The Michelson stellar interferometer is one of the earliest

astronomical interferometer An astronomical interferometer or telescope array is a set of separate telescopes, mirror segments, or radio telescope antennas that work together as a single telescope to provide higher resolution images of astronomical objects such as stars, n ...

s built and used. The interferometer was proposed by

Albert A. Michelson Albert Abraham Michelson FFRS HFRSE (surname pronunciation anglicized as "Michael-son", December 19, 1852 – May 9, 1931) was a German-born American physicist of Polish/Jewish origin, known for his work on measuring the speed of light and esp ...

in 1890, following a suggestion by Hippolyte Fizeau. The first such interferometer built was at the Mount Wilson observatory, making use of its 100-inch (~250 centimeters) mirror. It was used to make the first-ever measurement of a stellar diameter, by Michelson and Francis G. Pease, when the diameter of

Betelgeuse Betelgeuse is a red supergiant of spectral type M1-2 and one of the largest stars visible to the naked eye. It is usually the tenth-brightest star in the night sky and, after Rigel, the second-brightest in the constellation of O ...

was measured in December 1920. The diameter was found to be 240 million miles (~380 million kilometers), about the size of the

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...

, or about 300 times larger than the Sun.

References

* Michelson, A. A., and Pease, F. G. (1921). ''Astrophys. J.'' 53, 249–259. {{optics-stub Observational astronomy Interferometers

See also

References