Information on Mirror Telescopes

Mirrored telescopes can be made using either glass mirror or liquid mirror. Liquid mirror is made of a reflective liquid, usually mercury. Liquid mirror is lightweight so is much cheaper to manufacture and a telescope only needs a small amount of mercury. One negative to a telescope made of liquid mirror is that it must only point up. It cannot be tilted or it will lose its shape. Some scientists are working with an anti-freeze type substance with small amounts of iron in it. By using electromagnets, they have been able to move the mirror substance so it can look in different directions.

In 1976, Russian astronomers created the largest telescope in the world. However, they were unable to get accurate images because the glass in the mirror would sag under its own weight. They knew then that if they wanted larger images, they would have to find another way than the glass they were using. They tried using many mirrors that would work together to create a single image. These telescopes were called multiple mirror telescopes and were controlled by computers. Scientists then started working on another change in telescopes where they spun molten glass in a mold to create the final shape of the mirror.

The objective mirror for a telescope is the easiest to make. It is concave and is adequate for small and medium sized telescopes but cannot probe deeply enough to provide much information about outer space. The substances used for reflection in telescopes will continue to be tested and new ones will be developed as people choose to explore outer space.