Galaxy in space

Galaxy in space

Astronomy Solar system

Galaxy in space

Galaxy in space- We live on a planet called Earth, which is part of our galaxy’s solar system. But where is our solar system? A small part of the Milky Way galaxy that you can read about in detail in the Solar System and the Milky Way galaxy.

A galaxy is a huge collection of gas, dust, stars, and its solar system. The components of a galaxy are held together by gravity. Our Milky Way galaxy has a very heavy black hole in the middle, and the very high gravity of this black hole causes the galaxy’s components to stick together.

Galaxy in space- When you look at the stars in the night sky, you see other stars in the Milky Way galaxy. If the place where you are standing is dark and away from the light of cities and houses, you can see the dusty groups of the Milky Way stretched to the sky.
There are so many galaxies besides us that there are so many that we may not even be able to count them all!

The Hubble Space Telescope surveyed a small space in the sky for 12 days and was able to observe 10,000 galaxies of all sizes, shapes, and colors. Some scientists believe that there are more than one hundred billion galaxies in the universe.

Galaxy in space- Some galaxies, like ours, are helical. They have curved arms that make it look like a gear. Other galaxies are flat and oval and are called elliptical galaxies.

Some galaxies are not spiral or oval. They are irregular in shape and look like bubbles. The light we see from each of these galaxies comes from the stars inside those galaxies.

Types of galaxies

Sometimes galaxies get too close to each other and collide with each other. Researchers believe that our Milky Way galaxy will one day collide with Andromeda, the nearest galaxy around us. But this is nothing to worry about right now because it will happen in about five billion years.

Galaxy in space- However, even if this happens tomorrow, you may not notice it because galaxies are so large that even if they collide, their planets and solar systems often do not collide.

Types of galaxies

Before the 20th century, scientists did not know of galaxies other than the Milky Way. Previous researchers had classified them as “nebulae” because they looked like fuzzy clouds.

Nebula Galaxy

But in the 1920s, the famous astronomer Edwin Hubble showed that the Andromeda Nebula is a galaxy of its kind, but because it is so far away from us, it takes more than 2.5 million years for light to pass through Andromeda and reach us. Despite its great distance, Andromeda is the closest large galaxy to the Milky Way and is so bright in the night sky that it can be seen with the naked eye in the Northern Hemisphere.

Andromeda Galaxy

In 1936, Hubble proposed a way to classify galaxies, classifying them into four main types:

Spiral galaxies
Lens galaxies
Elliptical galaxies
Irregular galaxies
The following are the main features of these galaxies.

Spiral Galaxy
A combination of the galaxy Messier 81 (M8) and Andromeda represents what astronomers call a large spiral galaxy in which each arm is bent to the center. M81, which is about 12 million light-years away and is located in the constellation Ursa Major, is one of the brightest galaxies visible to Earth from a telescope.
The most famous spiral galaxies are:

Andromeda Galaxy – A spiral galaxy in the local group
The Milky Way – A spiral galaxy containing our solar system
Spinning Galaxy – A spiral galaxy in the constellation Ursa Major
Sunflower Galaxy
Galaxy Triangle
Whirlpool Galaxy

Spiral galaxies are made up of several distinct parts:

A flat, rotating disk of stars and interstellar matter whose helical arms are prominent components.
A central star protrusion from mostly older stars that resembles an elliptical galaxy.
Distribution of star-shaped bars
Almost spherical halos of stars, including many halos in spherical clusters
Large black holes in the center of the central bulge
An almost spherical halo of dark matter
The relative importance of the various components of this type of galaxy varies from galaxy to galaxy in terms of mass, brightness, and size.

Spiral arms
Spiral arms are areas of stars that branch off from the center of closed, spiral galaxies. These narrow, long regions resemble spirals, hence the name spiral galaxies. Naturally, the different classifications of spiral galaxies have distinct arm structures.

For example, the galaxies Sc and SBc have very weak arms, while the galaxies Sa and SBA have strong, closed arms. In any case, the arms of spiral galaxies contain a large number of young, blue stars that make the arms very bright.

Galactic bulge
A bulge is a large, completely closed group of stars. This term refers to the central group of stars found in most spiral galaxies. Using Hubble classification, Sa galaxies usually protrude from population stars

It is composed of red and old stars with low metal content. Also, the protrusions of the galaxies Sa and SBA are large.

