Book 21, Question 66
Why Did Mars Lose Its Magnetic Field?
Mars once had a magnetic field, a bit like Earth's. Today it is gone. Old magnetism is still locked in some Mars rocks. Mars is small, so it cooled faster than Earth.
More fun facts
- Mars lost its global magnetic field billions of years ago.
- The leading idea is that its molten metal core cooled and hardened, so the field faded.
- Without that protection, Mars lost its liquid water.
- Mars still has strong magnetic patches in its crust.
- A compass on Mars would point from one magnetic patch to another instead of to a pole.
Sources: NASA Science, NASA, NASA, NASA
Questions kids ask
Could you use a compass on Mars?
Not well. It would point haphazardly from one magnetic patch to another, because Mars has no global field.