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This post starts my series of posts related to telescopes. In this first post I talk about the history of telescopes and some basics of their mechanism.

The first time human beings watched the sky was before 1600 tales. There were no artificial equipment for skywatching, just eyes. A telescope was invented in the beginning of 1600 tales. Galileo Galilei used a telescope since 1609. Later in the end of 1600 tales Isaac Newton developed a mirror telescope. In the end of 1800 photographing equipment were connected with telescopes, which started a new era in astronomy. Various technological innovations were born in the beginning of 1900, but the real growth of astronomy started in the end of 1960 because of computer aided systems.

Our plane’s atmosphere causes headache for astronomers because it filters out most of the radiation from the space. The problem is that only a fraction of the electromagnetic radiation gets through the atmosphere. Only visible light (vawelength 300-800 nm) and radiovawes (1 mm – 15 m) can be detected down on Earth. Additional problems are caused by refraction and scintillation. These phenomena can be seen when using a telescope, a star looks like a “disk”. The mentioned phenomena in the atmosphere forces us selecting carefully the locations for telescopes. The best places for observatories on our planet are in Chile, Hawaii and the Canary Islands.

There are two types of optical telescopes, namely refractors (dioptrics) and reflectors (catoptrics). Refractors use lenses whereas reflectors use mirrors. The basic idea of a optical telescope is to gather and focus light mainly from the visible part of the electromagnetic spectrum. Refractors behave much as camera objectives, whereas reflectors create the image in the focal point of the telescope. There are various combinations and configurations of the telescopes, such as Newton and Cassegrain telescopes.

The first astronomical images were taken somewhere late 1800. Nowadays CCD (Charged-Coupled Device) cameras which provide many times better images than those regular cameras.

Here are few big telescopes around the world.

- Mauna Kea
- Gemini

- Harlan J. Smith