Only capitalize the names of school subjects if they are languages or specific names of classes.
English, language arts, math, Algebra 1, science, Biology 101, history, U.S. History to the Civil War
Capitalize the names of classes (groups of students) only when they are part of the name of something else.
Ana is going to be a junior next year.
The junior class sponsors the Senior Prom each year.
Capitalize the names of historical events, periods, and documents. Primeval and medieval are adjectives but are not capitalized. 20th century and other centuries are not capitalized).
War of the Roses, Civil War, Magna Carta, Bill of Rights, Dark Ages, Middle Ages, Renaissance
Capitalize the names of special events, awards, and degrees.
Spring Soiree, Academy Award, Language Arts Award, Bachelor of Science (not bachelor's degree, which could be any degree at that level)
Capitalize the names of planets and universal bodies.
Venus, Polaris, Halley's Comet, Milky Way
Note: If you think about the history of astronomy, as people noticed planets, stars, and later moons and other objects in the universe, they gave them names. Strangely, no one ever named our sun, our moon, or our planet! Therefore, we don't capitalize sun and moon when we refer to ours. That would be like capitalizing student when referring to you. We only capitalize earth when we are using it as the name of the planet, usually in context with other planet names. (We usually put the in front of earth when it is not capitalized.)
The sun rises in the east and sets in the west.
The moon affects the tides as it waxes and wanes.
Dinosaurs no longer roam the earth.
Mars takes longer to circle the sun than Earth does.