What is between galaxies?

Everything that astronomers know about the universe is knownthanks to the observations. Peering into the depths of space, the Hubble Space Telescope sends images of distant stars, planets and galaxies to our planet. According to scientists, only in the observable Universe there are about two trillion galaxies. It is hard to imagine, but thanks to the photographs we have some idea about them and their location. Astronomer Edwin Hubble in 1925 identified several types of galaxies: elliptical, irregular, ordinary spiral, crossed spiral and lenticular. It turns out that scientists know what galaxies are and what happens inside them, but do they know what is between the galaxies?

15 thousand galaxies in the lens of the Hubble telescope

What is a galaxy?

To start with the example of the Milky Way, let'sLet's see what galaxies are. So, a galaxy is a huge gravitationally coupled system. It contains about 200 billion stars, as well as nebulae, dark matter, planets, clouds of dust and gas, as well as star clusters. All objects located in the galaxy participate in motion relative to the common center of mass. In the very heart of the galaxy is a supermassive black hole, which, by the way, according to scientists, has recently behaved quite strangely.

It looks like the center of the Milky Way

Depending on species, according to classificationEdwin Hubble, each galaxy has its own characteristics. So, the Milky Way in its shape in profile is vaguely similar to a “flying saucer”. And not so long ago, scientists found that our galaxy is not at all flat, as previously thought - it turned out that the Milky Way is more like an accordion, since the galaxy seems to be wrinkled closer to the edges.

The distance between galaxies is extremely large. So, the closest Andromeda galaxy to us is located at a distance of 2.5 million light years from Earth. It’s hard to imagine such a distance. But what is between the galaxies?

By the way, we can discuss whether our galaxy will encounter the Andromeda galaxy in our Telegram chat

Another mystery of the universe

Shortly after the Big Bang, the Universe wasfilled with gas, mainly hydrogen. Over time, here and there, gravity began to draw gas to the clouds, which later turned into galaxies inside which stars were born. Do you know why the stars are shining? The thing is the thermonuclear combustion of hydrogen - those stars that turn into supernovae and die after the explosion “push” the gas back from the galaxies.

There in a mysterious intergalacticspace, the gas cools and becomes denser. There he is, until the force of gravity pulls him back into the galaxy, where new stars form. The process repeats itself: gravity condenses gas into galaxies and stars, stars explode and emit gas, gravity attracts gas again and new stars are born.

Hubble telescope took a picture of a supernova explosion

Over time, in any galaxy beginsrun out of processed gas. And without gas, new stars cannot form in the Universe; old stars live their lives and die, and ultimately the galaxy also dies. Galaxies live in the so-called gas bath, the environment from which they were born, and which feeds them. Galaxies inhale and exhale gas, and the stars continue to burn until the gas disappears. Sounds nice, right?

Read even more amazing facts about the Universe on our channel in Yandex.Zen

What does the universe consist of?

There used to be a problem with testing this theoryconsisted in the fact that astronomers' instruments were barely able to detect signs of intergalactic gas, not to mention its appearance and disappearance. However, today, thanks to more sensitive tools, scientists know much more. The data obtained indicate that the intergalactic environment is rich in gas, which fills the Universe and generates galaxies. Slightly less convincing, and sometimes mysterious evidence in a near-galactic environment shows that galaxies live by recirculating gas to and from stars.

And here is evidence that galaxies cangas will end, and stars will cease to be born, which will lead to the death of the galaxy so far only preliminary. The fact is that even in the young Universe, gas is not homogeneous. The intergalactic medium is also not pure hydrogen: it is partially filled with elements heavier than hydrogen, which appear when stars explode and die.

Scientists: Our galaxy is like the English letter S

And yet, despite many questions, scientistsagree that this ancient, cooling, sparse intergalactic environment is a well-understood entity that contains a convincing picture of when and from which galaxies arose.

However, despite the emergence of new toolsand the joint work of scientists, today there is no general picture of the birth, life and death of galaxies. To better understand this, scientists are resorting to computer simulations - recently astronomers have created 8 million galaxies inside a computer. Regardless of whether the simulations are real or not, it is with their help that scientists will be able to get answers to questions about the nature of intergalactic gas. The fact is that simulations are the clearest visualization of how gas could create galaxies.

Scientists believe that today, 13.8 billion yearsafter the Big Bang, only 60% of the gas is concentrated in the intergalactic environment; the rest is in the vicinity of the galactic medium and inside the galaxies. It turns out that in the vastness of the Universe, galaxies are strung on voids, similar to illuminated highways. Handsomely! Despite the fact that a lot remains a mystery.