Speed of light and Moon distance from an occultation of Mars by the Moon
arxiv.org
arxiv.org
(The precision-metrology part of me feels compelled to point out that any absolute measurement of the speed of light using this method should include an estimation of the covariance of the result (and its uncertainties) with the variation of the assumed value of c used by GPS for timing and position determination).
There's enough distance between us and the Moon that if you had a flashlight bright enough, you could easily perceive the delay between switching it on and seeing the Moon's surface brighten, as the light made the return trip. Something to think about next time you look up at the Moon and wonder about its scale and distance.