Telescopes have allowed us to bring what is far and mysterious up close and personal. Scientists and astronomers have built telescopes for a variety of uses, whether it’s for imaging, spectroscopy, or time monitoring. Within the realm of telescopes, there a two main types: refracting and reflecting telescopes. Between the two types, reflectors are the type mainly used in current astronomical research.
Reflecting telescopes use two mirrors to reflect the light coming in into a focus. The primary mirror, which gathers the light, reflects it onto a secondary mirror that lies somewhere in front of it. This secondary mirror then focuses the light into one spot, where a recording device, such as our eyes or some type of instrument, takes it in. There are three main variations of reflecting telescopes: Cassegrain, Newtonian, and Nasmyth focus. These variations differ in the where the light is ultimately focused as well as the possession of a third mirror within the Nasmyth-focus type. Reflecting telescopes are primarily used in astronomy due to being more practical and easier to construct. While refracting telescopes required two high-quality lenses, reflecting telescopes need only one. Reflecting telescopes also placed most of its weight at the bottom, making it far easier to stabilize than refracting telescopes. Throughout history, reflecting telescopes have helped astronomers discover new star systems and further examine ones we known, helping us broaden our knowledge of the universe as a whole.
Jeff's Astro Blog 