Lookout Mtn. Professional Guide
Detailed Trail Description from our Guidebook
"Lookout Mtn., a seemingly minor bump on the south ridge of Mt. Baldy, plays an important role in the history of science. In 1915, a fire lookout was constructed on the summit to take advantage of the commanding views. In 1926, Albert Michelson conducted a groundbreaking experiment here to measure the speed of light. He placed a prism on Mt. Wilson and a large mirror on Lookout Mtn. The United States Geodetic Survey team surveyed the distance between the two peaks with unprecedented accuracy. By bouncing a beam of light from the prism off the mirror and carefully measuring the round trip travel time, he determined that the speed of light is nearly 300,000 kilometers per second or about 670 million miles per hour. In 1927, a windstorm destroyed the fire lookout and now all that remains are some concrete pilings."