No, not that kind of snow, but scientists say deep inside the planet Mercury, iron â€œsnowâ€ forms and falls toward the center of the planet, much like snowflakes form in Earthâ€™s atmosphere and fall to the ground. The movement of this iron snow could be responsible for Mercuryâ€™s mysterious magnetic field, and Mercury may be the only body in our solar system where this occurs.
Mercury and Earth are the only local terrestrial planets that possess a global magnetic field. But Mercury’s is about 100 times weaker than Earth’s, which scientists have been unable to explain.
Made mostly of iron, Mercuryâ€™s core is also thought to contain sulfur, which lowers the melting point of iron and plays an important role in producing the planetâ€™s magnetic field.
To better understand the physical state of Mercuryâ€™s core, the researchers in a lab recreated the conditions believed to exist at Mercury’s core, and melted an iron-sulfur mixture at high pressures and high temperatures.
In each experiment, an iron-sulfur sample was compressed to a specific pressure and heated to a specific temperature. The sample was then quenched, cut in two, and analyzed with a scanning electron microscope and an electron probe microanalyzer.
As the molten, iron-sulfur mixture in the outer core slowly cools, iron atoms condense into cubic â€œflakesâ€ that fall toward the planetâ€™s center, said Bin Chen, University of Illinois graduate student and lead author of a paper published in the April issue of Geophysical Research Letters. As the iron snow sinks and the lighter, sulfur-rich liquid rises, convection currents are created that power the dynamo and produce the planetâ€™s weak magnetic field.
The researchers say their findings provide a new context for the data that will be obtained from NASA’s MESSENGER spacecraft, which will flyby Mercury for a second time on October 6, 2008. It will pass by the planet again in September of 2009, and go into orbit in March of 2011.
Original News Source: Eureka Alert
Here are some interesting facts about Mercury.