Thousands of people have been stopping in the middle of New York's busy streets and pointing their phones and cameras west, as a rare solar alignment takes place.
Once a year, the sun sets perfectly in line with Manhattan's famous grid-planned streets - a phenomenon now known as 'Manhattanhenge.'
For New Yorkers, it's probably the only time the city's air pollution has its benefits. The dirty red atmosphere creates a golden glow as the sun goes down.
When the city was designed, urban planners tilted the main streets of New York by 29 degrees, to roughly align them with the island's shape.
So, twice a year, when the sun goes down 29 degrees north of due west, 'Manhattanhenge' occurs.