Burt's solar compass or astronomical compass/sun compass is a surveying instrument that makes use of the Sun's direction instead of magnetism. William Austin Burt invented his solar compass in 1835. The solar compass works on the principle that the direction to the Sun at a specified time can be calculated if the position of the observer on the surface of the Earth is known, to a similar precision. The direction can be described in terms of the angle of the Sun relative to the axis of rotation of the planet.

The sunstone is a type of mineral attested in several 13th–14th-century written sources in Iceland, one of which describes its use to locate the Sun in a completely overcast sky. Sunstones are also mentioned in the inventories of several churches and one monastery in 14th–15th-century Iceland and Germany.