Mount Wilson Observatory

an astronomical observatory on Mount Wilson, near Los Angeles, California, having a 100-in. (254-cm) reflecting telescope.

* * *

Astronomical observatory located atop Mount Wilson, near Pasadena, California, U.S. Founded in 1904 by George Ellery Hale (1868–1938), it was operated jointly with Palomar Observatory as Hale Observatories (1948–80).

Its largest optical telescope, with a diameter of 100 in. (2.5 m), enabled Edwin Hubble and his associates to discover evidence of an expanding universe and to estimate its size.

* * *

  astronomical observatory located atop Mount Wilson, about 10 miles (16 km) northeast of Pasadena, Calif., U.S.

      It was established in 1904 by American astronomer George Ellery Hale (Hale, George Ellery) as a solar-observing station for the Yerkes Observatory, but it soon became an independent observatory funded by the Carnegie Institution of Washington. Hale built a series of ever-larger solar telescopes (telescope) at the summit of Mount Wilson. In 1908 a 60-inch (152-cm) reflector, then the largest in the world, was added for observations of stars (star) and galaxies (galaxy). In the same year, Hale used both his solar telescopes and his laboratory experiments to demonstrate that sunspots (sunspot) were magnetically active regions in the Sun's photosphere. A complementary physics laboratory and suite of administrative and maintenance offices were also built in nearby Pasadena, making Mount Wilson the first stratified observatory complex in the world.

      In 1918 a 100-inch (254-cm) reflecting telescope was put into service. It was not only the most powerful telescope in the world but also a versatile astronomical test bed for new observational techniques. In 1920 the angular diameter of a star was first measured with an interferometer mounted on this telescope, and soon the telescope was being used for astronomical spectroscopy that exploited not only the enormous light-gathering power of the 100-inch mirror but also the innovative subterranean Coudé focus that accommodated a wide range of spectroscopic devices.

      The 100-inch telescope's most important discovery was American astronomer Edwin Hubble (Hubble, Edwin Powell)'s determination of the distance to the Andromeda Nebula (Andromeda Galaxy) 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, building on the work of American astronomer Vesto Slipher (Slipher, Vesto Melvin), Hubble and his assistant Milton Humason demonstrated that galaxies were moving away from one another. This movement is the expansion of the universe. Throughout the 1930s and '40s, Hubble and his associates used the 100-inch reflector to refine the extragalactic distance scale and to probe the large-scale structure of the universe.

      In 1944 the German-born American astronomer Walter Baade successfully resolved the inner regions of the Andromeda Galaxy with the 100-inch reflector and performed photometric studies that showed two populations of stars of different ages and compositions. The difference between the two populations, called Populations I and II, was a critical clue to the evolution of galaxies.

      The 100-inch telescope remained the largest telescope in the world until 1948, when it was surpassed by the Palomar Observatory's 200-inch (504-cm) Hale Telescope, which was designed largely by Mount Wilson staff. Palomar was initially operated jointly by Mount Wilson and the California Institute of Technology, and eventually the two observatories were combined as the Hale Observatories. They are now separate entities, and, although Mount Wilson is still owned by the Carnegie Institution of Washington, it is operated by a consortium known as the Mount Wilson Institute (MWI). MWI has updated the instrumentation, including the 60- and 100-inch reflectors and the solar telescopes. These updates took advantage of the seeing conditions, which are still excellent, and successfully applied adaptive optics and interferometric techniques to problems in solar and stellar astrophysics.

David H. DeVorkin

Additional Reading
There is no coherent full-length history of Mount Wilson Observatory, although episodic studies exist in Helen Wright, Explorer of the Universe (1966, reprinted 1994); and Albert van Helden, “Building Large Telescopes: 1900–1950,” chapter 8 in O. Gingerich (ed.), Astrophysics and Twentieth-Century Astronomy to 1950 (1984).

* * *


Universalium. 2010.

Look at other dictionaries:

  • Mount Wilson Observatory — The 100 inch (2,500 mm) Hooker telescope that Edwin Hubble used to discover the general expansion of the universe …   Wikipedia

  • Mount Wilson Observatory — Observatoire du Mont Wilson Observatoire du mont Wilson Le télescope Hooker de 2,5 m, avec lequel Edwin Hubble fit la plupart des observations ayant c …   Wikipédia en Français

  • Mount Wilson Observatory — an astronomical observatory on Mount Wilson, near Los Angeles, California, having a 100 in. (254 cm) reflecting telescope …   Useful english dictionary

  • Mount Wilson (California) — Mount Wilson The north slope of Mount Wilson as seen from Angeles Crest Highway Elevation 5,712 …   Wikipedia

  • Mount Wilson — can refer to several things: Mount Wilson (California) Mount Wilson Observatory Mount Wilson, New South Wales, a mountain with a small hamlet in Australia One of a list of peaks named Mount Wilson This disambiguation page lists articles about… …   Wikipedia

  • Mount Wilson Toll Road — The Mt Wilson Tollhouse seen along East Altadena Drive at Mendocino Lane. Past this point the road becomes Santa Anita Drive going south toward Pasadena. The Mount Wilson Toll Road (1891 1936) is a historic roadway which ascended Mount Wilson via …   Wikipedia

  • Mount Wilson — Der Hooker Spiegel am Mount Wilson Observatorium Das Mount Wilson Observatorium ist mit einem Alter von 100 Jahren eines der ältesten und erfolgreichsten Observatorien der Erde. Es befindet sich auf dem Mount Wilson auf einer Höhe von… …   Deutsch Wikipedia

  • Mount-Wilson-Observatorium — Der Hooker Spiegel am Mount Wilson Observatorium Das Mount Wilson Observatorium ist mit einem Alter von 100 Jahren eines der ältesten und erfolgreichsten Observatorien der Erde. Es befindet sich auf dem Mount Wilson auf einer Höhe von… …   Deutsch Wikipedia

  • Observatoire du Mount Wilson — Observatoire du Mont Wilson Observatoire du mont Wilson Le télescope Hooker de 2,5 m, avec lequel Edwin Hubble fit la plupart des observations ayant c …   Wikipédia en Français

  • Mount Hubble — (80°52′S 158°19′E / 80.867°S 158.317°E / 80.867; 158.317) is a mountain rising to 2490 m between Mount Field and Mount Dick in the Churchill Mo …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.