Watching the Stars

Do you remember lying on the lawn at night as a youngster, gazing up at the stars and wondering what they were like? There is now a way to bring those distant objects closer. You can view them through a telescope. The reflecting or mirror telescope was developed to search the heavens. It uses a concave mirror at the bottom end of the telescope to collect the light, which it directs to the focal point at the center of the mirror. This captured image allows the viewer to see the object of interest with a much closer perspective. This method reduces the distortion of the viewed object. The support structure is on the outside of the telescope, allowing for larger mirrors and increased visibility. Of course there became noticeable disadvantage as the size of the telescopes grew larger, such as the ability to store and relocate the telescope and the need for adjustments to obtain the optimum light reflection.

In the mid 1900, the largest telescope was the Hale telescope, measuring 200 inches in diameter. The Russians developed a telescope with a single mirror at 236 inches in 1976, but it proved to sag and give distorted images. In order to overcome the limitations of the single mirror telescope, a multiple mirror telescope was developed. The first was a six mirror telescope built in Arizona. The total diameter was approximately 4.5 metes. There were some difficulties in the ability to get the six mirrors to focus on exactly the same spot at the same time. Since then the magnitude has increased. The SALT telescope in South Africa measures approximately 11m in diameter. The multiple mirrors on this telescope look like a honeycomb and each mirror is controlled by computer.

The newest phase of telescope is the liquid mirror telescope.