Twice per year, New Yorkers and visitors are treated to a phenomenon known as Manhattanhenge, when the setting sun aligns with the Manhattan street grid and sinks below the horizon framed in a canyon of skyscrapers. Twice per year, New Yorkers and visitors are treated to a phenomenon known as Manhattanhenge, when the setting sun aligns with the Manhattan street grid and sinks below the horizon framed in a canyon of skyscrapers. Space Exploration Phys.org – latest science and technology news stories