Sometimes, there is an absolute limit on the number of terms an officeholder can serve, while, in other cases, the restrictions are merely on the number of consecutive terms.
For example, Maxwell's Equations would always be capitalized, while quantum mechanics is usually un-capitalized. I searched half a dozen sites for an answer to this but found no clue about a rule. So go either way that makes you happy, but (most of all) be consistent.
Cenozoic era. Capitalize astronomical terms such as the names of galaxies, constellations, stars, planets and their satellites, and asteroids. However, the terms earth, sun, and moon are often not capitalized unless they appear in a sentence that refers to other astronomical bodies.