When was planet Earth discovered, and who named it?

Lord Frieza did, and it is pronounced Eee-Arth.

This took be aback for a minute! Off the top of my head I say Caperneious (sp), but I’m sure other cultures suspected as much before then.

earth (n.)

Old English eorþe “ground, soil, dirt, dry land; country, district,” also used (along with middangeard) for “the (material) world, the abode of man” (as opposed to the heavens or the underworld), from Proto-Germanic *ertho (source also of Old Frisian erthe “earth,” Old Saxon ertha, Old Norse jörð, Middle Dutch eerde, Dutch aarde, Old High German erda, German Erde, Gothic airþa), perhaps from an extended form of PIE root *er- (2) “earth, ground.”

Only Loli is capable of answering this question authoritatively. They were probably there.

Stone Age a guy named Rock tripped on a root landed on his face, got up and spit out the dirt and said, “EERF.” Translated to Earth during the Bronze Age.

They just called it “the ground.”

First man on earth would have, by default, discovered the planet.

This is a reasonable question. At what point did people realize that the Earth is a planet? The Greek mathematician Eratosthenes knew that the Earth was spherical and gave a good approximation of its circumference using shadow lengths.