[adsfqwop]

Researching flat earth and flat earthers forced me learn a lot about how we can prove globe earth in various interesting ways.

One cool device I discovered is the Gyrotheodolite. It's a north-seeking gyrocompass, used in mining where GPS is not available and a magnetic compass would be too inaccurate.

The north-seeking effect happens only because the earth is round and rotates the way it does. Without this rotation, the gyrocompass would not work. Hence the earth is round and it rotates. QED.

https://en.wikipedia.org/wiki/Gyrotheodolite

[Karellen]

I think an equatorial mount/platform is one of the best devices for demonstrating it.

It's possible to cobble a simple one together out of pretty basic parts, or even scrap. It's just a turntable set at an angle, which you can mount some kind of pointer/viewfinder/camera on.

The demonstration comes in that it has to be set up so that the axis of the turntable is at an angle to the ground equal to your latitude (at 0°lat it has to be horizontal, at 90°lat vertical), and the direction of the tilt is towards a pole (north in the northern hemisphere, south in the southern). You can then fix your webcam or whatever to the turntable, pointing at any celestial object (star, moon, sun - but don't look directly at the sun!) and see that you can follow any of them at a constant rate of approx 15° per hour, for days. You can follow when and where the object goes below the horizon, and predict when and where it will rise above the horizon again.

All of those requirements, from the tilt angle being equal to your latitude, to the requirement to point the tilt north/south, to the constant rate of rotation, and the direction of rotation depending on whether you're in the north or south hemisphere, are easily explained by the shape of the earth, and make no sense in any flat earth model. And they're easily checked. You might need a few collaborators to check the results at different latitudes, but there seem to be plenty of flat earthers out there.

Also the slightly different rotational speeds needed to track the sun (~1°/day) and the moon (~4°/day) vs that of all of the stars also follow from the heliocentric model of the solar system, and not whatever alternate bonkers cosmology someone has pulled out of their ass.

https://en.wikipedia.org/wiki/Equatorial_mount

https://en.wikipedia.org/wiki/Equatorial_platform

[scotty79]

I learned about pendulous vanes from videos debunking flat earthers.