“Ancient Space Dust Hints at a Mysterious Period in Earth’s Early History”
by Rebecca Boyle
The Atlantic, May 11, 2016
There’s a paper in Nature about space dust, in the form of a fossil micrometeorite from 2.7 billion years ago. And it is upending our ideas about Earth’s ancient atmosphere. Scientists have thought ancient Earth had paltry levels of oxygen, but this mote of space dust says opposite. When it plummeted to Earth during the Archaean era, the iron in the space dust turned to rust. For this to have happened, oxygen concentrations in the upper atmosphere would need to be close to modern levels, which is against long-held scientific belief. How did Earth get so much oxygen before the evolution of photosynthetic plants? It’s a good question. That paper is embargoed til Wednesday.