Horizontally Challenged

7 Aug 2017


I like views. On our recent holiday we stayed on top of a hill and spent hours looking out at a particularly nice one. From the photographed bit of Tuscany, the furthest point that can be seen directly is about 27km away: a distant hilltop just visible past the shoulder of a closer slope.

I pondered the distance because, just before going on holiday, I had discovered beyond horizons, a website dedicated to photography of very long distances. At the time of writing, the world record is reported to be 443km.

A good bit longer than the view from Villanovia then. More interestingly, 443km is actually further than you can see from the top of Everest, and it’s not even the theoretical straight-line distance. Beyond Horizons has some good explanations of how it’s theoretically and practically possible to see very distant parts of the Earth. Recommended reading!

I dusted off my back-of-the-envelope geometry skills to calculate the distance from the top of Everest to the “sea-level” horizon, just to check that I could (hint: Pythagoras). In the process I discovered Euclidea, a very engaging collection of interactive geometric puzzles. This one came in handy for passing the time on the plane; another recommendation.

And, to finish, another recommendation - and the reason I am pretty sure about the 27km figure in my opening paragraph. This excellent - but slightly technical - “generate a panorama” website. Using global elevation data it will churn out a shaded panorama from anywhere on Earth, labelling prominent peaks and highlighting the furthest directly visible point. Very pleasing, albeit not in the same way as a real view.

Tags: maths, recommendation, geeky