Lookum Observatory

Munising, Mi.                   

History of the Telescope            









Galileo's 43mm - 9X Refractor Galileo Galilei's Telescope
Though not the first telescope maker, in 1609 Galileo was the first to make major astronomical discoveries with it. He found the moon had craters, the sun had spots, and four moons orbited Jupiter. When he discovered Venus to have phases, he became a public defender of Copernicus' heliocentism (sun centered system). Not bad for 1.75" - 9X & 24X refractors.


Hevelius' 60' refractor Hevelius' 60' Refractor
To reduce the effects of chromatic aberrations inherent in a single lens objective, telescope makers made refractors of longer and longer focal lengths. In 1673 Johannes Hevelius constructed several, the longest being an unimaginable 140' in length.


Isaac Newton's Reflector Isaac Newton's Reflector
Concluding that refractors would always be plagued by chromatic aberration, in 1672 Isaac Newton went to work on constructing a reflecting telescope. Implementing the design of frenchman Descartes, he developed a system that used a 1.5" - 40X spherical mirror objective and a small secondary flat mirror set at 45 degrees, to reflect light to an eyepiece at right angle to the optical axis; the Newtonian reflector was born.


                                    Herschel's 40' Reflector Herschel's 40' Reflector
Having already discovered Uranus with his 6.25" reflector in 1781, William Herschel went on to build a 12" and an 18.8". Yet determination to build an even larger instrument, led to this 48" x 40' f.l. monster with which he discovered the 6th and 7th satellites of Saturn.


Fraunhofer 9.5 inch Achromat Fraunhofer 9.5" Achromat
Improving on the design of the achromatic refractor, in 1824 Joseph Fraunhoefer calculated more accurately than ever before the lens curvatures of the two elements making up the achromatic doublet objective. From those calculations came this 9.5" x 14' fl. masterpiece, which was the largest in use and became the design standard for other instruments of that time.


Alvan Clark 18.5" Clark 18.5 inch Refractor
The drive for larger aperture reached 18.5" in 1866 when the firm of Alvan Clark constructed a refractor for the Chicago Astronomical Society. The scope was made famous even before it was completed; during the testing of the lens Clark's son discovered a companion to the star Sirius.


                                                        Lowell 24" Lowell Observatory 24 inch
Another Alvan Clark telescope was key to the work of Percival Lowell from 1894 onward as he pursued the study of canals on the surface of Mars at Lowell Observatory in Flagstaff, Arizona. Though his observations were disputed and later proved wrong, Lowell focused attention on planetary astronomy.


Lick 36" Lick Observatory 36 inch
The era of the big refractors was well under way when the Lick Observatory opened it's doors on June 1, 1888. It soon became the leading center for the study of radial velocities of stars and nebula, using the largest refractor in the world - the Clark 36".


                                                 Yerkes 40" Yerkes Observatory 40 inch
When George Ellery Hale persuaded Charles T. Yerkes to provide funds to build a 40" refractor and the Yerkes Observatory to house it, he used the arguement that it would "lick the Lick". In 1897 when completed by the firms of Alvan G.Clark and Warner & Swasey, it did and remains to this day the largest refractor in the world. The refractor had reached its limit.


Mount Wilson Observatory 60inch Mount Wilson 60"
Unsatisfied with the results he was getting with the 40" refractor and the Wisconsin skies for his high-dispersion spectroscopy, Hale used a mirror purchased for him by his father in 1894 and figured by George Willis Ritchey to convince the Carnegie Institute of Washington to finance a 60" reflector at a new observatory on Mount Wilson in 1908.


McDonald 82" McDonald Observatory 82 inch
Even before becoming director of Yerkes Observatory in 1932, Otto Struve realized that for Yerkes Observatory to survive, a new telescope at a better western site was essential. Building on efforts by former director Frost, he brought about an agreement between the Yerkes and the University of Texas to build an 82" reflector at the new McDonald Observatory in west Texas mountains. It saw first light in 1939 and he is credited by some with saving the Yerkes observatory.


               Mount Wilson 100" "Hooker" Mount Wilson Observatory 100 inch
While the 60" was still under going tests, Hale convinced J.D. Hooker to finance the building of a 100" reflector. George Ritchey once again directed the figuring and the telescope saw first light in 1917. With two powerful instruments, Mount Wilson Observatory soon became a major astrophysical research center. It was with the "Hooker" that Edwin Hubble measured the distances to several large "spiral nebula" and ended a long debate by showing that they were actually galaxies; external to the Milky Way.


Mount Palomar Observatory 200 inch Mt. Palomar 200"
Hale once again pushed for a still larger reflector. He was successful in convincing the Rockefeller Foundation and the California Institute of Technology to enter into a joint venture in building a 200" reflector and an observatory to house it, on Mount Palomar. Though Hale died before it's completion in 1948, the 200", which bears his name was the largest and most prolific for the next three decades.






References used:
Yerkes Observatory, 1892-1950; Donald E. Osterbrock
History Of Astronomy, An Encyclopedia; John Lankford
The Flammarion Book Of Astronmy; Simon & Schuster
The Picture History Of Astronomy; Patrick Moore

Questions or comments welcomed by P.J. Anway at: Email

(Images and text may be used with written permission of the author)


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