He is talking about his language, so why are you correcting him? I am sure he knows better what it is in his own language than someone that doesnt even know what language he is talking about.
In my many languages there is overlap between the words, earth, soil, ground, land. And in cases it could be misinterpret you would use world or planet instead of earth, (and country in stead of land for instance).
In (old) english aswell earth used to mean ground, soil, like the other germanic languages, its meaning just has come mainly mean the planet.
"When hell freezes over" reminded me....this group of people from Minnesota are in hell, and are just having a grand ol' time. The devil finds this annoying, and is told that the people are so used to frigid temperatures, that they are absolutely loving the new climate. The devil figures he'll straighten them all out and has every heat source shut down and every last fire extinguished and drops the temperature well below zero. The folks from Minnesota begin to look around and see frost on everything, and icicles hanging everywhere and they start yelling and shouting in jubilation even more boisterously than before, as this could mean only one thing! The Vikings must have just won the Super Bowl.
Maybe because it doesn't seem very logical. I know that isn't what makes an idiom an idiom, but it's true. The snowball (or snowflake) version is way better.
In my many languages there is overlap between the words, earth, soil, ground, land. And in cases it could be misinterpret you would use world or planet instead of earth, (and country in stead of land for instance).
In (old) english aswell earth used to mean ground, soil, like the other germanic languages, its meaning just has come mainly mean the planet.
Unless this is another case of differences between American and British English