Physical processes occurring in space and in astrophysical objects usually differ significantly from those occurring naturally on earth. In particular, unlike in our everyday experience where we encounter matter as solid, liquid or gas, most ordinary matter in the universe is in the form of plasma. Plasma contains a significant amount of free charged particles, and thus the role of electro-magnetic forces is critical.
Physical processes in space and astrophysical environments occur on macroscopic (waves, shocks, turbulence, reconnection, etc.) and microscopic scales (interaction of particles with electro-magnetic fields, particle collisions, dust formation, etc.). Such processes are interesting to study in their own right, as they often elucidate physics not accessible in the laboratory. They must also be understood in detail as they provide the fundamental building blocks for understanding celestial bodies (stars, planets, comets, etc.) and their interactions.