What is New York's famous Manhattanhenge?

Four times per year, thousands of New Yorkers and fascinated tourists flock to Manhattan’s streets for a glimpse of the spectacular celestial sunset known as Manhattanhenge.

Occurring twice in May and twice in July, the unique phenomenon features a perfectly aligned sunset beaming down the east- and westward roads of the borough’s grid.

The event can be seen when the sun is either partially or fully visible above Manhattan’s skyline.

The result is a dazzling glow that illuminates the north and south sides of the streets’ towering buildings.

Jacqueline Faherty, senior scientist at the American Museum of Natural History, called Manhattanhenge and similar events “delightful by-products of gridded cities.”

“In all, if you have a city built with east-west facing streets in 90-degree angles with the avenues, you can have such an event,” Faherty said.

“The beauty of it will depend on the horizon and the buildings that frame your view,” she added.

Visibility also depends on possible clouds ruining the display, which can happen in a matter of minutes, according to AccuWeather Chief Meteorologist Elliot Abrams.

If unfavorable weather conditions are kept at bay, hopeful spectators are treated to a breathtaking, picturesque view of the Manhattan sunset.

It’s no coincidence that Manhattanhenge sounds a lot like another world-famous “-henge.”

Stonehenge, Europe’s best-known prehistoric monument, inspired the name coined by astrophysicist Neil deGrasse Tyson in 2002.

That such a striking urban phenomenon exists is completely unintentional, however.

“The city planners of Manhattan certainly didn't expect for this to happen,” said Faherty.

Both Manhattanhenge occurrences happen to coincide with Memorial Day and Major League Baseball’s (MLB) All-Star Game.

Because of this, deGrasse Tyson wrote on his blog, “Future anthropologists might conclude that, via the sun, the people who called themselves Americans worshiped war and baseball.”

Part of what makes Manhattan such a great “-henge” location is its relatively low skyline, which gives it a somewhat flat horizon as seen from the borough’s streets, Faherty said.

“On top of that, Manhattan has iconic buildings that many people around the world can recognize,” Faherty said. “Those buildings frame the sun perfectly for an epic photograph.”

According to deGrasse Tyson, Manhattanhenge would have coincided with the spring and fall equinoxes if the borough’s grid were aligned perfectly with the geographic north-south line.

“But Manhattan's street grid is rotated 30 degrees east from geographic north, shifting the days of alignment elsewhere into the calendar,” he wrote.

For the best Manhattanhenge experience, deGrasse Tyson wrote that observers should find the easternmost point in Manhattan as possible, ensuring that New Jersey is still visible when looking west across the avenues.

DeGrasse Tyson also suggested cross streets including 14th, 23rd, 34th, 42ndand 57th streets as prime sunset-viewing spots.

“Manhattanhenge times [occur] in an ideal part of the year: summer, when the sun sets late, the outside temperatures are warm and comfortable and people are in generally good moods,” Faherty said.

Though Manhattanhenge seems to be the most talked about, other “-henge” events also occur in other cities with uniform street grids, including Torontohenge, Bostonhenge and Chicagohenge.

Those who can’t make it to New York City for the popular event can still spot amazing “mini-henges” throughout the year.

Online mapmaking company Carto created a map called NYCHenge, which displays optimal sunset days and New York City locations year-round.