It's a semi-annual alignment of sun and skyscrapers in downtown New York and it's happening tonight at 8:12 p.m. ET.
Tonight, the "full sun" Manhattanhenge will be visible, weather permitting.
According to the American Museum of Natural History: "For best effect, position yourself as far east in Manhattan as possible. But ensure that when you look west across the avenues you can still see New Jersey. Clear cross streets include 14th, 23rd, 34th. 42nd, 57th, and several streets adjacent to them. The Empire State building and the Chrysler building render 34th street and 42nd streets especially striking vistas."
Never heard of Manhattanhenge?
It is a concept popularized by astronomer Neil deGrasse Tyson, a native of New York City, who says he was inspired by research he did in his youth in the British Isles, where he studied stone monuments that are "less celebrated and less grand and less preserved" than the famous Druid temple Stonehenge, believed to date from about 3000 B.C.
"I thought in an apocalyptic Earth, if there's nothing that survives but our street grid, what would they say of us? Surely, future anthropologists would argue that we arranged our grid to align with the sun on purpose on those days," Tyson says, who is director of the Hayden Planetarium in New York.
He started promoting Manhattanhenge about 15 years ago. Today, it attracts thousands of people into the streets to witness the phenomenon.
Accuweather is forecasting "some clouds" tonight, but enthusiasts are already getting their cameras ready. Even so, there's another chance this year — on July 12 and 13.