Telescope Basics

A telescope is something like a large magnifying glass. It has a series of mirrors (reflecting telescope) or lenses (refracting telescope) which enlarge, focus, brighten, and detail the image. The observer sees more detail than can be seen with just the eye. Telescopes and photograhic equipment also make it possible to make permanent images of stars and so to preserve exact records for study. Before the telescope, all astronomers could observe was position, motion, and brightness. With photographic or electronic detection equipment, fainter objects can be studied in far more detail and with much greater precision.

Telescope history

Many people credit Galileo with inventing the telescope. While he was probably the first person to use a telescope for astronomy, his telescope was not the first built. Significant improvements were made throughout the seventeenth century by Kepler, Newton, and Cassegrain.

During the eighteenth and nineteenth centuries, telescopes for observing visible light got bigger and bigger. Johann Hevelius built one over 150 feet long. Eventually, observatories began being situated at higher altitudes, and in more remote areas.

The twentieth century saw the rise of telescopes for observing in the non-visible range. Radio telescopes came into use in the 1930s, infrared telescopes in the 1970s. The very first space telescopes were also launched in the 1970s.