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,
1928 Isle of Man TT held in heavy rain and mist. The bad race conditions produced many retirements and a slow average speed. The eventual winner of the 1928 Senior TT Race was Charlie Dodson, riding a Sunbeam motorcycle, in 4 hours, 11 minutes and 40 seconds, at an average speed of . 1928 Isle of Man TT In the 1928 Isle of Man Tourist Trophy the newly developed 'positive-stop' foot gear-change by Velocette gave Alec Bennett his fifth TT Race win in the 1928 Junior, in the time of 3 hours, 50 minutes and 52 seconds, at an average speed of , and setting