National Aeronautics and Space Administration

Goddard Space Flight Center

Magnetic forces play a key role in solar storms that can impact Earth's magnetic shield (magnetosphere) and create colorful aurora. Courtesy of SOHO. Original image can be found at http://soho.nascom.nasa.gov/gallery/images/magnetic_clean.html

The largest, single, challenge for astronauts traveling to Mars will be to overcome exposure to solar storms and radiation.