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The Solar System formed 4.6 billion years ago, from a cloud of gas and dust called the solar nebula. The centre of the nebula was so hot and dense that nuclear reactions began and the Sun was formed. The remaining gas and dust rotated and churned vigorously. At Jupiter�s orbit this caused regions of high pressure and radiation, called shocks, which spread to the inner Solar System.
When the shock front hit tiny particles in the orbit of the asteroid belt (between Mars and Jupiter) the particles melted, forming droplets called chondrules.
It has been known for some time that the tiny glass-like spheres found in meteorites must have been formed by shock waves. No one could explain the source of the shocks until now. These results show a shock wave originating at Jupiter�s orbit would have had the pressure necessary to melt particles in the asteroid belt.
�This calculation has probably removed the last obstacle to acceptance of how chondrules were melted,� remarked Steven Desch of Arizona State University, USA, who showed shock waves could have formed the droplets. �Meteoriticists have recognized that the ways chondrules are melted by shocks are consistent with everything we know about chondrules. But without a proven source of shocks, they have remained mostly unconvinced about how chondrules were melted. [This research] demonstrates that our early solar nebula experienced the right types of shocks, at the right times, and at the right places in the nebula to melt chondrules.�
The chondrules have since been incorporated into larger objects, and can still be seen in some meteorites, known as chondrites.
More info: Arizon State University
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