The field of extrasolar planets is still , in comparison with other astrophysical topics , in its infancy .
There have been about 300 or so extrasolar planets detected and their detection has been accomplished by various different techniques .
Here we present a simple laboratory experiment to show how planets are detected using the transit technique .
Following the simple analysis procedure describe we are able to determine the planetary radius to be 1.27 \pm 0.20 R _ { J } which , within errors agrees with the establish value of 1.32 \pm 0.25 R _ { J } .