Mount Wilson Observatory in Los Angeles 2025

The historic Mount Wilson Observatory is located in Los Angeles County, near Pasadena. Mount Wilson, a peak of 1,740 m (5,710 ft), has a remarkably steady air quality due to the inversion layer that traps smog over the city. This makes it ideal for astronomy and interferometry. In 1926, Nobel prize winner Albert Michelson measured the speed of light, as light beam travelled to a reflecting mirror 22 miles away from the Mount Wilson Observatory. Edwin Hubble also used a telescope mirror over 8 ft wide here and made a few discoveries that helped understand the universe better. In particular, he identified galaxies outside our Milky Way and realized that many of them were getting further from our Earth. Visitors can see the telescope and chair in which Hubble was sitting when he made his observations.

The observatory contains many telescopes of historical value. In part, the 100-inch (2.5 m) Hooker telescope, which was the largest aperture telescope in 1917-1949, and the 60-inch telescope which was the largest in the world in 1908.

The increasing light pollution from Los Angeles is affecting the ability of the Mount Wilson Observatory to do research, but it still remains the center of stellar research.

The observatory is normally open from April till late November. It can be reached by Angel’s Crest Highway or a day-long hike through Angeles National Forest.