I’ve seen (and felt) those textured globes, in which features like the Himalayas can be felt. But I know the elevation and texture are not to scale… if a globe were made with near-perfect to-scale representation of surface features (mountains), would those features be significant enough to be felt by one’s fingers? Does such a globe exist that can be purchased?
No, not unless the globe was of sufficient diameter. My guesstimate is about ten miles or so to be able to feel surface features with your finger.
Someone will be around soon to demonstrate my errors with proper math.
Looks like one of the factoids I learned in Grade 8 actually is true. The earth is smoother than a billiard ball
So the question now would be exactly how large would the globe have to be in order for to-scale topographical features to be felt?
And Kansas is flatter than a pancake.
In my calculations, Mount Everest could easily be felt if the globe were 1 meter in diameter.
Everest = 9 Km high
Earth = 12756 Km in diameter
9/12756 = .0007
.0007 * 1 m = .7 mm
.7mm is about the thickness of a mechanical pencil lead.
Back-of-the-envelope calculations - the most prominent burs or gouges on the surface are a matter of a few miles. Say 5. The Earth is a hair under 8000 miles in diameter, so say you might get local imperfections of 5/8000 or so. For a 1 foot in diameter globe, that’s 0.0075 inch. A large dust particle (100 microns) landing on your globe is the size of a major mountain to scale.
Note that this a slightly different issue than how close to perfectly spherical it is, as in the provided link.
The way I like to understand the relief of the Earth is that Mount Everest is 8.8 kilometres tall and the Challenger Deep is 10.9 km deep, so the total range for Earth elevation is 19.7 km. The Island of Montreal is 50 km wide, so the total elevation variance of the world is only half the width of my city. (It doesn’t span the whole island.) The city, of course, is far smaller than the dot that represents it on most globes would suggest.
Note that Everest starts at a base elevation already considerably above sea level. We have to take this sort of thing into consideration when figuring how much the feature sticks up over the surrounding area. That’s why I gave up and simply said “5 miles or so”, which is probably a bit much. At any rate, I think a meter or two is probably ball park for being able to feel texture to the surface.
As i recall, there is a to-scale globe at the Ontario Science Center. It’s possible to feel the mountain ranges and ocean trenches. The globe was maybe 2” in diameter.
Human touch is much more sensitive than one might think - it’s very easy to tell the difference between one and two sheets of paper, and they are a few thousandths of an inch thick. Also, it’s really easy to feel surface roughness in the micron range.
That’s a pretty small globe. Might as well be a billiard ball.
You should see my Stonehenge model!
I can’t do YouTube at work. For some reason though, I’m pretty confident I know what the clip is!