Airy's Failure

The experiment called Airy’s Failure was a test conducted by Astronomer Royal Sir George Biddell Airy in 1871, in which Airy failed to detect the motion of the earth. The experiment showed that the stars move relative to a horizontally fixed Earth. By first filling a telescope with water to slow down the speed of light inside, then calculating the tilt necessary to get the starlight directly down the tube, Airy unintentionally demonstrated that the earth was fixed horizontally since the starlight came in at the correct angle without needing to change the tilt of the telescope.

Malcolm Bowden

Malcom Bowden gives an overview of Airy's Failure. Runtime: 6m

Video Description:  “ "Airey's failure" (Reference - Proc. Roy. Soc. London v 20 p 35). Telescopes have to be very slightly tilted to get the starlight going down the axis of the tube because of the earth's "speed around the sun". Airey filled a telescope with water that greatly slowed down the speed of the light inside the telescope and found that he did not have to change the angle of the telescope. This showed that the starlight was already coming in at the correct angle so that no change was needed. This demonstrated that it was the stars moving relative to a stationary earth and not the fast orbiting earth moving relative to the comparatively stationary stars. If it was the telescope moving he would have had to change the angle. ”

Further Reading

• Airy's Failure Reconsidered (Archive) by Walter van der Kamp

See Also

• The Michelson-Morley Experiment
• The Vertical Michelson-Morley Experiments
• Sagnac Experiment
• Aether