Indeed till the present day, it cannot be ascertained that how many stars are there in the universe or how far are they from each other. Recently on April 25, 2018, the European astronomers published a catalogue which is the most accurate of all the catalogues that have ever come up.
This catalogue provides data collected as a result of 22 months of observation by their Gaia satellite. Gaia is a space observatory of the European Space Agency (ESA) designed for astrometry: measuring the positions and distances of stars with unprecedented precision. It provides parallaxes for over 1.3 billion stars in the local part of the Milky Way, along with positions and brightness of almost 1.7 billion stars in totality. This release of data by the ESA is the second release and is way better than the first one. The first release only covered 2 million stellar distances. Parallax provides a method to measure stars’ distances using pure geometry, as long as astronomers are aware of the distance between the Sun and Earth. But parallaxes are usually smaller than an arc second — the farther is the star, the smaller is its parallax. Because atmospheric turbulence also causes stars to “wobble,” parallaxes of stars more than a few dozens of light-years away are measured in the best possible way from space.At the time of its rotation around the sun, Gaia satellite covers the entire sky, measuring each star again and again. Until now Gaia has covered over 14,000 known solar system objects including asteroids. These provide measurements that provide for a more precise calculation of their Orbits.
By: Anuja Arora