Planetary science (rarely
planetology) is the scientific study of
planets (including
Earth),
moons, and
planetary systems (in particular those of the
Solar System) and the processes that form them. It studies objects ranging in size from
micrometeoroids to
gas giants, aiming to determine their composition, dynamics, formation, interrelations and history. It is a strongly
interdisciplinary field, originally growing from
astronomy and
earth science, but which now incorporates many disciplines, including
planetary geology (together with
geochemistry and
geophysics),
cosmochemistry,
atmospheric science,
oceanography,
hydrology,
theoretical planetary science,
glaciology, and
exoplanetology. Allied disciplines include
space physics, when concerned with the effects of the
Sun on the bodies of the Solar System, and
astrobiology.