History of the Telescope

2127 Words9 Pages
Introduction The telescope is an instrument which increases our ability to observe far away objects through the collection of electromagnetic radiation, the most prevalent type of telescope is the optical telescope which collects light, however there are other kinds of telescopes which collect UV and X -Rays. Optical telescopes use lenses to redirect light to a specified point. Different lenses are used for different magnifications of celestial objects. This essay will be mainly discussing optical telescopes. As we go through the history of optical telescope we can see that there are a few concepts that are fundamental to all the different types of optical telescopes, from the reflecting to the refracting to the hybrid of…show more content…
There are possible solutions to reduce chromatic aberration. The first is the use multiple compensating lenses to nullify the distortion. The second is to use a very long objective focal length, i.e. a large distance between the objective and the focus, to make the effect of chromatic negligible. The second method was actually used by Johannes Hevelius in 1641 to create a 45m focal length telescope (King, 2003). Another disadvantage of the refracting telescope is that the objective lens can only be suppored at the ends and that the glass lens will deform out of shape as it sags under its own weight. Because of these disadvantages, the largest refractor telescope built has an objective of only 1.02 metres across and is located at the Yerkes Observatory. The second largest has a diametre of 0.91 metres, located at the Lick Observatory. The next significant development in the history of optical telescopes occurred in the late 17th Century is the invention of the reflecting telescope. Galileo and others used their understanding of the principles of curved, parabolic mirrors in bringing forth the idea of constructing a telescope with mirrors as a critical element in the formation of images from light sources far away. There have been reports of the construction of reflecting telescopes in the early 1600’s such as one built by Italian professor Niccolò Zucchi,
Open Document