Comet Dust Makes Mercury A Dark Planet
Carbon from dissolving comets has stained Mercury black.
Mercury's dark surface has always been a mystery to scientists. It had been thought that the planet's thin coating of dark iron nanoparticles - the result of bombardment from solar wind and micrometeorite impacts - was the reason.
But recent data suggests Mercury's surface contains very little of those dark nanoparticles. So Dr. Megan Bruck Syal, a post-doctoral researcher now at Lawrence Livermore National Laboratory in California, hypothesized that dust from passing comets was hitting and sticking to the surface of Mercury.
Impact models confirmed this theory. As comets near the Sun, they begin to break apart, and much of the resulting dust is carbon, which makes the surface of the planet darker.
Related Links
- Paper in Nature Geoscience
- Brown University release
- Lawrence Livermore National Laboratory release
- EarthSky story