How far away can an object be before it dips below the horizon and is no longer visible?
For simplicity, treat the planet like a smooth perfect sphere, and ignore the atmosphere and any other obstacles.
Table of Examples
Assume that your eyes are 1.8 meters above the surface of an earth-sized sphere. From how far away can you see the tops of various objects?
| Object | Object Height (m) | Visable Distance (m) | Vis. Dist. (miles) |
|---|---|---|---|
| The Ground Itself | 0 | 4,800 | 3.0 |
| Garden Gnome | 0.5 | 7,300 | 4.5 |
| Another Person | 1.8 | 9600 | 6.0 |
| A Male Giraffe | 5.2 | 13,000 | 8.0 |
| An Aspen Tree | 16 | 19,000 | 12 |
| Statue of Liberty (with base) | 93 | 39,000 | 24 |
| Great Pyramid of Giza | 140 | 47,000 | 29 |
| Statue of Unity (with base) | 240 | 60,000 | 37 |
| Burj Khalifa | 830 | 110,000 | 67 |
| Mount Everest | 8800 | 340,000 | 210 |
| Severe Thunderstorm | 18000 | 480,000 | 300 |
Arc distance along the ground is same as straight-line distance, up to the precision I used for these numbers. Once you get up to the Mount Everest row, the difference is on the order of one mile.
The practical takeaways for hexcrawling are that if you're standing in the middle of a flat twelve-mile hex, then:
- You can just barely see the top of someone's head if they're standing at the edge of the hex. (But there's probably a shrubbery in the way.)
- You can see the top of a mature tree standing in the middle of the neighboring hex. (If you use a telescope and there are no other trees in the way.)
- You can see the top of a giant robot from two hexes away. (Very important to know.)
- You can see storms and mountains from quite some distance. (Haze will be more important than horizon by that point. I don't know whether you'd actually be able to recognize a storm at 300 miles (25 hexes), but here are a couple anecdotes of people noticing thunderstorms from more than 120 miles (10 hexes) away under the right conditions.)
I've seen similar numbers before, but wanted to recalculate everything in a tidy little list for my own use.
Calculator widget below



