What are galaxies and what are their types

 
We usually think that all the stars in the universe are scattered at random. No! Instead they are well grouped together. Galaxy is a cluster of several million stars, some gases and space dust. Now you know, an invisible force (also called a bridge) that attracts any two objects found in the universe. All the stars in the galaxy are held together as a large group by the force of each other.


https://cdn.pixabay.com/photo/2016/06/23/16/07/background-1475670_960_720.jpg
Source


You have probably heard that our sun is located in the Milky Way. But what is this galaxy after all? The simple answer is that a galaxy is a collection of stars organized by their mutual galaxy. In other words, all the stars in the galaxy are held together by the gravity of all other stars (as well as invisible, mysterious dark matter).
 

 
 

What are galaxies?

The galaxies are a cluster of millions to trillions of stars, which revolve around their normal center of gravity. They also include interstellar gas and dust.

Galaxies are huge space systems made up of dust, gas, and countless stars.

Galaxies have a large number of star systems, clusters, and interstellar clouds.

It is believed that galaxies were formed billions of years ago due to a large cosmic explosion. Just a few milli-seconds after the massive explosion, gases began to burst and compress under gravity, and galaxies were formed.

Almost all stars belong to a cluster of galaxies.


https://cdn.pixabay.com/photo/2015/11/15/08/15/universe-1044107_960_720.jpg
Source


The Milky Way is so large that we cannot measure it in kilometers or miles. So we use another measure called Light Year to measure it. What is a Light Year now?
 
We know the Milky Way very well, so let's take a good example of the Milky Way. Milky Way is a spiral galaxy. It has a bright central core with a high density of stars, and then a flattened disk around it - like a spinning record.

The two spiral arms are outside the core, and then spiral outward like a pinwheel on the outer edges of the galaxy. Milky Way consists of 100,000 light-year crossings, and can contain 200–400 billion stars.

But the stars you can see are only a small fraction of the entire galaxy. It is also surrounded by huge halos of dark matter. This material is invisible, and does not interact with regular matter or radiate any kind of radiation that we can detect. But astronomers can measure its effect because it exerts gravitational forces on other matter.

In fact, the Milky Way is mostly composed of dark matter. The stars have about 580 billion solar masses, and the dark matter can be 6 trillion solar masses.

 

https://cdn.pixabay.com/photo/2019/08/19/11/59/milky-way-4416194_960_720.jpg
Source

Different Shapes and Sizes of Galaxies

There are also many shapes and sizes of galaxies.

We have galaxies of different sizes. The most common shape is an elliptical galaxy, then we have a disk-shaped galaxy called the Spiralacryphas and finally the galaxies are called irregular galaxies with unusual or regular shapes. Less than one billion stars in galaxies are considered as small galaxies.

 

1) Spiral Galaxies

Our galaxy is a spiral galaxy. The ellipse (egg shape) is another common shape for a galaxy such as M87. How the stars are collected together in galaxies, galaxies are collected in clusters. The largest structure galaxies in the universe are a super cluster, consisting of millions of galaxies and therefore trillions of stars.

Some scientists say that the universe has more stars than sand particles on every beach in the world. Wow !

The most beautiful galaxies are spiral galaxies. Its spiral arms surround the waves that create new stars. A galaxy of this size consists of a flat disk with a bulge at the center and spiral arm. This flat shape disk contains stars, planets, gases, and dust particles that revolve around its center. It seems like a cosmic pinwheel.

For example:- Our Galaxy
 

2) Elliptical Galaxies

As the name suggests, this shape is usually round. But it is tighter on one axis than the other. They contain about one trillion stars but very little dust. These stars are usually old or developed stars. Elliptical galaxies orbit stars in random directions with a common center. The largest known galaxies are of this size.

For example: - Maffei 1

 


Source

3) Irregular Galaxies

Galaxies that are not spiral or elliptical are known as irregular galaxies. These galaxies appear to have no shape and no specific appearance. This is because they are subject to gravitational effects close to galaxies.

For example: - Sextans A

 

Earth is located in which galaxy?

We are part of a spiral galaxy called the Milky Way. It has our solar system. The name Milky Way is derived from its appearance. It appears like a band glowing with a "milky" color in the night sky.

The open eye cannot separate individual stars. It is called Milky Way because when it is seen on a clear night it seems that milk is spread all over the sky. The Milky Way consists of 200 billion stars including our Sun.

Our galaxy is spiral in shape and has three main components: -

• A disk in which our solar system is present
• A central bulge.
• A hello

The galaxies often crash at each other. Even our own galaxy passes through others.

However, you do not have to worry about it. The galaxies can safely pass through each other. The stars are so far away that their chances of collision are very low.

Close to our galaxy, Andromeda and Triangulum are two galaxies, both of which are spiral galaxies.

 

The Milky Way

 

Our Milky Way is a blocked spiral galaxy with more than 100 billion stars. Spiral disks of stars, gas, and dust are about 100,000 light-years and 2,000 light-years thick — thicker than pancakes.


https://cdn.pixabay.com/photo/2015/10/12/14/59/milky-way-984050_960_720.jpg
Source


On the posterior edge of this subtle spiral arm revolves within the disc. It takes the Sun about 220 million years to complete one revolution of the Milky Way, and about 20 revolutions have been completed since the birth of the Solar System.

The Milky Way lives in the neighborhood of a few dozen galaxies called the Galaxy Local Group. They range in size from dwarf galaxies to large Andromeda galaxies. Over time, these galaxies communicate with each other, changing their speed and size. The long-term evolution of a galaxy is influenced by part of the cluster. The Milky Way and the Andromeda Galaxy, our closest spiral neighbors, are moving towards each other. In about five billion years, they can collide and merge together.

---

Thanks for being with me, Have a nice day.