One of the greatest mysteries of the universe is that endless trillions of stars are not scattered evenly in outer space. No, stars are grouped into galaxies, just like people gather in cities, leaving the spaces between them uninhabited.
The name of our Galaxy is the Milky Way. This is a huge rotating flat disk, consisting of gas, dust and about 200 billion stars. The distance between neighboring stars in the galaxy is trillions of kilometers of empty space. Our Sun, one of the many stars that inhabit the galaxy, is located on its periphery.
Milky Way Galaxy
When we look into the night sky, we look through the stars, as through raindrops adhering to the window pane. All the individual stars that we see in the sky belong to the Milky Way. Our galaxy has a spiral shape. From above, it looks like a whirlwind of stars. Stars revolve around the center of a galaxy, just like planets revolve around stars.
To make one revolution in this starry carousel, the Sun takes about 200 million years, and it moves at a speed of no less than 940,000 kilometers per hour. From the side, the galaxy looks like a disk with an elevation in the center. A bright white streak crossing the sky on a clear night is part of this disc.
Other galaxies
This is how we see our galaxy. If we could get beyond it, we could see the Universe in all its pristine beauty: a huge impenetrable - black space, on which brightly lit galaxies are scattered, like illuminated islands in the night sea.The Milky Way itself is a huge space formation, but this is only one of the 100 billion galaxies available for observation of space.
Although each galaxy is an accumulation of millions of suns, they are located so far from us that they are perceived as rather dim nebulae. With the help of a small telescope, you can see several dozen galaxies. Well, if you use the most modern powerful telescope, then you can not only consider many galaxies, but also make out individual stars in some galaxies.
Galaxy Andromeda Nebula
On a very clear night, it is sometimes possible to discern the Andromeda Nebula Galaxy, the closest neighbor of the Milky Way. And for this, no optical device is needed. Just like the Milky Way, the Andromeda nebula is a spiral. More than half of all galaxies have a spiral shape. Such galaxies, similar to the wheel of a rustic spinning wheel, contain new, old and middle-aged stars.
Galaxies of a different form
There are elliptical galaxies. These are huge rounded balls consisting of billions of stars. Some of these galaxies are almost perfectly round, others are slightly flattened. In elliptical galaxies, stars rotate very closely around the center, resembling a swarm of bees. Most often, elliptical galaxies are made up of old stars, many of which are red giants.
Therefore, elliptical galaxies almost always glow in red or orange. There are galaxies and other forms.There are galaxies resembling a biconvex lens in shape, or spiral galaxies without a thickening in the center. There are galaxies that do not have any form at all. Such galaxies are called irregular.
Galactic events
Although the galaxies look like peaceful and serene clusters of stars, their appearance can be very misleading. These worlds serve as the arena of the strongest natural shocks, the galactic equivalent of earthquakes and volcanic eruptions. Here is a modern example. From the center of the M87 galaxy there was a monstrous surge of blue - white hot gas. A huge amount of energy was released into space. The fiery tongue of the ejected gas is about 5,000 light-years long. Scientists think that the black hole in the center of the galaxy, absorbing cosmic dust and whole stars, is the source of this awesome - majestic view.
Collisions of galaxies
Sometimes galaxies collide with each other. Since there is a lot of empty space between the stars of galaxies, galaxies usually freely go their own way without “noticing” collisions. Due to the huge size of galaxies, such collisions do not last for several minutes, but several million years. Scientists in such cases simulate a collision on a computer. Thus, it is possible to show what will happen when the galaxies come in close contact, and how they will look after it. When one galaxy invades another, they begin to act on each other with their gravitational fields.
In this case, the stars are displaced from their previous positions, destroying the original shape of the galaxy. For example, the curl of a spiral galaxy can stretch toward an approaching elliptical galaxy. Two galaxies can merge after a collision, forming a new galaxy larger than the two original ones.
How are galaxies formed?
Some scientists suspect that modern impossibly large galaxies were formed from the merger of smaller star clusters. For example, an elliptical galaxy may form from the merger of two spirals. Galaxies that are 2 million light-years distant from us are now available for observation. This means that astronomers see galaxies as they were 2 million years ago. So, the more ancient galaxies we see, the smaller they become. Moreover, small ancient galaxies are usually shapeless. Scientists believe that the formation of such a spiral galaxy as our Milky Way requires the fusion of 10 - 100 small galaxies.
