Sounds like a stupidly easy question to find out with a quick internet search, but it’s not.
I don’t want to know the average surface temperature, or the average ocean surface water temperature, or read another article about climate change.
But that’s all I found in the past hour.
I’d like to know the average temperature of all molecules that comprise earth, or a best guess scientific estimate.
I mean OP asked for average, that’s how average calculated 🤷
Median is impossible to calculate since you need a whole array of data to know what’s in the middle. I think anything other than that is impossible because we need gazillion of data to even getting close to the accurate answer, that’s why all answer out there is usually categorised and in estimate.