What is space physics?
When? Mostly during the satellite era, from about 1960
Where? Mainly, the space between and around the solid bodies in space.
In situ (on the spot) measurements of natural processes using spacecraft
Experiments in space (strong radio waves, plasma releases from spacecraft etc.)
Remote sensing measurements (radar, ionosondes, radio telescopes, optical instruments
There are no well defined borders to other sciences. Space physics mainly relates to plasma physics, meteorology (in the upper atmosphere), astronomy and astrophysics (at the sun and other stars).