What Caused the Ice Ages?

The empirical facts are confronted with two theories.The usual attempt to explain the Ice Ages is based on two phenomena.First, the other planets of the solar system induce small and slow variations of Earth's orbit.They were introduced by Milankovich (Milankovitch, 1941).They lead to variations of the insolation on Earth.Secondly, various feedbacks in Earth's climate system are considered.An example of a positive feedback: cold brings snow, which reflects solar light efficiently, so that the temperature decreases.The question is, whether the feedbacks are large enough to produce the Ice Ages.The small quasi periodic changes of Earth's orbit follow directly from the laws of mechanics and gravity; they are not questioned.Milankovitch cycles in the climate should belong to any climate model.The problem is the size of the feedbacks, which at present produce our regular climate.This model of the Ice Ages, often simply called "the Milankovitch theory", is used by practically all members of the scientific community for the interpretation of the data.The second theory, which has been developed by us, involves a very unusual astronomical action on Earth's climate system during the last 3 million years.The revealing observation is an asymmetry with respect to the present North Pole: when the glaciation was at its maximum, it reached the region of New York City, while East Siberia remained ice free.Evidently, the North Pole was in Greenland.Therefore, at the end of the Ice Ages it shifted geographically to its present position in the Arctic Sea.This involves a motion of the globe, not of the rotation axis.We claim that there are circumstances in which this is compatible with laws of nature and observations.A planetary object with a mass at least 1/10 of Earth's mass must pass very close to Earth.We shall call this planet "Z".The tidal forces induce a 1 per mil stretching deformation of Earth's globe.While this relaxes in a time of order one year the pole moves.Since Z has disappeared, it must have disintegrated and the fractions evaporated.By necessity, Z was hot, liquid and radiant.It moved in an extremely eccentric orbit.Its evaporation created a disk shaped cloud of ions around the Sun.A disk shaped cloud has been postulated by R.A. Muller and G.J. MacDonald (Muller& MacDonald, 1995;1997), since Earth's orbit would be in the cloud with a Milankovitch period In this didactic paper basic features of the Ice Ages will be illustrated using well known data.