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Evolution of the Solar System

2 May 2012

At http://phys.org/print255086031.html … the solar system, it is thought, is over 4 billion years of age – but its formation may have occurred much quicker than realised, until now. A team of researchers at the Hebrew University in Jerusalem, aided by laboratories in Japan and the US, have come to this conclusion as a result of nucleus samarium-146 (146Sm) dating methodology. However, one can see there are a number of caveats – if not elephants in the room. They say 146Sm belongs to a family of nuclear species which were 'live' in our Sun and its solar system when they were born. The dating technique depends on the amount of 146Sm left in various mineral archives until finally expiring. In fact 146Sm has become the main tool, in recent years, for establishing 'time evolution' of the solar system over the last few thousand million years. This is partly due to the nature of the element samarium –  a rare element in nature.

In a recent article in Science the half life of 146Sm has been newly determined, from 103 million years to a much shorter 68 million years. Such a shortening of half life values thereby shrinks the chronology – including events in the solar system. The new solution, it is said, is now consistent with a recent and supposedly 'precise' dating of a lunar rock – and in general is in agreement with dating from other chronometers. So what caused the change of heart, we might wonder – being naturally suspicious. Was 146Sm embarassingly out of step with other dating clocks? If so, did the need for a revision of the 146Sm method come first, and the how and why-for, somewhat later? Does any of this matter if the Sun is not hot as a result of nuclear reactions somewhere in its innards, and how might a different kind of Sun affect nuclear based dating methodologies?

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