In contrast, the galaxies Sc and SBc are much smaller and are composed of young, blue stars. Some protrusions of spiral galaxies have properties similar to elliptical galaxies.

Many bumps are thought to have a large black hole at their center. For example, in our galaxy, the Milky Way, there is a body called ⋆A Sagittarius Researchers believe that this object is a large black hole.

There is ample evidence for black holes at the centers of spiral galaxies, including active nuclei in some spiral galaxies, and dynamic measurements that have found large compact central masses in galaxies such as NGC 4258.

Star bar
Stars containing rods are found in about two-thirds of spiral galaxies. The presence of these star bars may be strong or weak. Inspiral galaxies and edge lens galaxies, the presence of a star bar can sometimes be identified by a structure protruding from the X-plane or peanut-shaped.

Star Hale

The mass of stars in a spiral galaxy is either close to a single plane (galactic plane) in circular orbits around the center of the galaxy or in a sphere around the galaxy’s core.

However, some stars are in a spherical halo or on a cosmic sphere, which is a type of galactic halo. The orbital behavior of these stars is debatable, but they may show inverted or deviant orbits, or they may not move in regular orbits at all.

Star auras may form from small galaxies that merge into a spiral galaxy and merge.

The dwarf spherical galaxy Sagittarius, for example, is in the process of merging with the Milky Way, and observations show that some of the stars in the Milky Way halo formed from this galaxy.

Unlike the galactic disk, the halo appears to be dust-free, and as a result, the stars in the galactic halo are of a population that is much older in age and much lower in metal than their cousins ​​in the galactic disk population. However, the type of stars in a halo is similar to that of stars in a galaxy.

Elliptical galaxies

The names of elliptical galaxies are derived from their appearance. These galaxies are generally round but can be stretched along one axis more than the other so that some of them look like cigars.

The world’s largest known galaxies are giant elliptical galaxies that can hold up to a trillion stars and cover a range of two million light-years. Elliptical galaxies may also be small, in which case they are called dwarf elliptical galaxies.

Elliptical galaxies contain large numbers of old stars, low dust, and interstellar matter. Their stars, like those in the disk of spiral galaxies, orbit the center of the galaxy, but they rotate in random directions. A small number of new stars are also known to form elliptical galaxies. These stars are also common in galaxy clusters.

Types of elliptical galaxies include the following:


The main feature of elliptical galaxies is several things that distinguish them from other classes of galaxies.

They are spherical or elliptical masses of stars left over from stellar gases.
The smallest known elliptical galaxy is about one-tenth the size of the Milky Way.
The motion of stars in elliptical galaxies is mostly radial, unlike the disks of spinning galaxies.
These galaxies contain very little interstellar matter (neither gas nor dust), which leads to slow star formation, open

star clusters, and young stars.

Older stars are found in these galaxies, which is why the color of these galaxies is red.
Large elliptical galaxies usually have an extensive system of spherical clusters.
The dynamic properties of elliptical galaxies and the protrusions of disk galaxies are similar, suggesting that the two groups may have been formed by similar physical processes.

The study of data on the luminosity of elliptical galaxies and ridges is fully consistent with Cersic’s law and explains a wide range of relationships between the structural parameters of elliptical galaxies and their populations.

Cersei’s law (or Cersic model or Cersic index) is a mathematical function that describes how the intensity of Galaxy I changes with distance from its center, R.

Each massive elliptical galaxy contains a large black hole at its center. Observations of 46 elliptical galaxies, 20 classical protrusions, and 22 quasi-protrusions show that each has a black hole at its center. The mass of a black hole is closely related to the mass of a galaxy.

Elliptical galaxies are commonly found in galaxy clusters and smaller groups of galaxies. Unlike galaxies with a flat spiral structure, more three-dimensional elliptical galaxies have no additional structure, and their stars are randomly around the center.

Lens galaxies

Lens galaxies, like the iconic Sombrero galaxy, lie between elliptical and spiral galaxies. These galaxies are called lens galaxies because they look like lenses. Like spiral galaxies, these galaxies have a thin, rotating disk of stars and a central bulge, but no spiral arms. Also, like elliptical galaxies, these galaxies have little dust and interstellar matter and appear to form mostly in densely populated areas of space.

