Outer space — answers to frequently asked questions
In the Middle Ages, Europeans’ representation of the cosmos was based on the treatise Almagest created in the 2nd century BC, when the Earth was considered the center of the universe. Modern understanding originates in the XVI century, from a heretical Copernican assumptions: What seems to us as a movement of the Sun, comes not from its motion, but from the motion of the Earth… Although this picture was later supported by calculations of Kepler and Galileo’s observations made using the telescope, it seemed controversial for a century more, till the advent of Newtonian mechanics. At the beginning of the XX century, astronomical observations led to the conclusion that the stars are grouped into galaxies, which diverge from each other, i.e. the universe is expanding. By the end of the century the sensitivity of telescopes allowed to look at the vast distances, from which the light went billions of years, in an era when the universe was different. With the help of optical, radio, and neutrino astronomy detailed information has been gathered about millions of space objects — galaxies and quasars.