It includes the topics of aeronomy, aurorae, planetary ionospheres and magnetospheres, radiation belts, and space weather (collectively known as solar-terrestrial physics[1]).
It is studied using direct in situ measurements by sounding rockets and spacecraft,[2] indirect remote sensing of electromagnetic radiation produced by the plasmas, and theoretical magnetohydrodynamics.
Gauss and William Weber made very careful measurements of Earth's magnetic field which showed systematic variations and random fluctuations.
In the late 1870s, Henri Becquerel offered the first physical explanation for the statistical correlations that had been recorded: sunspots must be a source of fast protons.
Space physics began in earnest with the first in situ measurements in the early 1950s, when a team led by Van Allen launched the first rockets to a height around 110 km.