How long were days during the Jurassic period?
“It is well known that the rotation of the Earth is slowing down, due primarily to tidal friction in the Earth-Moon system. This means that the days are getting slowly longer, and there are fewer of them in a year, since slowing of the Earth’s rotation does not affect its orbital period about the Sun (the length of a year remains constant, but the length of a day changes). Current estimates of the long-term rate of change of the length of day, based on several kinds of astronomical evidence ranging from ancient observations of eclipses to modern observations using Very Long Baseline Interferometry, are on the order of 2 milliseconds per day per century – that is, the day is 2 milliseconds longer than it was a century ago.” So a hundred thousand years ago the days would have been 2 seconds shorter. A hundred million years ago they would have been about 2000 seconds shorter, assuming the variation is linear, which it probably isn’t. 2000 seconds is 33.3 minutes. So a bit over half an hou
