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Idea of the Telescope
In the Netherlands, Hans Lippershey discovers that holding two lenses up some distance apart bring objects closer. He applies for a patent on his invention. This is the first documented creation of a telescope. The idea is independently developed by Jacub Metius and Sacharias Janssen. The patent to Lippershey is denied. -
First Drawing Through Telescope (July 26th)
Thomas Harriot, an English astronomer, mathematician, ethnographer, and translator becomes the first person to make a drawing of the Moon through a telescope over four months before Galileo. -
Telescopes Developed for Astronomical Observation
Galileo, after simply hearing that the device was invented, builds several telescopes of his own and turns them toward the heavens. He dared to publish his findings and was nearly burned at the stake for it. There are other earlier recorded astronomical uses including viewing stars with Lippershey's own first telescope during its demonstration and Thomas Harriot's views of the moon not long after. He discovered four satellites of Jupiter and resolved nebular patches into stars. -
Invention of the Reflecting Telescope
Newton produces the first successful reflecting telescope, using a two-inch diameter concave spherical mirror, a flat, angled secondary mirror, and a convex eyepiece lens. The reflector telescope designed opened the door to magnifying objects millions of times. It was made of copper and tin (Speculum). It would tarnish quickly and need re-polishing at least twice a year. Newton believed that only mirrors would eliminate chromatic aberration and that it could never be done with lenses. -
Proposition of Convex Secondary Mirror
Cassegrain proposed a similar design using a convex secondary mirror that allowed the tube to be shortened even more. More importantly, it cancelled aberrations from the primary mirror and would have resulted in much sharper images, had opticians been able to produce quality mirrors. It is interesting that Gregory, Cassegrain, and later Newton were able to invent designs that were so far ahead of their time that no one could actually make one. -
Development of the Reflector Telescope
Lord Rosse constructed in Ireland a reflector with a 185-cm mirror and a focal length of about 16 metres. This was used to explore thousands of nebulae and star clusters. Lassell built several reflectors. His telescope had greater reflecting power than Rosse’s, and it enabled him to catalogue 600 new nebulae as well as to discover several satellites of the outer planets, Triton (Neptune’s largest moon), Hyperion (Saturn’s 8th moon), and Ariel and Umbriel (2 of Uranus’s moons). -
Hubble Telescope (April 25th)
Work began on a telescope in 1970 that was to become the Hubble Space telescope, named after American astrologist Edwin Hubble. It was deployed to its position beyond the earth's atmosphere where it now orbits the planet. From this position it is able to give a view of the universe free from distortion. Its use has led to many significant discoveries, such as the age of the universe, the identity of quasars and the existence of dark energy.
