon of November 14 is not only the closest full moon of 2016 but also the closest full moon to date in the 21st century. Not since January 26, 1948 have we seen a supermoon this bright. The full moon won’t come this close to Earth again until November 25, 2034.
Originally a term from modern astrology for a new or full moon that occurs when the moon is within 90% of its closest approach to Earth in a given orbit, “supermoon” now refers more broadly to a full moon that is closer to Earth than average.
Why is the moon closer to the earth sometimes but not others?
Because the orbit of the moon is elliptical. Since the moon’s orbit is elliptical, one side (perigee) is about 30,000 miles (50,000 km) closer to Earth than the other (apogee). The word syzygy, (my favorite Scrabble word), is the scientific name for when the Earth, sun, and moon line up as the moon orbits Earth. When perigee-syzygy of the Earth-moon-sun system occurs and the moon is on the opposite side of the Earth from the sun, we get a perigee moon or more commonly, a supermoon!
This coincidence happens three times in 2016. On October 16 and December 14, the moon becomes full on the same day as perigee. On November 14, it becomes a full Taurus moon within about two hours of perigee—arguably making it an extra-super moon. But in the northern hemisphere Sunday, November 13 seems brightest.
It will rise in the east around sunset, climbs highest up around midnight, and then sets in the west at or near sunrise. So good views all night long!
Of course the effect of this closeness to earth is that the brightness and clarity of the moon is pronounced. A full moon on steroids. The moon can appear 14% bigger and 30% brighter than normal.
For more on beautiful views in the night’s sky, stay tuned to science.nasa.gov.