It’s an extremely rare occurrence. 

By Grace Elkus
Updated June 20, 2016
Jamie Yan/EyeEm/Getty Images

If today feels like it’s dragging on forever, it’s not just because you have a case of the Mondays. June 20, 2016, is the summer solstice in the Northern hemisphere, marking the official first day of summer—and the longest day of the year north of the Equator. From today onwards, the length of the days will begin to shorten.

Though the summer solstice occurs every year (with a winter solstice occurring in the Northern hemisphere in December), this year is unique because it falls on the same day as the Strawberry Moon, a full moon named by the Algonquin tribe to signify that the strawberries are at peak ripeness. This only happens every several decades.

“When it’s the month of June, and it’s a full moon, the strawberries are ripe for picking,” says Jason Kendall, who is on the board of the Amateur Astronomers Association of New York. “The Europeans call it the rose moon because that’s when the roses bloomed for Louis XIV.”

The exact moment of the solstice, which occurs when the Earth’s axis is maximally tilted towards the sun, is at 6:34 p.m. EST. When the sun sets, you can look for the full moon rising across the sky.

“A full moon is generally visible all night and, depending on your location, the full moon can rise around sunset and set around sunrise,” says Jonathan Kemp, a telescope specialist at Middlebury College Observatory. “The full moon should be plainly visible in the night sky, weather permitting in the late evening and early morning hours.”

The number of daylight hours you’ll experience will differ depending on the latitude of your location. In New York City, for example, the sun rose at 5:25 a.m., and will set at 8:30 p.m., making the day a total of 15 hours and 5 minutes.

“At a more southerly location like Hawaii, the length of the day will be a little longer than 13 hours,” Kemp says. “In Alaska, however, the length of the day continues to increase the further north you go. At any location north of the Arctic Circle, the sun simply stays up all day and night on the summer solstice.”

Calculate when the sun rises and sets in your city here.