The Sun has an orbit that is a result of the orbits of the outer planets. The diameter varies with time but has an average period of 11 years and varies between 200,000 km and 2 million km. This orbit is about the center of gravity of the solar system and repeats itself every 178.8 years. The earth is in orbit about the center of the sun and repeats itself every year. Thus the earth and its orbit about the sun have the additional motion of the sun’s motion about the center of gravity of the solar system. This motion affects the rate of rotation of the earth measured by the length of day [LOD].

The LOD is affected by El Nino-Southern Oscillation [ENSO] and the quasi-biannual oscillation [QBO]. This paper will demonstrate that the LOD is affected by the orbit of the Sun thus raising the question: “Is the relation between LOD and ENSO caused by ENSO, causes ENSO or both?