About 4.6 billion years ago a giant cloud of hydrogen gas and dust collapsed under its own weight eventually turn into a disk called the solar nebula. Most of this interstellar material is concentrated in the center of the disk formed the Sun, while part of the remaining gas and dust of the solar nebula went into the formation of planets and other objects in the Solar system (SS).
Today, scientists from mit (Massachusetts Institute of Technology, MIT), USA, together with colleagues from other scientific organizations have evaluated the lifetime of the solar nebula is a key stage of evolution of the SS, during which it proceeded, a large number of structure-forming processes.
Measuring the orientation of the weak residual magnetic fields in the mineral angrite included in the composition of samples of ancient meteorites, formed approximately 4,653 billion years ago (about 4 million years after the formation of the SS), the scientists led by Hapem WAN (Huapei Wang) of MIT has determined that demagnetise these samples of the ancient magnetic field induction was not higher than 0.6 microtesla. Previous studies that examine the remanence of the substance of meteorites, formed 2-3 million years after the formation of our planetary system have shown that its value corresponds to the ancient magnetizing field induction of about 5 to 50 microtesla, that is, in that period of history it was approximately 10-100 times more powerful than 1-2 million years later. According to the theory it is a characteristic sign of the collapse of the solar nebula, so Wang and his team conclude that the solar nebula has disappeared almost completely after 4 million years after the formation of the SS.
According to this new assessment of the gas giants Jupiter and Saturn were formed during the first 4 million years after the formation of the SS. Moreover, by that time, was to end all migration of these planets in the SS.