Irregular galaxies

Galaxies that are not spiral, lens, or elliptical are called irregular galaxies. Irregular galaxies, such as the large and small Magellanic Clouds adjacent to the Milky Way, appear malformed and lack a definite shape. This is often because these galaxies are affected by the gravity of other nearby galaxies. These galaxies are full of gas and dust, which makes them a good place to form new stars.

The Coddington Nebula, or IC 2574, is an irregular dwarf galaxy moving away from us at 55 kilometers per second. It is about 50,000 light-years across and is located about 12 million light-years away in the northern constellation of Ursa Major. IC 2574 is a member of the Andromeda Galaxy Group (Messier 81).

According to researchers, the first stars in the universe formed about 180 million years after the Big Bang. Studies show that the Big Bang occurred 13.8 billion years ago, which is known as the origin of the universe.

World history with the onset of the Big Bang. One billion years after the Big Bang, hydrogen atoms mysteriously decomposed into ion soup.

According to the evidence, the formation of the first galaxy occurred due to gravity at a time when the universe was only 400 million years old or less than 3% of its current age.

Astronomers now believe that almost all galaxies, except some, are embedded in huge halos of dark matter. Theoretical models also show that early in the universe, large amounts of dark matter provided the gravity needed to collect normal matter in the first galaxies.

But there are still unanswered questions about how galaxies form. Some believe that galaxies are made up of smaller clusters of about one million stars known as spherical clusters, while others believe that galaxies formed first and then spherical clusters were born.

It is also difficult to know how many stars in one galaxy formed from the galaxy’s gas or formed in another galaxy and later joined the galaxy. The answer to these questions may be possible by accessing powerful telescopes and observing the beginning of the universe.

What is the size and mass of galaxies?

The mass of most galaxies between 107 M⊙ And  Is (the meaning of M⊙ It is a standard unit of mass in astronomy and its value is approximately equal 2×1030Kg).

Their size, and indeed their diameter, is in the order of a few kiloparsecs (a parsec is a unit of length used to measure large distances of extraterrestrial astronomical objects. It is approximately equal to 3 \ 3 light-years) up to more than one hundred kiloparsecs.

The Milky Way as a galaxy contains more than 100 billion stars, including the Sun, and its stellar disk is estimated to be about 50  kiloparsecs in diameter. Also, the size of a halo of spherical stars up to 100 k pcs, and the size of a halo of dark matter maybe even more.

Galactic clusters and their integration
The galaxies in the universe are constantly changing through evolution, integration, and interaction with other galaxies. At the beginning of the universe, which did not yet form stars in galaxies, there were clusters of galaxies called the early galaxies, which consisted only of dark matter and gas.

It is assumed that some of these early galaxies may still exist, and in fact, there may be clusters of dark galaxies that do not have the conditions to form stars. These galaxies are made only of dark matter and gas.

Some galaxies are single and others exist in pairs. But in any case, most of the time these galaxies are part of larger clusters known as clusters, clusters, and superclusters. Our Milky Way, for example, is part of a local group that is about 10 million light-years old, including the Andromeda Galaxy and its satellites.

The local group and its neighboring galaxy clusters, the Virgo Cluster, are both located in the largest Virgo supercluster. The Virgo supercluster contains the dense space of galaxies estimated to be about 100 million light-years across.

The Virgo supercluster is also part of Lania kea, a cluster of 100,000 galaxies discovered by astronomers in 2014.

Galaxies in clusters are often in a dynamic interaction with each other due to the force of mutual gravity, which causes them to even merge.

When two galaxies collide and merge, gases flow toward the center of the galaxy, which can cause phenomena such as the rapid formation of stars. Researchers predict that the Milky Way will merge with the Andromeda Galaxy in about 4.5 billion years.

The collision of the Milky Way and Andromeda

Andromeda is 22,000 light-years across, twice the diameter of the Milky Way. Andromeda has 1 trillion stars, which is twice the number of stars in the Milky Way. This galaxy is 2.5 million light-years away and is approaching our galaxy at a speed of 120 kilometers per second. Andromeda and the Milky Way are estimated to collide in another 4.5 million years.

How many galaxies are there in the universe?

In total, Hubble estimates that there are about 100 billion galaxies in the universe, but with the advancement of telescope technology in space, that number is likely to increase to about 200 billion galaxies.

