It's hard to tell who invented the telescope first. It is known that ancient people used magnifying glasses. The legend has also come to us that Julius Caesar allegedly looked at the foggy British soil in a telescope during a raid on Britain from the shores of Gaul. Roger Bacon, one of the most remarkable scientists and thinkers of the XIII century, he invented such a combination of lenses, with the help of which distant objects seem to be close to each other when looking at them.
History of the first optical observations
It is unknown whether it was true or not. However, it is undisputed that at the very beginning of the XVII century in the Netherlands three opticians - Lippersgey, Mezius, and Jansen - almost simultaneously announced the invention of the telescope. It is said that as if the children of one of the opticians, playing with lenses, accidentally placed two of them so that the distant bell tower suddenly seemed close. However, by the end of 1608, the first telescopes were made and rumors of these new optical instruments spread rapidly across Europe.
Galileo Galilei
In Padua, Galileo Galilei, a professor at the local university, was already a well-known figure, an eloquent speaker and a passionate supporter of Copernicus' teachings. When he heard of the new optical instrument, he decided to build his own telescope. He himself tells of this as follows: "Ten months ago, it became known that a Flemish man built a perspective by which visible objects, far from the eyes, are clearly distinguishable as if they are close. This was the reason why I turned to finding the basis and means to invent a similar tool. Shortly afterward, based on the doctrine of refraction, I grasped the essence of the case and first made a lead pipe, on the ends of which I placed two optical glasses, both flat on the one hand, on the other hand one convex-spherical glass, the other concave.
This first-born telescopic technician was only tripling in size. Later, Galileo managed to build a more advanced tool, which increased by 30 times. And then, as Galileo writes, "having left earthly affairs, I turned to heaven.
In dark transparent nights, the telescope could see many stars in the field of view that were inaccessible to the naked eye. Some of the fog spots in the night sky turned out to be clusters of poorly lit stars.
The first discoveries
The Milky Way, a whitish, slightly luminous band that surrounded the sky, was also a great gathering of stars.
The imperfection of the first telescope prevented Galileo from seeing Saturn's rings. Instead of the rings, he saw two strange appendages on Saturn's side.
Galileo's discoveries marked the beginning of telescopic astronomy. But his telescopes, which confirmed the new worldview, were not perfect.
Galileo discovered mountains and mountain ranges on the Moon, as well as several dark spots he called the sea. At the first acquaintance with the surface of the Moon of Galileo it was evident that the surface of the Moon seemed to be similar to the surface of the Earth - on the lunar surface (as well as on the Earth's surface) there were large mountains, and mountain ranges, and the sea, and valleys. At first, Galileo assumed the presence of water (in the seas) and the atmosphere on the Moon.
Galileo's remark on the nature of the Moon and on the lunar mountains and mountain chains and his measurements of the heights of the lunar mountains show that he was on the point of view of Copernicus and Bruno. From the reading of the Starry Herald, readers could only deduce such a conclusion that Galileo, on the basis of his telescopic observations, considers the Moon to be similar in nature to the Earth.
When creating telescopes since Galileo, the following rule is followed: the telescope's output pupil should not exceed the observer's pupil. It is easy to see that, otherwise, some of the light collected by the lens will be lost in vain. A very important value characterizing the telescope lens is its relative opening, i.e. the ratio of the telescope lens diameter to its focal length. The luminous intensity of the lens is the square of the telescope's relative opening. The "lighter" the telescope, i.e. the more luminous its lens is, the brighter the images it produces. The amount of light collected by the telescope depends only on the diameter of its lens (but not on the aperture ratio). Because of the phenomenon called diffraction in optics, the bright stars appear to be small discs surrounded by several concentric iris rings when viewed through telescopes. Of course, diffraction discs have nothing to do with real star discs.
Such was the modest beginning of the later "Championship" of telescopes - a long struggle for the improvement of these main astronomical instruments.