Above: NASA; Below, from top: NASA, JHUAPL, Carnegie Inst. for Science; JPL-Caltech/NASA; NASA; JPL-Caltech/NASA
A powerful global magnetic field envelops Earth in a cozy blanket of protection against bursts of solar particles (see "The magnetic mystery at the center of the Earth"). But the solar system’s other rocky worlds aren’t so lucky.
The most petite planet has an appropriately puny magnetic field, just 1.1 percent as strong as Earth’s (SN Online: 5/7/15).