Last Sunday, the sun set in perfect alignment with the east-west streets of the primary sections of New York City's Manhattan street grid. Astrophysicist Neil deGrasse Tyson, the Director of the Hayden Planetarium of the American Museum of Natural History named the urban phenomenon MANHATTANHENGE, Manhattan's version of Stonehenge. The most common photographs of Manhattanhenge feature spectacular vistas including the Empire State Building (32nd Street) and the Chrysler Building (42nd Street). I made the images above on 57th Street on July 11. Manhattanhenge occurs several times a year.
From the Hayden Planetarium website:
Tyson, (who also tweets,) explains Manhattanhenge on his website: As you may know, had Manhattan’s grid been perfectly aligned with the geographic north-south line, then the days of Manhattanhenge would be the spring and autumn equinoxes, the only two days on the calendar when the Sun rises due-east and sets due-west. But Manhattan’s street grid is rotated 30 degrees east from geographic north, shifting the days of alignment elsewhere into the calendar.
Note that any city crossed by a rectangular grid can identify days where the setting Sun aligns with their streets. But a closer look at such cities around the world shows them to be less than ideal for this purpose. Beyond the grid you need a clear view to the horizon, as we have over New Jersey. And tall buildings that line the streets create a kind of brick and steel channel to frame the setting Sun, creating a striking photographic opportunity. What will future civilizations think of Manhattan Island when they dig it up and find a carefully laid out network of streets and avenues? Surely the grid would be presumed to have astronomical significance, just as we have found for the pre-historic circle of large vertical rocks known as Stonehenge, in the Salisbury Plain of England. For Stonehenge, the special day is the summer solstice, when the Sun rises in perfect alignment with several of the stones, signaling the change of season.
For Manhattan, a place where evening matters more than morning, that special day comes twice a year. For 2010 they fall on Sunday May 30th, and Monday July 12th, when the setting Sun aligns precisely with the Manhattan street grid, creating a radiant glow of light across Manhattan's brick and steel canyons, simultaneously illuminating both the north and south sides of every cross street of the borough's grid. A rare and beautiful sight. These two days happen to correspond with Memorial Day and Baseball's All Star break. Future anthropologists might conclude that, via the Sun, the people who called themselves Americans worshiped War and Baseball.
For these two days, as the Sun sets on the grid, half the disk sits above and half below the horizon. My personal preference for photographs. But the day after May 30th (Monday, May 31), and the day before July 12 (Sunday, July 11) also offer Manhattanhenge moments, but at sunset, you instead will find the entire ball of the Sun on the horizon.