At Uni I was given the hi-tech task of using a straight stick with a tiny disc stuck to it at right angles to measure the ellipticity of the Moon’s orbit. Observations involved pointing the stick at the moon and adjusting the position of the disc so as to cover the Moon precisely. From week to week the disc had to be moved up and down the stick to account for the change in apparent diameter of the Moon as a result of its elliptical orbit…. The same kind of measurement could be performed using a basic digital camera on max zoom. I think we also had a stick with an arc on the end so that we could measure the angular separation between the Moon and bright stars, presumably with the aim of working out other parameters of its orbit (memory is a bit hazy).
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Supporting amateur astronomers since 1890