Optical telescopes are the most recognizable, as they are very similar to those you use in your own backyard. Optical astronomy provides both the most breath-taking images we see and the most basic information we know about our solar system, the Milky Way, and all the galaxies surrounding us.

Photo: The Clark Telescope at Lowell Observatory

Optical astronomy is limited by both the relative narrowness of the optical spectrum and the fact that the Earth's own atmosphere blocks out and bounces around some of this light, distorting the image we see. The human presence is also a problem for optical observing, as light pollution also severely limits the quality of data you can collect. Because of this, observatories are usually located in places with a low percentage of daily cloud cover (less clouds = more observing), away from towns and city (less light pollution = better observing), and normally at high altitudes (less atmosphere = less scattering).

Given these limitations, space-based observatories (such as Hubble) give clearer images, and better quality information about the objects. However, putting a telescope in space is a difficult, time consuming and very costly practice. As such, a lot of advancements in the field of optical astronomy have been focused on terrestrial based observatories^.[1]