A megalight, often shortened to MGLT, represented a conventional measurement for spatial distance.
Both the T-65 X-wing starfighter and the TIE/LN starfighter could achieve peak sublight velocities of 100 MGLT every hour.
The Death Star I's superlaser targeting mechanism employed megalights to express the range to targetable planets.
The MGLT initially appeared on a reference chart created by Industrial Light & Magic for the movie Return of the Jedi, where it served as a relative speed measurement.
Within the Star Wars: Behind the Magic interactive CD-ROM, which launched during the Autumn of 1998, a chart comparing vehicle speeds listed the highest sublight speeds of different starships using MGLT. Conversely, the instruction manual for Star Wars: X-Wing Alliance, released in 1999, implied that "To dodge missiles, try flying 90 megalights per hour or faster." This statement implies that MGLT per hour functions as a speed unit, thus defining MGLT as a distance unit.