Noun
the period of time taken for the moon to make one full rotation on its axis (about 27.3 sidereal days)
Source: WordNetIts period is about 12 hours and 25.2 minutes, exactly half a tidal lunar day, which is the average time separating one lunar zenith from the next, and thus is the time required for the Earth to rotate once relative to the Moon. Source: Internet
The rover would run during the lunar day, stopping occasionally to recharge its batteries via the solar panels. Source: Internet
The vehicle was powered by batteries which were recharged during the lunar day by a solar cell array mounted on the underside of the lid. Source: Internet