Henge: A type of Neolithic earthwork featuring a circular banked enclosure with an internal ditch. The most famous henge is Stonehenge, in Wiltshire, England; it is estimated to have been built between 3000 and 2000 BCE. The -henge element “may have meant something ‘hanging’ or supported in the air,” according to the OED.
Detached henge first appeared in the mid-18th century; Daniel Defoe, author of Robinson Crusoe, wrote in his 1742 Tour of Great Britain that “The present Name [sc. Stonehenge] is Saxon, tho' the Work is beyond all Comparison older, signifying a hanging Rod or Pole, i.e. a Gallows, from the hanging Parts, Architraves, or rather Imposts; and pendulous Rocks are still in Yorkshire called Henges.”
Henge is in the news this week because of Manhattanhenge, an affectionate name for an annual east-west alignment of the setting sun with New York City’s street grid. The phenomenon occurs today, May 31, at about 8:12 p.m. (It also occurred on May 30, and will be visible again on July 11 and 12.)
According to a Wikipedia entry:
In accordance with the Commissioners' Plan of 1811, the street grid for most of Manhattan is rotated 29° clockwise from true east-west. Thus, when the azimuth for sunset is 299° (i.e., 29° northward of due West), the sunset aligns with the streets on that grid.
Other cities with fairly uniform grids and unobstructed views of the horizon may also experience the event. A similar phenomenon, dubbed MIThenge, can be experienced at varying times of the year.
Manhattanhenge observed from 34th Street. Photo via American Museum of Natural History.