Astronomy

What is Astronomy?

Let us answer this question and make you know it! Note: This blog comes with links to wikipedia refernces for you to study in more depth about the topics. Astronomy is the study of celestial bodies and the cosmos. The universe is a the place where this all exists. In astronomy, we study about the existense of these objects. Which includes the questions 'What they are? How they are formed? How they behave? What are their properties? etc-. In study of the cosmos, we study about some concepts which seem abstract, but are real! These concepts lay the foundation of our understanding. Astronomy comes combined with another term called Astrophysics, which is the study ofcelestial bodies and learning how they are born, live and die. Also, as the term says, "Astro-Physics", it aims to understand the universe from a more physics point of view. It adds a lot of Mathematical explanations, which better define objects than only astronomy by itself. They both come under the category of space science.

Now let us learn the basics of Astronomy so that we can dive deeper into the subject of space science

What are Stars?

For the basic defination, Stars are massive huge balls of plasma which release heat and light due to the proccess of Nucleur Fusion which uses Hydrogen as its main feul. Nucleur Fusion is a proccess in which due to immense pressure and heat, two atomic nucleui fuse to form one larger nucleus and release energy in the form of heat. Stars are made of mainly hydrogen and helium. Stars also being very massive, exert a huge gravitational pull onto objects near them. In a Star, there are mainly two major forces. Nucleur Fusion exerting an outward force and gravity pushing everything inside. Due to the balancing of these two forces, a Star is able to exist stabally. The next question is,

How they are formed?

In space, when a large amount gas and dust collects together, known as a nebula, its own gravitational pull pulls it inwards, making it denser, more massive and hotter. When enough of this collects and heats up, it takes the shape of a sphere and is now called a PROTOSTAR. A protostar is still gathering more mass, but once its core temparature exceeds 10 million kelvin, it starts nucleur fusion and releases heat and light. It is now called a main sequence star.

Now, Let us undertand some more properties of these Stars. There are several different type of Stars which is determined dependning upon the Mass of the Star. The Image below shows the classification of stars upon their Mass which also determines their colour:

• Low Mass Stars: Stars ranging from M to K. They include Red Dwarfs which burn upto 10 trillion years! They die by burning fuel and turning into a white dwarf.
• Average Mass Stars: Stars raning from G to F. They include Yellow Dwarf Stars which burn for a few billion years, like our Sun. After they run out of fuel, they expand to ten time their size, turning into red gaints. They shed the outer layers creating a steller nebula, and the core becomes a white dwarf.
• High Mass Stars: Ranging from A to O. They include Red Gaints, White Gaints and Blue Gaint stars. They burn for only a few hundread million years. After they run out of fuel, they explode into a supernova. Depending on their size, they turn into a nuetron star or black holes.

What are Galaxies?

Now, lets talk about where do Stars exist. Any idea? Of course they are here in space, but where in space? When our universe was born with a big bang, due to gravity, large amounts of gas collected around some common points of gravity. Inside these massive collections of gas, small points became a little more massive than other, pulling gas and dust, and helping in the making of stars. The massive collection of gas, are Galaxies.
Every Galaxy has one thing in common, they have a black hole in their centre, around which all the Stars orbit. Yes! Stars also do orbit the centres of galaxy, known as the galactic centre. The entire galactic centre ususally has a dense concentration of Stars which were created long ago. Just like stars, galaxies also have types.

Spiral Galaxy

Barred-Spiral Galaxy

Elleptical Galaxy

Irregular Galaxy

Lets learn a little more about galaxies now. Galaxies dont necessarly just float around, some of them too orbit larger ones! Even our milky way has got one galaxy orbitting it. Quasars are also called

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