By Lisbeth Levine
In late September we’ll experience a rare trifecta of night-sky alignments: a supermoon, a total lunar eclipse and a harvest moon—all on the same night.
At 10:50 p.m. EDT on September 27 in North America (September 28 at 2:50 UTC for those who want to calculate its arrival in other parts of the world), the night skies will be aglow with the biggest, brightest, boldest moon of the year. Correction: It would be the brightest moon of the year if it weren’t for the total lunar eclipse occurring the same evening. As if those two phenomena weren’t enough of a coincidence, this oversized orb also lays claim to being a harvest moon.
Because that’s a lot of celestial matter to digest, we’ve broken it down for you:
What is a supermoon? The moon orbits Earth in an elliptical pattern, so its distance from our planet varies. When a full moon occurs and the moon is at or near its closest point in the orbit, the moon appears larger and brighter. In recent years this has become known as a “supermoon.” The technical term is a “perigee full moon” and it’s about 31,069 miles (50,000 km) closer than its opposite, an apogee moon. The supermoon of September 27 will be the closest of the year, at 221,753 miles (356,877 kilometers) from Earth.
How often do they occur? Definitions of supermoons vary, but according to astrologer Richard Nolle (he coined the term more than three decades ago), in 2015 there are three full supermoons, in August, September and October. Miss these and your next chance to see a supermoon is in October 2016.
What is a lunar eclipse? When the moon passes within Earth’s shadow, our view of it is obscured. This particular total eclipse—the fourth and last in a series—is also known as a blood moon due to the reddish cast it takes on from the brightness of the full moon.
When is the eclipse? The total eclipse will happen in the Americas from 10:11 p.m.–11:23 p.m. EDT on September 27 (2:11–3:23 UTC on September 28). You should be able to view a partial eclipse for an hour before and after. The eclipse is expected to be visible in the Americas, Europe, the Eastern Pacific, Africa and western Asia.
What is a harvest moon? The moon that falls closest to the autumnal equinox is known in the Northern Hemisphere as the harvest moon. What makes it a harvest moon isn’t an orange glow, but rather the fact that it rises earlier in the evening than usual, casting a bright light that helps farmers continue harvesting their crops past sundown.
One way to celebrate: In China and a number of other Asian countries, September 26 and 27 represent the Mid-Autumn Festival, during which people traditionally made sacrifices to the moon. Today it’s often celebrated by eating mooncakes and presenting them to family and friends.
Romancing the Moon: From Supermoon to Harvest Moon, Everything You Need to Know
By Lisbeth Levine