The line between lunar day and night creeps along the Moon's equator at about 15 kilometres an hour, and much slower nearer the poles.

It follows from a 10,900-kilometre circumference and a 29.5-day day. At the equator you would need a bicycle to stay in the sunlight; at 60 degrees north or south a brisk walk would do it. Rover missions that need continuous solar power have been designed around exactly this arithmetic.