We reveal the usual boundaries.
If you ask any of us about the place of residence, the answer is likely to be the name of the city or village, street, house, apartment. Maybe someone will name another country, or some other prankster will say that he lives on the planet Earth. That’s how we live on Earth, and not all of us know what place it occupies in the vast Universe.
It is the place of our Earth in the universe that is our astronomical address . Why is it needed? It is not necessary to specify it in the letters, it is not written in the passport — so maybe it is better without it?
But this is the answer of a person who lived in some thirteenth century AD, who considered his village to be the whole world. He thought that the Sun was setting behind these hills, and rising behind such and such a stream. And a person of the twenty-first century should also know his astronomical address, because we should differ from our distant ancestors not only in the ability to climb the Internet,but also in understanding the picture of the world.
On the other hand, when you study all these abysses of space that take place in astronomy, it becomes really scary, you realize what a grain of sand you are on the scale of the vast universe. And it begins to seem that it would be better not to know such things, but to live in your own little world and not think about such distant and incomprehensible substances. Of course, the peculiarities of perception are different for everyone, but I personally still believe that such a contemplation of the infinite does not detract from our significance, but shows us that we are part of something larger, something vast, which sometimes makes us look at our petty problems in a different way. And if you still decide to find out our true place in the universe, then you can safely read on. I hope you will discover something new.
From Earth to the Solar System.
The first point of our astronomical address will be our planet Earth. This is a rather unusual planet, which has a unique composition of the atmosphere, huge oceans on its surface, protected from external radiation by a powerful magnetic field, the ozone layer and the ionosphere. The Earth is located at a distance of 1 astronomical unit from the Sun.
It is not difficult to guess that the very concept of an astronomical unit arose as a reference value. If we translate this distance into kilometers, we get the distance of the maximum distance of the Earth from the Sun-Aphelion, equal to about 152 million kilometers. That’s how far our planet is from the Sun. Or is it close?
Apparently, it is still close, because, for example, Pluto, which is almost on the border of our Solar System, is already located at a distance of 12 billion kilometers, or 80 astronomical units. Such is our huge planetary system. And the main place in it is occupied not by the planets, but by our Star-the Sun, which makes up about 99% of the mass of the entire Solar System. It is not difficult to calculate that all the planets, including not only the tiny Earth, but also the giant Jupiter, make up less than 1% of its mass.
It really makes you think about our place in the universe. In the Solar system, the Earth, despite all its features, is just one of the planets of the Earth group, which, in addition to it, includes Mercury, Venus and Mars.
From the Sun to the Milky Way.
But we will move on — we realized that we are among the planets of the Earth group, in the Solar system, which is based on the star Sun. To better understand all the scales, it is worth noting that our Sun, which from the Ground looks like a small bright lantern, actually has a diameter equal to almost 109 diameters of the Earth.
“What a huge Sun!” – the thought comes to mind. However, by the standards of the galaxy, it is just an ordinary yellow dwarf, a very small and inconspicuous star. Among the bright tribe of stars, there are also colossal red giants that are thousands of times larger than the Sun. Here is such a scale!
Of course, the Sun is also part of an even larger system. And such a system is our galaxy — the Milky Way . It is a part of it that is visible on a clear, moonless night, like a misty streak that runs through the entire sky. If you look at this band with binoculars, you will see a huge number of stars. And indeed, in our galaxy, in addition to the Sun, there are about 200 billion stars, although some scientists are of the opinion that there are twice as many. All these stars make up a huge spiral that rotates around its center.
Our Sun occupies a far from central position in this stellar scattering, being located in one of the branches of the spiral-in the Orion arm. And, like billions of other stars, it orbits the center of the galaxy. At the same time, the Sun is located closer to the periphery at a distance of about 26 thousand light-years from this center. That is, if we fly there at the speed of light, it will take millennia before we reach the core of the galaxy.
From the Galaxy to infinity.
Here we have reached the huge Milky Way galaxy, with a diameter of 100 thousand light-years, which in the form of a spiral disk consisting of myriads of stars, rushes through space and time. But our galaxy is not alone in the universe. There are a huge number of them — modern astronomers can currently observe 100 billion galaxies. But, apparently, there are much more of them.
Our galaxy has neighbors — the Large and Small Magellanic Cloud and the Andromeda galaxy. Together with its neighbors, the Milky Way is part of the local group of galaxies. In addition to these, it includes about 50 other systems.
The local group of galaxies is, in turn, part of the Virgo galaxy supercluster, which covers galaxies within a radius of 200 million light-years and contains about thirty thousand galaxies.
The scale is amazing, it introduces a kind of awe before the grandiosity of such systems. But what’s next? Next, we can isolate the part of the Universe that we can observe in all the instruments available to us — it is called Metagalaxy. Then there is the entire Universe as a whole, the presence of boundaries in which modern physics, although it recognizes, but their exact definition is still only at a hypothetical level.
In front of us is a chain that almost goes to infinity — our astronomical address :
Earth-Earth Group planets-Solar System-Orion Arm-Milky Way galaxy-Local Galaxy group — Virgo Supercluster-Metagalaxy-Universe.
I hope that now, looking at the starry sky, you will understand how grandiose the scale of our Universe is. And how insignificant and at the same time great is the importance of man in it. One day we will master the Solar system, then we will go deep into our galaxy, but even then we will be just grains of sand on the shore of the vast ocean of the Universe. But this only means that we will always have something to strive for, that there will be no limits to our development, except those that we set ourselves.
If this article made you take a break from the hustle and bustle of our earthly life and look into the depths of the universe, at least in your thoughts, then I did not write it in vain.