An Etymological Dictionary of Astronomy and Astrophysics

An observatory situated on a mountain 1700 m above sea level near Pasadena, California.

It was built in 1904 by American astronomer George Ellery Hale as a solar-observing station for the Yerkes Observatory, but it became an independent observatory funded by the Carnegie Institution of Washington. In 1908 a 60-inch (152-cm) reflector, then the largest in the world, was added for observations of stars and galaxies.

Ten years later a 100-inch (254-cm) reflecting telescope was put into service. It was the most powerful telescope in the world until the construction of the Palomar 200-inch reflector in 1948.

The 100-inch telescope’s most important discovery was Edwin Hubble’s determination of the distance to the Andromeda Nebula in 1924. He showed that the nebula lay beyond the bounds of the Milky Way Galaxy and hence was a galaxy in its own right. Then in 1929, following the work of Vesto Slipher, Hubble and his assistant Milton Humason demonstrated that galaxies were moving away from one another. This movement is the expansion of the Universe.

See also: → mountain; a peak of the San Gabriel Mountains, located in northern Los Angeles County, California, named after Benjamin D. Wilson (1811-1878) a California statesman and politician; → observatory .