A twist on planetary origins
Meteors that have crashed to Earth have long been regarded as relics of the early solar system. These craggy chunks of metal and rock are studded with chondrules — tiny, glassy, spherical grains that were once molten droplets. Scientists have thought that chondrules represent early kernels of terrestrial planets: As the solar system started to coalesce, these molten droplets collided with bits of gas and dust to form larger planetary precursors. However, researchers at MIT and Purdue University have now found that chondrules may have played less of a fundamental role. Based on computer simulations, the group concludes that chondrules were not building blocks, but rather byproducts of a violent and messy planetary process. The team found that bodies as large as the moon likely existed well before chondrules came on the scene. In fact, the researchers found that chondrules were most likely created by the collision of such moon-sized planetary embryos:...