Astronomical telescope is the main tool for observing celestial bodies and capturing celestial information. Telescopes have been developing continuously since Galileo made the first telescope in 1609. From the optical band to the full band, from the ground to the space, the observation ability of the telescope is getting stronger and stronger, and more and more celestial information can be captured. Humans have telescopes in electromagnetic waves, gravitational waves, cosmic rays and so on.
Telescopes originated from glasses. About 700 years ago, people began to use glasses. Around AD 1300, Italians began to make convex lens reading glasses. Around 1450, nearsighted glasses also appeared. 1608, an apprentice of Hans Ripahi, a Dutch glasses manufacturer, happened to find that you can see things in the distance by stacking two lenses together.
1609, after Italian scientist Galileo heard about this invention, he immediately made his own telescope and used it to observe the stars. Since then, the first astronomical telescope was born. Galileo observed sunspots, lunar craters, Jupiter satellites (Galileo's satellites) and Venus through telescopes, which strongly supported Copernicus' Heliocentrism.
Galileo's telescope is made by using the refraction principle of light, so it is called a refracting mirror. 1663, Scottish astronomer Gregory made a Gregory mirror based on the principle of light reflection, but it was not popularized because of the immature manufacturing process. 1667, British scientist Newton slightly improved Gregory's idea and made a Newton-style mirror with a diameter of only 2.5 cm.
But the magnification is more than 30 times, and the chromatic aberration of the refractive telescope is eliminated, which is very practical. 1672, seglin, a Frenchman, used concave mirror and convex mirror to design the card seglin reflector, which is the most commonly used one now. This kind of telescope has long focal length, short mirror body, large magnification and clear imaging.