| MadSci Network: Astronomy |
I think magnetic fields are necessary for life because they shield planets and life from harmful radiation. One of the latest NASA press releases states that "Earth's shield absorbs space-storm energy by throwing some of its charged particles into space...If the Earth had no global magnetic field, or magnetosphere, the solar wind would impact the atmosphere directly and gradually erode it. Instead, the solar wind slams into Earth's magnetosphere and is diverted around the planet (1)." The atmosphere, of course, has its own useful purposes for life. Charged particles necessary for life, such as sodium, calcium, and phophorus, are influenced by the magnetic field (2), and the planet's liquid core, which is partly responsible for the magnetic field, also causes volcanic events, hydrothermal events, and plate tectonics - all things usually associated with life-supporting planets. Not all planets have magnetic fields, though. Currently, Jupiter, Saturn, Earth, and Mercury have fields which extend beyond the planets themselves (3), and Mars only shows remnants of what once was (4). Today, Mars' magnetic field is weak and almost non-existant (5). (1) NASA Press Release 02-84, "Earth's space-storm shield offers protection - at a price". (2) Prekash Joshi, RPI NSCORT program, personal communication. (3) http://galileo.jpl.nasa.gov/jupiter/magnetic_field.html (4) http://mars3.jpl.nasa.gov:80/mgs/sci/mag/data1/mag_first.html (5) http://mars3.jpl.nasa.gov:80/mgs/sci/mag/mag.html More information on all the planets can be found at http://seds.lpl.arizona.edu/nineplanets/nineplanets/nineplanets.html
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