Frequently asked questions

The Carnegie Institution of Washington (CIW) founded Mount Wilson Solar Observatory in 1904 and still owns it. The astronomers of CIW decided that they would prefer to focus their efforts on deep-sky astronomy research for which Mount Wilson's sister observatory, Las Campanas Observatory near La Serena, Chile, is better suited. CIW thus decided to look for a partner to operate Mount Wilson Observatory independently. The Mount Wilson Institute was founded in 1985 for this purpose. In the meantime, in order to save funds needed at their southern hemisphere observatory, CIW took the Hooker 100-inch telescope out of operation in 1986. The telescope was never meant to be closed down permanently and it was maintained in a condition consistent with its expected return to service. In 1992, under the auspices of the Mount Wilson Institute, the 100-inch saw "second light" in a ceremony similar to the "first light" observances held when new telescopes are commissioned. The news stories reporting the closing of the 100-inch telescope are largely responsible for the public misconception that Mount Wilson Observatory shut down operations altogether.

When the Mount Wilson Solar Observatory (as it was known until 1917) was founded by CIW, solar astronomy was the focus of the observatory's research efforts. The Snow, 60-foot tower and 150-foot tower telescopes were built between 1905 and 1912 in order to study our closest star. The 60-foot and 150-foot tower telescopes are still used for solar research today, now under the operation of the University of Southern California and the University of California, Los Angeles, respectively. The Snow telescope is now used primarily for the CUREA educational program.

Along with the earlier telescopes built during the era of founder George Ellery Hale, new telescope systems have been built on Mount Wilson since 1988. The Infrared Stellar Interferometer of the University of California, Berkeley combines the light of three 72-inch telescopes to detect very fine detail on cool stars and other objects in space. The CHARA array, consisting of six 40-inch telescopes widely space on the mountaintop has just been completed. When fully operational, it will be the largest optical interferometer ever built. Mount Wilson is not only still in operation but continues the tradition begun almost 100 years ago of new technologies and instruments on the cutting edge of astronomical research.