Topic analysis

Hengefinder: Finding when the sun aligns with your street

The article presents Hengefinder, a web tool developed at the Recurse Center that enables users to identify dates when the sun aligns with streets or canals worldwide, outlining technical challenges solved during its creation—including adjusting for Earth's curvature when calculating street bearings, using binary search to pinpoint the exact sunset alignment moment, and implementing a two-phase sampling method to find alignment dates efficiently. A mobile app extension by John Pribyl adds moon alignment and 'Sauron Henges' (sun/moon positioned atop buildings) functionality, and the piece highlights that unobserved solar alignment events occur regularly across the globe.