Physics of Leap Second

The physical origin of the leap second is discussed in terms of the new gravity model. The calculated time shift of the earth rotation around the sun for one year amounts to $\displaystyle{\Delta T \simeq 0.621 s/ year}$. According to the data, the leap second correction for one year corresponds to $\Delta T \simeq 0.63 \pm 0.03 s/ year$, which is in perfect agreement with the prediction. This shows that the leap second is not originated from the rotation of the earth in its own axis. Instead, it is the same physics as the Mercury perihelion shift. We propose a novel dating method (Leap Second Dating) which enables to determine the construction date of some archaeological objects such as Stonehenge.