The List Planetary Science The sad magnetic state of the solar system’s rocky worlds PLANETARY PROTECTION Earth’s magnetic field deflects charged solar particles toward the planet’s poles, generating auroras. This photo was taken from (and shows parts of) the International Space Station. Above: NASA; Below, from top: NASA, JHUAPL, Carnegie Inst. for Science; JPL-Caltech/NASA; NASA; JPL-Caltech/NASA Share this:EmailFacebookTwitterPinterestPocketRedditPrint By Thomas Sumner September 7, 2015 at 8:00 am 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. Mercury: Paltry The most petite planet has an appropriately puny magnetic field, just 1.1 percent as strong as Earth’s (SN Online: 5/7/15). Venus: Zilch Earth’s nearest neighbor doesn’t generate a planet-wide magnetic field, so the solar wind penetrates and is gradually stripping away the atmosphere. The moon: Lost Magnetized lunar rocks hauled back by Apollo astronauts show that, at some point, the ancient moon had a hefty magnetic field. It has since died out (SN Online: 12/4/14). Mars: Collapsed The Red Planet lacks a global magnetic field today, but magnetized regions of Martian crust point to an ancient magnetic field that eventually fizzled.