Massachusetts Institute of Technology | 2015 Jan 14
New study finds meteorites were byproducts of planetary formation, not building blocks.
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: These bodies smashed together with such violent force that they melted a fraction of their material, and shot a molten plume out into the solar nebula. Residual droplets would eventually cool to form chondrules, which in turn attached to larger bodies — some of which would eventually impact Earth, to be preserved as meteorites. ...
Impact jetting as the origin of chondrules - Brandon C. Johnson et al
- Nature 517(7534) 339 (15 Jan 2014) DOI: 10.1038/nature14105