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Wednesday, November 19, 2014


Meteorite Grains Tell Shocking Tale of Solar System Birth

By Jonathan Cheng

The most accurate laboratory measurements yet made of magnetic fields trapped in grains within a primitive meteorite are providing important clues to how the early solar system evolved. The measurements point to shock waves traveling through the cloud of dusty gas around the newborn Sun as a major factor in solar system formation. The results appear in Science. The lead author is graduate student Roger Fu of MIT, working under Benjamin Weiss; Steve Desch of Arizona State Univ.'s School of Earth and Space Exploration is a co-author of the paper. "The measurements made by Fu and Weiss are astounding and unprecedented," says Desch. "Not only have they measured tiny magnetic fields thousands of times weaker than a compass feels, they have mapped the magnetic fields' variation recorded by the meteorite, millimeter by millimeter." Construction debris It may seem all but impossible to determine how the solar system formed, given it happened about 4.5 billion years ago. But making the solar system was a messy process, leaving lots of construction debris behind for scientists to study. Among the most useful pieces of debris are the oldest, most primitive, and least altered type of meteorites called the chondrites. Chondrite meteorites are pieces of asteroids, broken off by collisions, that have remained relatively unmodified since they formed at the birth of the solar system. They are built mostly of small stony grains, called chondrules, barely a millimeter in diameter. Chondrules themselves formed through quick melting events in the dusty gas cloud – the solar nebula – that surrounded the young Sun. Patches of the solar nebula must have been heated above the melting point of rock for hours to days. Dustballs caught in these events made droplets of molten rock, which then cooled and crystallized into chondrules.