Why can we see distant objects using a telescope?
A telescope is an optical device used to observe objects at a long distance. It can be said that there are many different opinions about what is related to its original invention. Among the most famous of the inventors was Hans Lippershey, the Dutch eyeglasses dealer in Middelburg. On the one hand, this fast-paced businessman grasped the opportunities very well, applied for the patent of his invention, on the other hand, propagated and persuaded the great political activists to expand the market. Very quickly, a type of telescope called the “Dutch column” has been circulating widely in many European countries.
In May 1609, Galilei – who was teaching at the University of Padua in Venizo, heard this news. He immediately bought many large and small glass panels, burying the research head in the laboratory. In August of that year, Galilei created a telescope that could bring an object closer to 30 times, which would magnify the object by almost a thousand times. He used that telescope to observe the mountains on the Moon’s undulating surface, discovered that Jupiter has four satellites, and also learned that the Milky Way is not a river in the sky. Still, because of infinity, the number of stars constituted. The invention of the telescope brought honor to Galilei and also brought misfortune. Overlooking resulted in his eyes becoming blind later on. The writings based on observations made the Church angry. In the end, he was imprisoned and tasted all the bitterness of the prison.
Galilei’s telescope used a convex lens (objective lens) and a concave lens (eyepiece) to combine with a relatively narrow field of view. The astronomer Kepler, Galilei’s best friend, improved that. The front of the Kepler telescope has a large diameter, a long focal convex lens, called the objective; the back has a convex lens with a small diameter, called the eyepiece. This type of telescope is called a refractive telescope. When light rays coming from a distant scene enter the telescope, converging through the objective into an upside-down miniature real image, it is equivalent to suddenly moving close to the distant scene to where the image is formed. The actual scene, while cleverly, falls into the front focus of the eyepiece. At that time, looking at the eyepiece seems to be holding a magnifying glass and looking at the object, one can see a virtual image enlarged many times. So the distant view, in the telescope, seemed almost narrow.
Newton, the British scientist, opened a different path, invented a kind of reflective telescope, used concave glasses as the objective, the rays reflected through the concave glass again passed through the planar and changed direction, entering the eyepiece, through the eyepiece form the real scene. Because the concave glass is technically allowed to be very large, the more rays of light it can focus on, making the resulting image brighter and brighter. Therefore, it is widely used in astronomical observations. According to statistics, telescopes with a diameter of 1 m or more are reflective telescopes. The Hale telescope located at the Mount Palomar Observatory in California of the United States is the most famous, reaching 5.08 m in diameter; its objective using special glass weighs more than 20 tons and takes seven years just finished. I Heard, lit a candle outside 25 thousand km does not pass that giant eye. On the Caucasus mountains in Russia, one of the largest telescopes today, over 6 m in diameter, can detect extrasolar systems up to 10 billion light-years away.