## Artificial Horizon and Earth’s Curvature

An artificial horizon, or attitude indicator, is a flight instrument that indicates the aircraft’s orientation relative to Earth’s horizon and gives an immediate indication of the smallest change of orientation. An artificial horizon utilizes a gyroscope to detect the change of orientation and pendulous vanes to continuously correct the orientation relative to the level.

Flat-Earthers claim that an artificial horizon should drift over time if the airplane is flying over the spherical Earth because the gyroscope will eventually drift and no longer points toward Earth’s center. In reality, an artificial horizon has a self-correcting mechanism, keeping the gyroscope upright if it is displaced for any reason, including by the aircraft’s motion following Earth’s curvature.

## Foucault Gyroscope

In 1851, Léon Foucault used a pendulum to demonstrate the rotation of the Earth. Despite his success, he was not fully satisfied with the pendulum experiment because of the dependency on the sine of latitude, which the public found difficult to understand. He later designed a device which he named ‘gyroscope.’

A spinning gyroscope keeps a constant axis of rotation in space, so it should slowly rotate with respect to an observer attached to the rotating Earth. The challenge was technical; it would need to have minimal friction, and it has to be able to spin for a sufficient duration so that the precession due to Earth’s rotation can be observed.

## “Behind the Curve”: the Ring Laser Gyroscope Experiment

“Behind the Curve” is a documentary showing behind the scenes on what is happening in the flat-Earth community in the United States just before a flat-Earth conference. In a section, the film shows us how a flat-Earther did an experiment involving a ring laser gyroscope, which proved the very thing he tried to disprove: Earth’s rotation; and that he was unwilling to accept the result.

## The Aether Experiments are Never Evidence of Flat and Stationary Earth

Aether was the hypothetical material that fills the region of space. It was assumed to be the medium that allows light and gravity to propagate in space. Throughout the late 1800s and early 1900s, some experiments were carried out to prove if the aether exists.

Flat-Earthers (and geocentrists alike) often use the results of these experiments to support their case that the Earth is stationary. But they are wrong. These experiments were conducted to prove if the Aether theory, or if one of its competing hypotheses —like the Special Relativity— better explains reality.