In 1995, astronomers adjusted the telescope to empty areas called Ursa Major and collected their 10-day observations. Summarizing the results showed that there are more than 3,000 small galaxies in a frame of magnitude 30. (To compare the luminosity of these galaxies, for example, the luminosity of a northern or polar star is approximately 2).

Ursa Major

Called the Hubble Deep Field, it was the farthest distance anyone could see at the time.

With the development of imaging techniques for the Hubble Space Telescope, astronomers repeated the experiment twice more in 2003 and 2004. Scientists have expanded the Hubble Ultra Deep Field to see about 10,000 galaxies at a small point in the constellation Fornax in less than a million seconds.

The constellation Fornax is unknown in the Southern Hemisphere. The Fornax galaxy is part of this constellation and is one of the largest galaxy clusters, 60 million light-years away, second only to the Milky Way.

In 2012, scientists explored part of the eXtreme Deep Field using updated instruments using the Hubble Space Telescope. They found that even with limited space, there were about 5,500 galaxies.

How galaxies form

The appearance and arrangement of galaxies over billions of years have been shaped by interactions with groups of stars and other galaxies. Although we do not know for sure how galaxies formed and evolved into the various forms we see today, we do have ideas about their origins and evolution. Using supercomputers, scientists can look back and simulate how a galaxy formed early in the universe and became what we see today.

Astronomer Edwin Hubble’s observations led to the idea that the universe was expanding. Scientists estimate the age of the universe to be 13.8 billion years based on the rate of expansion.

The deeper you look at space, the more details you get about the history of the universe. It can be concluded that galaxies are billions of light-years away and formed immediately after the Big Bang. While most galaxies formed early in the universe, data show that some galaxies formed in the last few billion years, not a few billion years from a cosmic point of view.

The early universe was mostly filled with hydrogen and helium, and some areas were slightly denser than others. These dense regions slow the expansion of the universe, allowing hydrogen and helium to accumulate in tiny clouds orbiting space. Gravity causes the gas in these clouds to collapse and form the first generation of stars, but the early stars burn quickly.

Gravity also causes clouds to collapse. As clouds get closer to each other, gravity deflects them toward each other, turning the clouds into larger, rotating clusters. As more clouds combine, these large, rotating assemblies become rotating disks that collect more gas and dust. With the formation of new stars, wide spiral arms of stars are formed. At this time, spherical clusters with a halo of gas, dust, and dark matter line the perimeter.

Although the Hubble Space Telescope is unable to see the first galaxies, it can trace the evolution of galaxies over a long cosmic time. The collection of Hubble in-depth images and other in-depth studies of galaxies at different distances in the universe and at different times of evolution have shed light on many facts about the formation of galaxies.

Farther away galaxies, seen early in the universe, have simpler structures. The nearest galaxies that form and observe as the universe ages have grown to resemble the familiar galaxies we see in the universe today.

List of galaxies discovered in the universe

The universe includes its place, time, and contents, including planets, stars, galaxies, and all other forms of matter and energy.

As we have said, a galaxy consists of the stellar systems and interstellar matter that make up the universe. In this section, we introduce several galaxies that are widely used in various researches.

Man has always been curious and eager to discover the secret of the universe. This curiosity leads him to discover the wonders of the world and the splendor of the universe that has never been seen before. The list of galaxies below is a clear result of this curiosity.

It is a spiral galaxy about 2.5 million light-years from Earth and is the closest large galaxy to the Milky Way. This galaxy is the largest member of the local cluster, which also houses the Milky Way. However, it is interesting to note that this galaxy is not the heaviest element in the local cluster.

Because it is the closest spiral galaxy to us, astronomers use the Andromeda Galaxy to understand the origin and evolution of this type of galaxy.

The Andromeda Galaxy has two very dense nuclei. Not only does the galaxy have a massive star cluster at its center, but it also has at least one massive black hole in its core.

The Andromeda Galaxy has at least two spiral arms, plus a ring of dust. Evidence suggests that this dust ring may have originated from the smaller galaxy M32.

At least 450 globular clusters revolve around the Andromeda Galaxy. Some of them are some of the most populous globular clusters ever seen.

Another important feature of the Andromeda Galaxy is that the Andromeda Galaxy is the farthest object you can see with the naked eye, so to see if you need to be away from light pollution.

The name of this galaxy originates from an area of the sky where the constellation Andromeda is seen.

