The Hobby–Eberly Telescope
The HET has massive mirror which remains stationary, while the other components maneuver across it.
The telescope can watch a single object for about two hours continuously.
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such as visible light).
A telescope used to observe astronomical objects such as stars, planets etc. is called an astronomical telescope. Telescopes
are of two types:
(1) Reflecting Telescope
(2) Refracting Telescope.
(1) Reflecting Telescopes : This type of telescopes uses a combination of concave mirrors and lenses. Since
reflecting telescopes use mirrors, the design is sometimes referred to as a "catoptric" telescope.
(2) Refracting Telescopes : A simple refracting telescope essentially consists of two convex
lenses. One of the lenses – called the objective, has a large focal length and large diameter. It is fitted at the end
of a tube. The other lens called the eyepiece has a short focal length and a small diameter. It is fixed at the end of another
tube.
A telescope which is used to see the details of the distant objects on the earth is called a terrestrial telescope. A terrestrial telescope gives erect images of the objects. In a terrestrial telescope, one more lens or reflector (prism) is inserted between the objective and the eye piece which reverses the inverted image.