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Telescope


Telescope
Like points, the telescope has been created by man, far from science. Descartes in his "Dioptrics" so the story of this important invention: "To the shame of the history of our science is so wonderful invention was first done purely empirically and, moreover, thanks to the occasion. About thirty years ago, Jacob Metsius, "a person never studied science," fell in love to arrange mirrors and incendiary glass, having to do with different lens shapes, even think to look through a combination of convex and concave glass, and then so well set them on the two ends of the tube that unexpectedly won the first telescope. " They say that it pushed his children playing with glass.

Thus, the first telescope appeared in the Netherlands in the early XVII century. And it was invented, except Metsiusa, independently of each other several people. They were not scientists-optics, and ordinary craftsmen. One of them - the spectacled wizard from Middelburg John Leppersgey - introduced in 1608 he created a tube-General States. Hearing about this new product, the famous Italian scientist Galileo Galilei wrote in 1610: "Ten months ago, has reached our ears that a Belgian constructed perspective (as Galileo called the telescope), by means of which visible objects, far situated from the eyes become clearly distinguishable, as if they were close. " Principle of operation of the telescope, Galileo did not know, but he was well versed in the laws of optics and soon realized his device and he constructed a telescope. "At first I made a lead pipe, - he wrote - at the ends of which I placed two glasses of glass, both flat on one side, on the other hand was one of a convex-spherical, the other concave. By placing the eye to the concave glass, I saw things big enough and close. Namely, they appeared close to three times and ten times larger than when considering the natural eye. After that, I developed a more accurate tube, which represented an increase of more items than sixty times. For this, sparing no effort and no money, I have reached that built himself a body so perfect that things seemed to be looking through it a thousand times larger and over thirty times approximate than when considering using natural abilities. " Galileo was the first to realize that the quality of the lens manufacturing for glasses and telescopes should be quite different. Of the ten points, only one old enough to use the telescope. He perfected the manufacture of lens technology to such an extent as it has never reached. This allowed him to make a pipe with a thirtyfold increase, while telescopes eyeglass craftsmen increased only three times.

Galilean telescope consists of two panes of which addressed the subject (the lens) were convex, that is, collecting the light rays, and addressed to the eye (ocular) - concave, scattering glass. The rays coming from the object is refracted through the lens, but before giving the image, they fell to the eyepiece, which they scattered. With this arrangement, the glass-rays did not do the actual image, it is made already by the eye, which was here as if the optical part of the pipe itself.

Lens O gave in its focus ba real image of the observed object (the image is opposite of what one would see if taking it on the screen). However, a concave eyepiece O1, installed between the lens and the image dissipated rays coming from the lens, do not give them the cross and prevent the formation of a valid ba image. The diverging lens formed imaginary image of the object in the A1 and B1 points, which was at a distance of best vision. As a result, Galileo received a sham, increased direct image of the object. The increase equal to the ratio of the telescope focal length of the lens to the focal length of the eyepiece. It would seem possible to obtain arbitrarily large increase. However, the strong increase in the limit laid the technical possibilities: it is very difficult to polish a large diameter glass. Furthermore, too large for the focal lengths required excessively long tube, which was impossible to work. The study of Galileo's telescopes, which are kept in the museum of the History of Science in Florence, shows that his first telescope gave an increase of 14 times, the second - in 19, 5 times, and the third - 34, 6 times.

Despite the fact that Galileo can not be considered the inventor of the telescope, it certainly was the first one who created it on a scientific basis, using the knowledge which were known to the optics of the beginning of XVII century, and turned it into a powerful tool for research. He was the first person who have looked at the night sky through a telescope. So he saw that before him have not seen anybody. First of all, Galileo tried to see the moon. On its surface were the mountains and valleys. The mountains and circuses silver in the sun and long shadows loomed in the valleys. Measure the length of the shadows enabled Galileo to calculate the height of lunar mountains. In the night sky, he discovered many new stars. For example, in the constellation Pleiades turned over 30 stars, while there were only seven first. In the constellation of Orion - 80 instead of 8. The Milky Way, which is regarded as the earlier glowing pair crumbled in the telescope on the enormous number of individual stars. To the great surprise of the Galilean telescope Star seemed smaller than when viewed with the naked eye, as they have lost their halos. But the world presented by tiny discs, like the moon. Pointing the telescope at Jupiter, Galileo saw four small lights moving in space with the planet and altering its position relative to it. Two months of observations, Galileo guessed it - the moons of Jupiter, and suggested that Jupiter their size many times larger than the Earth. Considering Venus, Galileo discovered that she has phases like the moon, and therefore must orbit the Sun. Finally, watching through the glass purple sun, he found his spot on the surface, but their movement has established that the Sun rotates on its axis.

All of these amazing discoveries were made by Galileo in a relatively short period of time thanks to the telescope. On contemporaries they produced a stunning impression. It seemed that the veil of secrecy was sleeping with the universe, and it is ready to open before the man his innermost depths. How big was at that time an interest in astronomy, it is evident from the fact that only in Italy, Galileo immediately received an order for one hundred tools of your system. One of the first to appreciate the discoveries of Galileo, another outstanding astronomer of the time, Johannes Kepler. In 1610, Kepler came up with a radically new design of telescope, consisting of two lenticular lenses. The following year, he released a major work "Dioptrics", where the theory was considered in detail telescopes and optical instruments in general. Kepler himself could not assemble the telescope - for this he had neither the means nor the qualified assistants. However, in 1613, the scheme has built his telescope Kepler another astronomer - Scheiner.

Many scientists have begun themselves to build telescopes, and more powerful than that of Galileo. Some increase was achieved one hundred times, and the length of the tube reached 30, 40 or more meters. The record belongs, apparently, astronomer Ozu, who succeeded in 1664 to build a telescope with a magnification of 600 times. In this case the tube length was 98 meters. It is easy to guess about the difficulties that had to endure Ozu, conducting observations with such a clumsy device. In 1672, Isaac Newton was able to partly solve this difficulty, he proposed a new design of telescope (dubbed reflector), in which the lens was concave metallic mirror.

From all this it is clear that the creation of the telescope marked a genuine revolution in science in general and in particular in optics. Precision optics came into science as a new means of understanding the world.

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