Do you know where we are located in this whole universe ? If no then let’s talk about it today.
Our universe contain almost two trillion or two million million galaxies. Some of them are similar to our milky way galaxy but some are quite different. But today first we will discuss WHAT IS GALAXY ?
A Galaxy is a collection of dust , stars , planets , gases and their solar system. There are countless galaxies in the universe and our Milky way galaxy is one of them.
There are also three major categories of galaxies : elliptical , spiral and irregular. So they come in a variety of sizes and shapes.
Milky way is a large spiral galaxy and it is made up of 90% dark matter (which we can not see ) and about 10% is luminious matter (which we can see with our eyes ) and bound together by gravity.
The milky way galaxy probably formed around 13.5 billion years ago (early era of stars and galaxy formation).
Some points :
• Radus – 52,850 light years
• Diameter – 105,700 light years
• Escape Velocity – 550 km/s
• No. Of stars – 100-400 billion
• Age – 13.51 billion years
Milky way galaxy is about 100,000 light years in diameter means it takes 100,000 light years to travel from one edge to other. On the other hand , it about 1000 light years thick.
Our solar system is also a part of milky way galaxy(sun is located on one of the spiral arm) and a supermassive black hole in the center.
The solar syatem is located about 25,000 light years away from the center.
Milky way galaxy is simply a disc with sveral arms of different sizes surrounded by countless stars and a dense bulge in the middle or we can also say a supermassive black hole at the center. The milky way has also some satellite galaxies which are smaller galaxies .
Galactic bulge is the center of the milky way galaxy , usually we call it heart of the milky way galaxy and it is full of dust , stars and gases. Galactic bulge contain large no. Of percent of stars , dust & gases. This is the reason why we can only see a small percentage of the total stars in the galaxy. Lots of dust and gases make that bulge so thick.
As you read above , there is supermassive blackhole at the center of the milky way galaxy , which is billions of times as massive as the sun. According to research , almost every large galaxy has a supermassive black hole at the center.
Until 1953 , Astronomers didn’t know about the spiral structure of milky way galaxy.
The stars in the outer region go at the speed of 220km/sec and takes 250 million years to go once around and the stars closer to the center , the less time they take to orbit just like planet around the sun. This is the phenomenon which responsible for the formation or produces the spiral arms .
The Andromeda galaxy is also a barred spiral galaxy which is 2.5 light years away from earth and also the nearest major galaxy to the milky way galaxy.
The three largest galaxies in the local group are –
• Andromeda Galaxy
• Milky way Galaxy
• Triangulum Galaxy
Andromeda and our Milky way galaxy will collide in about 400 billion years then these two galaxies merge but this event will take billions of years to completion. At the end , they will creat an elliptical shaped galaxy “Milkdromeda” .
The other galaxies are far away from us so that we can only see them through telescope.