Does Mars Have a Magnetic Field? Mars does not have a significant magnetic field, though scientists believe it once did. In 1998, the Mars Global Surveyor detected sporadic magnetic fields around the southern hemisphere of Mars. However, these magnetic fields were fragile and short-lived compared to the Earth’s. [“Solar wind ripping chunks off Mars .” COSMOS magazine]
Earth’s Magnetic Field
Photo Courtesy: NASA/GSFC
One of the main reasons Earth can support life is because of its magnetic field. Unlike Mars, Earth is surrounded by a magnetic field, which repels powerful solar radiation that would strip away the atmosphere. By comparison, the atmosphere surrounding Mars is less than 1% as dense as Earth’s atmosphere because it lacks magnetic protection. [“The Solar Wind at Mars.” – NASA Science] Earth’s magnetic field is generated by molten iron and nickel convection currents in the outer core. Differences in core temperature and the rotation of the Earth continually stir these electrically conductive fluids and generate a strong magnetic field. [“Earth’s Inconstant Magnetic Field” NASA Science]
According to NASA’s Jet Propulsion Laboratory, “The various Martian magnetic fields do not encompass the entire planet and are local (right image). The Martian dynamo is extinct, and its magnetic fields are “fossil” remnants of its ancient, global magnetic field.”
Martian Magnetic Field
Photo Courtesy: NASA/JPL
Although Mars rotates like Earth, scientists believe it lacks sufficient convection within its core to sustain magnetism. Density measurements of Mars indicate that its molten iron core may have cooled much faster than Earth’s. This could be due to massive asteroid collisions, which occurred early in the planet’s history. Scientists recently discovered a 2,000-mile-wide crater on the surface of Mars, the remnant of an asteroid impact several times bigger than the one that killed the dinosaurs on Earth. Four other collisions of similar magnitude are known to have occurred around 4.1 billion years ago, and it’s believed they disrupted the convection within Mar’s core, snuffing out its magnetic field. In the aftermath, Mars became the planet we know today: cold, inhospitable, and geologically dead. [“Supergiant- Asteroid Shut Down Mars’s Magnetic Field.” National Geographic]
