capitalization: astronomical terms

Capitalize the names of planets and other astronomical bodies and configurations:

• Venus
• Alpha Centauri
• the Great Bear
• the Milky Way

Exception: Capitalize earth, sun and moon only when they are mentioned in relation to other planets or heavenly bodies:

• The sun shines brightly.

but

• Mercury is closer than the Earth to the Sun.

Do not capitalize generic words forming part of the name of a celestial object:

• Halley’s comet
• the rings of Saturn