NEW YORK (AP) — Wednesday and Thursday are the last two days of Manhattanhenge, the biannual alignment of the setting sun with the city's east-west streets that brings New Yorkers out of their apartments to watch it bathe the urban canyons in a rosy glow.

With forecasters predicting gloomy weather, fans of the spectacle will have to hope the clouds part at the right time.

“We have had luck in the past when the weather clears,” said Jackie Faherty, an astrophysicist at the American Museum of Natural History whose sold-out lecture on Manhattanhenge on Thursday will be followed by a viewing party. “All we need is for it to be clear at sunset.”

It was Neil deGrasse Tyson, director of the museum's Hayden Planetarium, who coined the term Manhattanhenge to describe the phenomenon. He was inspired by Stonehenge, where tourists and modern-day Druids camp out on the summer solstice to watch the rising sun align with the prehistoric stones.

Manhattanhenge attracts its own Druids when it happens for two nights around Memorial Day and another two in mid-July. Devotees line thoroughfares like 42nd and 34th streets to watch the sun's disc sink below the horizon, perfectly framed by the gleaming towers.

There are are also sunrise Manhattanhenge days in December and January, but those have not drawn crowds for reasons including the hour and the chill, Faherty said.

Other cities where streets align with the sun on certain days include Boston and Toronto. The best-known urban “henge” other than New York's is Chicagohenge, which happens during the spring and fall equinox.

Faherty said she prefers Manhattanhenge because New York has more iconic skyscrapers and the Hudson River to the west provides “a visual break in the landscape of buildings.”

Weather permitting, fans will flood the streets and point their phones and cameras at the fading light.

“In this era of social media, it’s a gorgeous picture,” Faherty said. “I often call it the Instagram holiday for New York City.”