It's a blog! Mainly of book reviews.
Skipped the stuff on the geo-dynamo (origin of Earth's magnetic field) - interesting but not urgent. Alfven waves are qualitatively straight-forward; imagine plucking magnetic field lines like they are guitar strings! Of course the field must be embedded in a moving plasma. Magnetostrophic waves on the other hand, are clear as mud. They can occur when the magnetic field is rotating in relation to the plasma.