Did Earth form in flash of galactic lightning?

摘要

Giant lightning strikes that were triggered by gamma-rays could have led to the formation of meteorites and rocky planets such as Earth. The lightning spanned the early solar system and fused grains of dust into spheres that became the seeds for larger objects. Meteorites that formed early in the history of the solar system are rich in chondrules - beads of once-molten rock that are thought to have formed from dust exposed to temperatures of about 2000℃. But no one is quite sure how this happened. "It is a very complex problem," says Brian McBreen of University College Dublin in Ireland, "but somehow nature has done it."