The universe: It is infinitely huge and contains everything we know and maybe much more. But how big is it? Does it have a border or a center and does it really expand?
The universe is big, no question, only the planet we live on, the earth, has a diameter of about 13,000 kilometers and our corresponding sun already 1.4 million kilometers. Together with the other planets in our neighborhood we have the solar system, which extends over 300 astronomical units. One astronomical unit, in short AU, stands for the mean distance earth-sun, i.e. 150 million kilometers.
Our galaxy, the milky way, with its approximately 300 billion estimated stars (for now, this can change in the future), has a size of 100 thousand light years. The distance in which the light travels in 100,000 years. Together with at least 70 other galaxies, our milky way forms a cluster of galaxies called the local group, which covers an area of about 10 million light years. But it can be even bigger. At least 100 such galaxy clusters form a supercluster. It has a breathtaking 200 million light years in diameter.
But even that is small compared to the so-called galaxy filaments. These huge spiderweb-like structures run through the whole universe. The largest filament discovered to date is the Hercules Corona Borealis Great Wall and extends over an unimaginable distance of over ten billion light years.
This astronomical wall and the structures mentioned now form the universe, or better said, the universe we can observe. But in fact we are not in a position to grasp the universe in its entirety. The reason for this is the temporal origin of 13.8 billion years, ago. The light of the observed objects in the sky above us can therefore only have been on the move for a maximum of 13.8 billion years. One could therefore conclude that the objects we see are no more than 13.8 billion light years away and that the observable universe ultimately extends over 27.6 billion light years. But it doesn't. Due to the expansion of the universe, i.e. the expansion of space and time.
Out of singularity, everything in the universe moves away from each other. Similar to painted dots on a balloon that you inflate. The source of the light that was sent 13.8 billion years ago is now 46.6 billion light years away. The observable universe is therefore 93.2 billion light years in size and grows with every second.
We have no idea about the real size, the boundaries and the center of the observable universe. What hides behind our horizon is beyond our imagination and the universe itself have probably no limits, we don't know it.
But let us agree that the universe is simply unimaginably large and that you are probably nothing in relation to what surrounds you. But hey, look at it positively! At least you are the center of your own observable universe! And that is all that matters!