More than anything else – the Universe itself, covering and including all planets, stars, galaxies, clusters, superclusters and cells. The range of modern telescopes reaches several billion light years.
Planets, stars, galaxies amaze us with an amazing variety of their properties, the complexity of the structure. And how is the whole universe, the universe as a whole?
Its main property is uniformity. This can be said more precisely. Imagine that we mentally allocated a very large cubic volume in the Universe, with an edge of 500 million light years. We calculate how many galaxies are in it. Let’s make the same calculations for other, but equally gigantic volumes located in different parts of the universe. If you do all this and compare the results, it turns out that each of them, wherever they are Continue reading
By the beginning of our century, the borders of the explored Universe had moved so far that they included the Galaxy. Many, if not all, then thought that this huge star system was the whole Universe as a whole.
But in the 1920s, new large telescopes were built, and astronomers opened up completely unexpected horizons. It turned out that the world does not end outside the galaxy. Billions of star systems, galaxies, similar to ours and different from it, are scattered here and there in the vastness of the universe.
Photos of galaxies made with the help of the largest telescopes are striking in their beauty and variety of shapes: these are powerful vortexes of star clouds, regular balls, and other star systems do not detect any specific shapes at all, they are ragged and shapeless. All these types of galaxies – spiral, elliptical, irregular – that got their names in appearance in photographs, were discovered by the American astronomer E. Hubble in the 20-30s of our century.
If we could see our Galaxy from afar, then it would appear before us quite different from the one in the schematic Continue reading
Since the XVII century, the most important goal of astronomers has been the study of the Milky Way – this giant collection of stars that Galileo saw through his telescope. The efforts of many generations of observer astronomers were aimed at finding out what is the total number of stars of the Milky Way, determining its actual shape and boundaries, and estimating its size. It was only in the 19th century that it was possible to understand that this is a single system that contains all the visible stars. On an equal footing with all, our Sun enters into this system, and with it the Earth and planets. Moreover, they are far from being located in its center, but on its outskirts.
It took many decades of careful observation and deep thought before the structure of the Galaxy was revealed to astronomers in its entirety. So they began to call the star system that we see – of course, from the inside – like a strip of the Milky Way. (The word “galaxy” is derived from the Greek “galacticos”, which means “milky.”)
It turned out that the Galaxy has a fairly regular structure and shape, despite the apparent raggedness of the Milky Continue reading