Ole Christensen RoemerThe speed of light measured by using the moons of Jupiter
In 1676, Roemer’s greatest contribution was establishing the first relatively accurate measurement of the speed of light. His studies of Jupiter’s moon lo and its eclipses helped him predict the periodicity of an eclipse period for the moon. Several months later, his predications were becoming less accurate by the long intervals of time, concluding in the result of 22 minutes. But over a several month period, his predications became more accurate again by the cycle repeating itself. Roemer observed that the disparities were made by the differences in the distance between Earth and Jupiter caused by the orbital movement of planets. When Jupiter moved away from Earth, light had a longer distance to travel, which took additional time to reach Earth. Roemer applied the relatively inaccurate calculations for the distances between Earth and Jupiter and soon was able to figure out the approximation of the speed of light, which was 137, 000 miles per second.
Here is Roemer's drawing of lo's Jupiter Eclipse
Back to homepage |
