How was astronomy invented


In 1669, the English physicist Isaac Newton developed the theory of mass attraction. According to this, bodies should exert a gravitation on each other through their mass. In his work "Principia Mathematica" he traces Kepler's laws back to this attraction. The work was the cornerstone of modern astrophysics.

The most important discoveries of the 18th century include those of Uranus and Neptune. The absorption lines in the sunlight spectrum were discovered in the 19th century. They could later be used to determine the chemical composition and other physical properties of the sun and other stars. At the beginning of the 20th century, the concept of space and time was fundamentally changed by the work of the physicist Albert Einstein. According to his theories, which were later to be confirmed, time and space are not absolute quantities, but depend on the viewer and his movement. In addition, according to Einstein's general theory of relativity, space is curved by masses. This phenomenon can be observed through the gravitational lensing effect. Another fundamental finding of the 20th century is the fact that the entire universe is expanding. In conclusion, this means that this expansion must have started at one point - the Big Bang. On February 18, 1930, Pluto was discovered and classified as the ninth planet in our solar system. However, since other objects of its size were found in similar orbits, it has been counted among the dwarf planets of the Kuiper Belt for several years. The middle of the 20th century was the beginning of the space age. For the first time, it enabled direct exploration of alien heavenly bodies. Radio astronomy was also invented at this time (picture). The sky could now also be observed in the invisible part of the electromagnetic spectrum. In 1990 NASA launched the Hubble space telescope. It enabled high-resolution photographs of the cosmos without being disturbed by the earth's atmosphere. Shortly before the beginning of the 21st century, it was possible for the first time to detect planets orbiting other stars - so-called exoplants.

The Modern Age on Wikipedia
alpha-Centauri Video: How do you measure distances in space? part One
alpha-Centauri Video: How do you measure distances in space? Part II
alpha-Centauri Video: How do you measure distances in space? Part III