Tomorrow is the spring equinox. I still remember the evening walk when Dad pointed out to me how the sun sets on the equinox (when the sun “passes over” the equator and days and nights are equal length.) The streets of our hometown were laid out in a North-South, East-West grid. So, every spring and fall equinox the sun would set down the middle of our westbound streets.
The island city of Manhattan, however, has a slanted street grid. The westbound streets point northwest to 299°, rather than to a true East of 270°. This means that they experience this sunset phenomena on different dates: May 28-30 and July 11-13 (before and after the summer solstice in late June.) These days make for rather good urban photographs. In 2002, astrophysicist Neil deGrasse Tyson popularized a name for this local New York phenomena: Manhattanhenge.