Earth has a radius more than 6000 km, so if we wanna see the whole Earth as a small circle, it would be a good idea to get away from it thousands of kilometers and more.
Unfortunately, Mount Everest, even though it’s our highest mountain, is less than 10 km tall, so it’s like nothing if we compare it to the size of Earth.
Commercial planes fly around 10 km above Earth, which is slightly higher. But it’s still practically on the surface. The diameter of Earth is over 10 000 km, so anything in the slim 10 km zone around the massive ball is practically on the surface, even if it’s not touching it.
The diameter of Earth is 12 756 km and let’s say that planes fly exactly 10 km high. That is ratio 12756:10 or 1275.6:1. Let’s say you measure 1.65 m and something is hovering over you 1.65/1275.6=0.0013 m far away from you. That is 1.3 millimetres. If something is 1 mm away from your skin, it’s almost on your skin. Now imagine a 1.65 m wide ball (it has your height, but it is also wide that much) and some bug is on it and it is looking at it and his eyes are 1.3 mm above the ground. It would see almost nothing from the whole ball. And it would see a horizon that looks flat.
For comparison: The Moon is 384 400 km away from our planet, so from the Moon we would see easily how the Earth looks from space.
Links:
- Wikipedia: Mount Everest
- FlightDeckFriend.com: How Hight Do Planes Fly?
- Royal Museums Greenwich: How far away is the Moon?