International standards and resources
The International Astronomical Union (IAU) provides comprehensive information on naming, abbreviations and capitalisation for celestial bodies(Opens in a new tab/window).
Australian conventions and resources
The Astronomical Society of Australia(Opens in a new tab/window) follows the IAU usage for naming, capitals and so on. The Geoscience Australia(Opens in a new tab/window) website is also useful.
Use initial capitals for the names of planets and their satellites (‘moons’), constellations, asteroids, specific meteor showers, comets, stars, and other unique celestial bodies:
Saturn Triton [a satellite] Orion C/1995 O1 (Hale-Bopp) the Milky Way the Solar System Polaris the Southern Cross 878 Mildred [an asteroid] the Arietids [a meteor shower] the Horsehead Nebula
Use initial capitals for Earth, Moon and Sun when used in an astronomical context or publication. When referred to more generally, use lower case. When referring to Earth, do not use an article (the):
Earth has one satellite – the Moon.
Mercury is the planet closest to the Sun, followed by Venus and Earth.
The sun rises every morning; sometimes, the moon is visible.
Seeds were planted in the earth.
When these proper nouns are used adjectivally, use lower case:
solar storm lunar eclipse
Use initial capitals for the names of space programs: