Two evenings this week New Yorkers will hope for clear skies to observe Manhattanhenge, a chance to stand side by side and watch the sunset reflect off towers of glass and steel.

The big-city camaraderie occurs for two evenings twice a year  in late May and again in mid-July. The first pair of evenings this year is May 28 and 29.

Neil deGrasse Tyson, planetarium director at New York’s American Museum of Natural History, named the phenomenon Manhattanhenge with a nod to England’s ancient stone enigma in the belief that some future civilization will imagine Manhattan’s perfect grid layout must have held astrological significance. While the sunrise aligns with Stonehenge on the summer solstice each year, the dates of Manhattanhenge coincide roughly  with the U.S. Memorial Day and Major League Baseball’s All-Star break.

Similar events occur in other U.S. cities, including Boston and Chicago, at different times of the year.