Lunar Distance by Parallax

Use your observations of the solar eclipse to estimate the distance from earth to the moon.

The most direct way to determine the distance to astronomical objects is to measure their parallax. This is the angle, in degrees, that the object appears to shift in the sky from position A to B as you view it from two different vantage points (1 and 2). The separation between these vantage points, 2R in kilometers, is related to this parallax angle q by the distance to the object D as the diagram below shows.

Lunar Distance by Parallax PDF download button

Thumbnail Image Credit: Sten Odenwald NASA/HEC