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,
April 2015 lunar eclipse 17 October 1529 (which lasted 1 minute and 42 seconds). Another shortest occurs on December 28 1917, lasting (11 minutes and 58 seconds). The next very short lunar totality will occur on 26 May 2021 (which will last 14 minutes and 24 seconds). This was the sixth total lunar eclipse out of nine with totality under 5 minutes in a five millennium period between 2,000 BC and 3,000 AD. However, due to the oblateness of the Earth, this lunar eclipse may have actually been (barely) a partial eclipse. This eclipsed moon was 12.9% smaller in apparent diameter than the supermoon