Features of the Andromeda Galaxy

Name: M31 or NGC224
Model: Spherical
Qatar: 220,000 light years
Distance to the Milky Way: 2.54 million light-years
Mass: 1.230 billion solar masses
Number of stars: one trillion
Constellation: Andromeda
Group: Local group

Black Eye Galaxy

The galaxy was discovered by Edward Pigott in March 1779, and independently by Johann Elert Bode in April of that year, and Charles Messier in 1780. This galaxy has a dark and attractive strip of dust in front of the glowing core of the galaxy, which has led to it being nicknamed the Black Eye or the Evil Eye. The constellation of this galaxy is called “Coma Berenices”.

It was a galaxy

A galaxy is a spiral galaxy 12 million light-years away in the constellation Ursa Major or Ursa Major. The galaxy was discovered by Johann Elert Bode on December 31, 1774.

Wheelchair Galaxy

The Cartwheel Galaxy is a galaxy of lenses and ring-like galaxies located 500 million light-years away in the constellation Sculptor. The name of this galaxy was chosen because of its appearance.

Cigarette Galaxy

The Cigarette Galaxy is a star galaxy about 12 million light-years away in the constellation Ursa Major. The center plate shows the structure in blue and white with a halo of smoky red dust. This red cloud is made up of hydrocarbon dust similar to car exhaust seen by millions of young galaxy stars in space.

Comet Galaxy

It is a spiral galaxy 3.2 billion light-years from Earth. The galaxy is located in the Abell2667 galaxy cluster and the Hubble Space Telescope has been found. This galaxy is located in the constellation of Sculptor.

Infrared Cosmic Galaxy 7

The Cosmos Redshift 7 is known as an alpha-Lyman emitting galaxy with a red transition. Also, the constellation of this galaxy is Sextans.

Galaxy Hogg Object

Hoag’s Object, as it is called, is an unusual galaxy of the type known as the Ring Galaxy. The galaxy was chosen after its discoverer, Arthur Hogg, who discovered it in 1950. Arthur Hogg discovered the galaxy as a planetary nebula or a strange galaxy with eight billion stars. The constellation of this galaxy is Serpens Caput.

Large Magellanic Cloud Galaxy

This galaxy is a satellite galaxy of the Milky Way and is located in the constellation Dorado, also known as Mensa.

Large Magellanic Clouds

About 180,000 light-years away, the LMC, or Large Magellanic Cloud, is a relatively close neighbor to the Milky Way. Without a telescope, the galaxy could be seen from the southern hemisphere.
Small Magellanic Cloud Galaxy

The Little Magellanic Cloud Galaxy is a dwarf galaxy near the Milky Way. The galaxy is one of the closest intergalactic neighbors to the Milky Way and is one of the most distant objects visible to the naked eye. This galaxy is located in the constellation Toucan.

Galaxy Object Mayal

Mayall’s Object is the result of a collision of two galaxies 500 million light-years away in the constellation Ursa Major. The galaxy was discovered by American astronomer Nicholas U. Mayall at the Lake Observatory on March 13, 1940, using a Crossley reflector. This galaxy is also located in the constellation of Ursa Major.

The Milky Way

The Milky Way is essentially a spiral galaxy containing billions of stars, planets, and, of course, black holes; The sun as a star and all the planets around it, including the planet we live on, the planet Earth, are part of the famous Milky Way galaxy. Galileo first observed the optical band of single stars with his telescope in 1610. This galaxy is located in the constellation Sagittarius.

Pinnacle Galaxy

It is a facing spiral galaxy 21 million light-years from Earth. This galaxy is located in the constellation Ursa Major.

Sombrero Galaxy

The Sombrero Galaxy is a spiral galaxy located in the Virgo Constellation.

Sunflower Galaxy

The Sunflower Galaxy is a spiral galaxy in the northern constellation of Venus Reed. The galaxy was first discovered by the French astronomer Pierre Méchain and later confirmed by his colleague Charles Messier on June 14, 1779.

Galaxy Frog

The Frog Baby Galaxy is a closed spiral galaxy located 420 million light-years from Earth in the northern constellation Draco.

Whirlpool Galaxy

The Whirlpool Galaxy is a large spiral galaxy interacting with the active Seyfert 2 active galactic nucleus in the constellation Venetian Reeds and is the first galaxy to be classified as a spiral galaxy.


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