If Manhattan's streets were perfectly laid out on an east-west grid, Manhattanhenge would occur facing both east and west on the vernal and autumnal equinoxes.

BBC: Just what is Manhattanhenge?

Notably, every 18.6 years, during the northern lunar standstill, the moonrise is aligned with the sites two rock pinnacles, as well as during the summer and winter solstices, and the fall and spring equinoxes.

WHITEHOUSE: The White House

Although the seasonal equinoxes and solstices seem to divide the year into four equal parts, when you count the days of what we officially call winter, spring, summer and fall, each season is different, says Bing Quock, acting chairman of the Morrison Planetarium at the California Academy of Sciences.

NPR: Not All Seasons Are Created Equal