Today through Tuesday marks a biannual solar event called Manhattanhenge, where the rising or setting sun aligns with the east-west grid of Manhattan streets.


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Technically, "Manhattanhenge" occurs around the summer solstice, not on the solstice itself. That's because of the orientation of Manhattan's famous grid pattern — established by the the Commissioners' Plan of 1811 — is not perfectly aligned with the geographic north-south line; it's rotated 29 degrees east, shifting the dates of alignment.



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This kind of alignment is not unique to Manhattan; any city with a uniform street grid will have dates where the sun aligns with those streets, including Chicago, Toronto and Montreal.


Tyson has been outspoken in the past about astronomical inaccuracies in film and television. For instance, you can always spot a fake sunrise onscreen, because the sun will move up and to the left as it rises. In reality, the sun always rises up and to the right. Directors tend to film a sunset for such scenes and then just run it backwards to portray a sunrise, thinking nobody will notice. (And they'd probably get away with it, too, if it weren't for those meddling astrophysicists!)

The term Manhattanhenge technically applies to the setting sun phenomenon that flanks the summer solstice, usually around May 28 and July 12, although the precise dates vary slightly year to year. A similar alignment occurs with the rising sun around the winter solstice, usually Dec. 5 and Jan. 8.

Note: This is a re-published version of an article published on Discovery News in 2012.

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