The presence of a Mercurian magnetic field surprised the planetary scientists on the Mariner 10 team because:
A) Mercury is low in iron.
B) Mercury spins to rapidly to produce a stable dynamo.
C) It's still too hot for its core to have differentiated.
D) The dynamo theory predicted that Mercury was spinning too slowly for one.
E) Mercury lacks an iron core.

Question

Quizplus · Accepted Answer

The dynamo theory suggests that a planet needs a certain rotational speed to generate a magnetic field. Mercury's slow rotation was thought to be insufficient for this, making the presence of a magnetic field surprising.

The Presence of a Mercurian Magnetic Field Surprised the Planetary