Leonardo da Vinci designed a compass using a magnetic needle for navigation and directional measurement.
Magnetic compasses rely on a magnetized needle aligning approximately with Earth’s magnetic field. Leonardo studied magnetic behavior and incorporated directional instruments into his wider investigations of travel, mapping, and engineering. A compass could help establish bearings when landmarks were unavailable or difficult to see.
Leonardo’s compass work should not be confused with the invention of magnetism or the first compass itself. Compasses were known in Europe and Asia before Leonardo’s lifetime. His contribution was to study, depict, and improve instruments within his broader engineering practice. An astrolabe, by contrast, is primarily used for measuring the positions of celestial bodies.