http://www.scientificamerican.com/article/bad-weather-makes-day-long/ reminds us that the earth is largely 'fluid' ... ... moving atmosphere, oceans, core and often, solid rock, some 'incoming'. A big earthquake can change the length of the day by a few thousandths of a second. Here at UoReading Meteorology, they even bet on the length of the next day, given the forecast weather. Guy