"Manhattanhenge", is an phenomenon that occurs when the sunset align perfectly with the east/west streets of Manhattan, in New York City, USA. The term was coined by native New Yorker and astrophysicist Neil deGrasse Tyson, who was inspired by a visit to Stonehenge, a prehistoric monument located in Wiltshire, England, as a teenager. Tyson compared the solstice rays at the center of Stonehenge circle to the sun perfectly setting between the city’s high-rises.

Sunsets and sunrises each align twice a year, on evenly spaced dates around the summer solstice and winter solstice. The sunset alignments occur around May 28 and July 13. Sunrise alignments occur around December 5 and January 8.

The first ingredient has to do with its streets, according to plans developed in the early 19th century, they are built on a generally perpendicular grid, not directly east-west, but at an angle of 29° clockwise. clock from the east-west line. The other ingredient has to do with the fact that the Earth is not perfectly aligned with the sun: it has an axial tilt of approximately 23 degrees.

So as the direction of sunrise and sunset changes its alignment, it matches the alignment of the streets of Manhattan. Twice for sunrise and twice for sunset, the solar alignment matches the street grid.

Tyson suggests choosing one of the wider cross streets to view it, including 14th, 23rd, 34th, 42nd, and 57th streets.

More Info: en.wikipedia.org