A. History of different Optical Schemes
1. Spectacles were known in Florence in the late 1200s 2. Dutch spectacle makers made the first 1-lens microscopes, 1595 3. Hans Lippershey (1570-1619) a Dutch spectacle maker, is given credit for inventing telescopes, but he almost certainly was not the first to make one. He let the world know about them. He published his diagrams in 1608. Although at least 3 lens-crafters claimed the creation, his was probably the most sophisticated, with a power of perhaps 10. 4. Telescope introduced to astronomy in 1609 by Galileo. Made his own lenses based on descriptions. Able to get magnifications of about 30, with very narrow field of view. He could only see about ¼ of the Moon's surface at a time. First man to see the craters of the moon, sunspots, 4 large moons of Jupiter, rings of Saturn, phases of Venus. Refractor. Figure is right-side-up and magnified. 5. Kepler improved the design (1611) by replacing the eyepiece. The magnification was higher than Galileo's telescope, but the images are inverted. Christoph Scheiner popularized its use (1630) when he published his work on sunspots. 6. Hevelius (1611-1687, Poland)- huge, long refractors. He and his 2nd wife Elizabetha compiled a detailed star atlas, much like Brahe (published posthumously). Part of a debate with Flamsteed, regarding accuracy of measurements, made with and without a telescope.  7. Huygens- aerial telescope  8.Robert Hooke (1665) published Micrographia, which included his theory of light and color, and his theories of combustion and respiration. At first the "new world" he described met ridicule, but what Galileo did for the telescope Hooke did for the microscope. Fifty-seven illustrations showed the eye of fly, the shape of bee's sting organ, the anatomy of a flea and louse, the honeycomb structure of cork, which he called “cells" because they looked like jail cells.  9.Newton Invented the Reflecting telescope (1672) . MUCH greater light gathering ability, so we can see things 1000s of time fainter than with a refracting telescope. It took decades to work out the problems of the design (tarnishing, ...). 10. William Herschel (1738-1822) Huge reflectors. Hunted comets with the help of his sister, Caroline. Discovered: 2 more moons of Saturn, Uranus, 2 moons of Uranus, double stars really were multiples, infrared radiation, solar system is moving, Milky Way is a disk. Believed that every planet (and sun) was inhabited. 11. Catadiatropic (Catadioptric) Telescope - Bernhard Schmidt (1930) lenses and mirrors 12. Mount Wilson ... Palomar- 20th century workhorses 13. McMath-Pierce Solar Telescope (1962)  14. Arecibo (Puerto Rico 1963) – Largest Radio Telescope  thumb|400px|right|Arecibo Tour 15. SkyLab (1973)- housed first US optical telescope used in space  16. VLA (Socorro, New Mexico 1980) – very large array (of radio telescopes)  17. Keck Telescope (Mauna Kea, Hawaii 1992) -The idea of a segmented mirror dates back to the 19th century. Linking the 2 successfully began in 2001.  18. Hubble (1990)- robotic space telescope, repaired 3 times and still ticking. Original mission was set to end in 2005.  thumb|500px|right|The Final Hubble Upgrade 19. VLT- (1999 Chile) very large telescope, a failed experiment?  20. Chandra X-ray telescope (1999)  and  21. Robert C. Byrd, Green Bank (WV) Radio Telescope 2000 
B. Mounting schemes
1. Ball & socket – (see Netwon's reflector) 2.Alt-azimuth -
Hartness Turret Refractor (1910) Porter's Turret Telescope (VT 1930)
Beaver (PA 1942?)
C. Why do we use telescopes? What can we see? We see the Electromagnetic Spectrum
- 1. Radio – most celestial bodies give off these frequencies. So might civilizations.
- 2. Microwave – communication frequencies used by BEMs.
- 3. Infrared – heat
- 4. Visible
- a. Images to find new objects
- b. Photometry to compare and try to understand variables
- c. Spectroscopy to determine composition and motion
- 5. Ultraviolet – pretty pictures of the sun.
- 6. X-ray – given off by black holes.
- 7. Gamma ray – generally given off in violent bursts by specific stars.
- Telescope Construction