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,
1920 Isle of Man TT 44 minutes and 6 seconds, an average speed of 51.36 mph. A mechanical retirement for Eric Williams allowed Cyril Williams also riding an AJS to build up an impressive lead of 20 minutes. However, Cyril Williams hit transmission problems at Creg-ny-Baa and free-wheeled and pushed it for the last five miles to win by a margin of 9 minutes and 50 seconds from J.A.Watson-Bourne, riding for Blackburne motorcycles in 4 hours, 37 minutes and 57 seconds, at an average race speed of 40.74 mph. The Lightweight class within Junior race was won by R.O Clarke riding a Levis and he