Capitalize Names of Planets, Stars, and Constellations
Capitalization
Rulebase Summary
Capitalize the names of planets, stars, and constellations — Mars, Jupiter, Milky Way, Polaris, Orion. Do not capitalize sun and moon. Capitalize Earth when it is mentioned alongside other planet names; otherwise lowercase it when preceded by 'the' in general usage.
Examples
A. The probe was launched toward mars and jupiter.
A. The probe was launched toward Mars and Jupiter.
Planet names are proper nouns and are always capitalized.
A. Earth is the third planet from the Sun.
A. Earth is the third planet from the sun.
Sun and moon are not capitalized. Earth is capitalized when used as a planet name alongside others.
Transcript Notes
Do not capitalize 'sun' and 'moon' in general contexts. Capitalize 'Earth' only when mentioned with other planets (Jupiter, Earth, Neptune, Venus) or when personified (Mother Earth) — otherwise lowercase. Capitalize names of planets, stars, and constellations (Mars, Rigel, Orion, Ursa Major).
Style Guide References (4)
Morson's
BGGP
BGGP
BGGP