Jupiter was the mighty chief of the gods in ancient Rome's pre-Christian religion. It was also said that Rome's legendary founders, Romulus and Remus, were the children of the warlike god Mars, himself Jupiter's son.
Astronomy has always been popular with those who study the capital "C" Classics. Seven out of the eight planets in our solar system were named after Greek or Roman deities. You're living on the only exception to that rule.
The word "earth" has roots in the Old English term "eorþe." Eorþe had multiple meanings like "soil," "dirt," "ground," "dry land" and "country."
Yet the story didn't begin there. Old English is the earliest known phase of what became our modern English tongue. Used until about 1150 C.E., it evolved from a parent language that scholars call "Proto-Germanic."
The German that's spoken today is part of the same linguistic family. "Earth" and "eorþe" are therefore related to the modern German word "Erde." Not only is this the German language's name for our home planet, but it can also be used to refer to dirt and soil.
Our dear Earth has relatives in some other languages, too. For example, there's the Old Saxon "ertha," the Old Frisian "erthe" and the Dutch word "aarde." All these likely descend from a Proto-Germanic term that was never recorded. (As far as we know.)
Nevertheless, linguists have been able to go back and reconstruct this mystery word. Spelled "ertho" in scholarly texts, it's always preceded by an asterisk. This asterisk acknowledges the lack of written confirmation that the word was really used.
Nobody knows when people started using words like "Earth" or "Erde" to refer to the planet as a whole and not just the ground they walked on.
Back in 1783, German astronomer Johann Elert Bode named the seventh planet from our sun "Uranus" (after a Greek god). And though Pluto is no longer considered a planet, we know that 11-year-old Venetia Burney named it in 1930.
But if a single person gave planet Earth its English name — which is unlikely to say the least — his or her identity has been lost to the sands of time.
Still, it's clear that while Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune all started out as the proper names of ancient gods, "Earth" did not. That's why our planet is sometimes called "the earth" with a lowercase "e."
However, according to the University of Oxford Style Guide, the word "Earth" should be capitalized when one is "referring to the name of the planet but not when referring to the ground/soil etc."
What a capital idea!