Social Media's Favourite Sunset: Manhattanhenge

This evening, the sun will line up perfectly with Manhattan’s grid, turning the city’s streets into glowing corridors of light.

This rare and radiant moment, called Manhattanhenge, provides picture perfect views straight to New Jersey and New Yorkers can catch it at around 8.20 p.m. The rest of us can catch it a few moments later on the social media feeds of friends, family and tourists in New York.

Manhattanhenge was named by astrophysicist and National Geographic Explorer Neil deGrasse Tyson, who was inspired by England's Stonehenge - one of the wonders of the world and the best-known prehistoric monument in Europe. As head of the American Museum of Natural History’s Hayden Planetarium, he began calculating the dates in the late 1990s. He coined the term in 2002, according to The New York Times.

The spectacle is possible thanks to Manhattan’s 19th-century street grid, which was designed with 90-degree angles. While many people assume the sun sets due west each evening, it actually only sets due west twice a year, on the spring and fall equinoxes. During the rest of the year, the sunset drifts slightly north across the horizon until the summer solstice and then heads south again. If New York’s grid had been oriented due north, says NatGeo, Manhattanhenge would coincide with the equinoxes. But because the grid is tilted about 30 degrees east from geographic north, it happens on different, “Manhattanhenge” days.

“Manhattanhenge is ‘astronomy in your face,’” says Jackie Faherty, an astrophysicist at the American Museum of Natural History, who now calculates the event’s dates.