Earth's Rotation, Shape and Gravity
|Title||Earth\'s Rotation, Shape and Gravity|
Meeting held in Nice, France, 6 - 11 April 2003. The expanding Earth view is adopted, with the aim to show the links Earth's rotation, time-varying gravity, expansion, can present in shaping our planet. An increasing gravity - whatever the reason may be - must induce an additional J2 variation, towards a decreasing ellipticity. The same effect, in different magnitude order, could be produced by the slow decay of the well know equatorial ca. 100 m. excess flatness of the Earth - due probably to a faster paleo-spin. The combination of these two effects can cause both misinterpretation of some phenomena like the alleged glacial-rebound, and difficulty to recognise the probably small amount (few mm/yr or fraction of mm/yr) of Recent global expansion. The need for a varying Earth's gravity is envisaged as a consequence of an expanding Earth due to cosmological causes, having some signatures in geological records and astrophysical large-scale structure dynamics. Finally the expansion of the Earth - and then an increasing gravity - finds a new support in the forecast of an oscillating path of the True Polar Wander, which has been already observed.