The aurora provide information
about the composition of the Earth's atmosphere (we will return to that later), but what
else can be learned?
First, recall that the presence of aurorae
in the polar regions is a result of a dipole magnetic field (one like a bar magnet).
The presence of a planetary magnetic field requires the planet to have a
fluid, conducting, rotating core!
In other
words, the presence of aurorae in a planet's (magnetic) polar atmosphere indicates the
planet has a a fluid, conducting core!
