Lunar day around the Sun at the same time, the Moon must travel further to return to the same phase. On average, this synodic period lasts 29 days, 12 hours, 44 minutes, and 3 seconds. This is the mean figure since the speed of the Earth–Moon system around the Sun varies slightly during a year due to the eccentricity of its elliptical orbit, variances in orbital velocity, and a number of other periodic and evolving variations about its observed, relative, mean values, which are influenced by the gravitational perturbations of the Sun and other bodies in the Solar System. As a result,
Apollo 15 operations on the Lunar surface triangles are panorama stations. Apollo 15 operations on the Lunar surface Apollo 15 lunar surface operations were conducted from July 30 to August 2, 1971, by Apollo 15 Commander David Scott and lunar module Pilot James Irwin, who used the first lunar rover to make three exploratory trips away from their landing site at the base of the Apennine Mountains, near Hadley Rille. They collected a total of of lunar surface material during 18½ hours outside their lunar module, "Falcon". At 104 hours, 30 minutes and 12 seconds GET the descent engine of "Falcon" ignited. Burning at about 10% for