How big are galaxies?

Together with the stars, the galaxy is the most important unit of the organization throughout the universe. There are estimated 100 billion galaxies in a visible universe, each with about ten million and trillion stars. The average galaxy involves about 10 atoms 71 and ten times more invisible matter in the form of dark matter. The galaxies themselves tend to be arranged in large structures called superklasters, which in turn are arranged in massive filaments separated by huge cavities. The largest of these gratu, supercar Eridanus, has an average of almost 1 billion light -years, about 10,000 times wider than the Milky Way galaxy. To get the size of its scale, if 100 billion human beings could occupy space around every star, then the whole galaxy could provide space for about 10

22 , more thp sand of sand on all earth beaches. The galaxy is only about 100,000 light -years and 1,000 fat lights.

This means that the whole galaxy could be colonizalFor just a million years, about four times the time the human species existed, using steamships of passengers at 1% of light speed. Most of the visible stars in the galaxy are the main sequential stars, similar to our sun. The minority is red giants, playing much larger than our sun, but very scattered.

Although our galaxy is large-100,000 light-years-year-olds-it is small enough that if civilizations focused on expansion have appeared in the first 99.9% of its history, they would have already been there. This is a strong argument for the absence of extraterrestrial civilizations in our galaxy. It is possible that such civilizations have only recently appeared, but and priori and priori the possibility of such a recent origin is relatively low, of the order of 1 in 10 000 or 1 in 100,000, if the probability of developing is evenly distributed over most of the galaxy existence.

The galaxy of the Milky Way is not a loner, but it's actually binaryGalactic system, gravitationally locked to our sister Galaxy, Andromeda Galaxy, about 2 million light -years. Our galaxies and Andromeda are members of the local group, a collection of more than 35 galaxies. The Milky Way is considered the smallest, although perhaps the second largest, after Andromeda. The local group itself is built into a larger SUPER KLUSTER Virgin, which contains more than 100 galaxies measuring 110 million light -years.