The earth's days are getting longer without normal noticing, it would take 3.3 million years to gain just one minute.
The average day over past 27 centuries has lengthened at a rate of about +1.8 milliseconds s) per century.
According to the study it shows that this was "significantly", than the rate of 2.3 ms per century previously estimated - requiring a mare 2.6 million years.
The study lead co-author Leslie Morrison a retired astronomer said "its a very slow process".
The researchers use gravitation theories about the movement of the Earth around the Sun, and the Moon around the Earth, to compute the timing of eclipses of the Moon and Sun over time. The team found discrepancies between where the eclipses should have been observable, and where on earth they were actually seen.