Physicists re-writing the history of solar system?

Washington: The early days of our solar system might look quite different than previously thought, claim physicists. 

In its research, a team at the US Department of Energy's Argonne National Laboratory used more sensitive instruments to find a different half-life for samarium, one of the isotopes used to chart the evolution of the solar system. 

"It shrinks the chronology of early events in the solar system, like the formation of planets, into a shorter time span," said team leader Michael Paul in the 'Science' journal. 

"It also means some of the oldest rocks on Earth would have formed even earlier -- as early as 120 million years after the solar system formed, in one case of Greenland rocks," he added. 

According to the research, everything in our solar system formed from star dust several billion years ago. Some of this dust was formed in giant supernovae explosions which supplied most of our heavy elements. One of these is samarium-146. 

Samarium-146 is unstable and occasionally emits a particle, which changes the atom into a different element. 

Using the same technique as radiocarbon dating, scientists can calculate how long it's been since the Sm-146 was created. Because Sm-146 decays extremely slowly -- on the order of millions of years -- many models use it to help determine the age of the solar system. 

The number of years it takes for an isotope to decrease by half is called its half-life. Since Sm-146 emits particles so rarely, it takes a sophisticated instrument to measure this half-life.