Manhattanhenge is a phenomenon in which the setting sun aligns with the east-west streets of Manhattan. The phenomenon occurs twice yearly, before and after the summer solstice. This year there will also be two additional days in which the full sun will be seen just above the horizon (not quite a sunset but still spectacular). The first Manhattanhenge of 2012 is tonight at 8:17pm.
Additional 2012 Manhattanhenge events:
– Wednesday, May 30 at 8:16pm (full sun)
– Wednesday, July 11 at 8:24pm (full sun)
– Thursday, July 12 at 8:25pm
Astrophysicist Neil deGrasse Tyson explains Manhattanhenge in detail (including how best to view it) in this article for the Hayden Planetarium.