Different Types of Telescopes

Summary:

There are different types of telescopes used for various purposes. The terrestrial telescope is a refracting telescope that allows the viewer to observe terrestrial objects through an eyepiece. It consists of three or four lenses arranged so the final image is right side up. On the other hand, the astronomical telescope is used for viewing distant stars and planets. Unlike the terrestrial telescope, the final image in an astronomical telescope is inverted.

Another type is the Newtonian telescope, a reflecting telescope invented by Sir Isaac Newton. It used mirrors instead of lenses to form an image and was developed to overcome the chromatic aberrations present in refracting telescopes.

The Cassegrain telescope is another reflecting telescope used in astronomy. It comprises a large concave paraboloid mirror and a smaller convex hyperboloid mirror. The light is incident on the large mirror and then reflected onto the smaller mirror, which reflects it again to form the final image. The Cassegrain telescope is compact and portable due to its folded optical path.

Reflecting telescopes offer several advantages over refracting telescopes. Mirrors can be made larger than lenses, eliminating the limitations of lens size. They also do not suffer from chromatic or spherical aberration when a parabolic mirror is used. Additionally, reflecting telescopes allow more light to reach the eyepiece as some light gets blocked inside refracting telescopes.

Excerpt:

Different Types of Telescopes

Explain terrestrial telescope
A refracting telescope for viewing terrestrial objects through an eyepiece that consists of three or four lenses so arranged that the final image is right side up.

Astronomical telescope
Astronomical telescopes are used for viewing distant stars and planets the final image in the astronomical telescope is inverted, whereas that in the terrestrial telescope is erect.

Newtonian Telescope
A Newtonian Telescope is a reflecting telescope that uses a combination of mirrors to form an image. It was invented by Sir Isaac Newton as an alternative to the refractive telescope. The primary reason for the invention of the reflecting telescope was to combat the chromatic aberrations in the refractive telescopes.