That's a good point. Perhaps we need to just use things that are well understood.
The moon is about 350,000 to 400,000 km away. By my estimate (of other people's estimate), we're looking at a spot in the sky roughly the size of a dime (US 10-cent coin) on the moon.
I think my reptilian brain understands the distance of the moon and the size of a dime.
Hmm. My inner eye can’t really get a handle on the distance to the moon. I know it’s 33 Earth-diameters away, that it’s 400 times further than my longest cycle ride, but my mind somehow keeps shortening every distance longer than I can go in a day under my own power to similar levels of “quite far”.
You can get a sense of scale from mountain landscapes or city skylines. As you get closer to the city, you get a better sense of scale and size based off of how much the city has grown or shrunk.
The moon is very far away, but it DOES grow and shrink as it comes closer and further away from us. Using the size differential, you can get an innate feel to the size of the moon. Technically speaking, just driving towards (or away from) the Moon will have you traveling closer / further away from it, and give you a sense of scale.
The next time you drive to a major city or large, recognizable landscape, keep an eye on how big and small mountains (or buildings) are and how quickly they move parallax to the foreground. It really does give an instinctive sense of scale. Train this instinct well enough, and you can use it on the moon.
The trouble with driving (or trains) is that my unthinking processing treats the speed as constant and shrinks the distances. Even cycling 1080 km along the Rhine, from the North Sea to the Swiss not-quite-Alps had that foreshortening, though to a lower degree.
The moon is about 350,000 to 400,000 km away. By my estimate (of other people's estimate), we're looking at a spot in the sky roughly the size of a dime (US 10-cent coin) on the moon.
I think my reptilian brain understands the distance of the moon and the size of a dime.