Why does Mars no longer have a magnetic field?
A) Its core cooled and the dynamo effect shut off.
B) Giant impacts slowed the planet's rotation.
C) Mars does not have a dense core.
D) The thin atmosphere can't protect the planet from the solar wind.

Question

Quizplus · Accepted Answer

Mars no longer has a magnetic field primarily because its core cooled down, which in turn stopped the dynamo effect that generates a planet's magnetic field.

Why Does Mars No Longer Have a Magnetic Field