Astronomy Notes for Class 11-12

Explain the mystery of the origin of our universe

From the beginning of recorded history, it is seen humans expressed different theoretical notions about the origin and fate of our universe. At present, this branch of science is called cosmology.

The branch of physics which discusses the nature, source, and evaluation of the universe is called cosmology.

The theory related to the creation of the universe is given below.

1) Big-Bang Theory

2) Expanding Universe Theory

3) Pulsating Theory

4) Steady State Theory

There are three types of fundamental particles-

Field particles: Field particles consist of the main photon, boson, and gravitation. These particles create electromagnetic force, weak nuclear force, and gravitational force.

Lepton particles: These particles can not take part in the electromagnetic and weak nuclear process.

Hadron particles: The particles which can participate in strong nuclear electromagnetic, and weak nuclear interaction are called Hadron particles. Hadron particles are of two types - Mesion, Baryon. Spin of meson is zero but spin.

There are many particles whose mass, spin are equal to a particle but change, baryon number, lepton number are equal to other particle but opposite. These are called antiparticles.

God Particle

A theoretical force field called Higg's Boson field is spreader in the universe. A massless particle gradually gain mass when it enters into the field. As a result, it's velocity decreases mass converts into particle through this field. HIgg's field can not create mass it can only transfer to a particle through Higg's Boson. These Higg's Boson are known as God's particles.


Quarks are very tiny atomic particles by which proton and neutrons are formed. Scientist Gelman named these very tiny atomic particle as quarks. Scientist have discovered six different types of Quarks till now. Quarks have their own quantum numbers. 

Explain the end of the universe in accordance with physics

Explain the main objects of the universe and different phenomenon

Explain the principle of different astronomical tools

Big Bang

The expansion of the universe indicates an initial point from where it is expanding. About 15 hundred crore years ago it started from space-time singularity. 

In the beginning, it was infinitely dense and infinitely hot and it expands after the big bang in all directions. After starting to expand it becomes cooler and goes through some intermediate changes.

If a star has enough mass and density then its gravity field will be so strong that no light can emit from that star. Before traveling away from the star, the gravitational field will be so strong that no light can emit from that star. 

Before traveling away from the star, the gravitational pull will take that back. Scientist Michell thought that this type of star can be in huge amounts. We can not see those stars because no light emits from them. We can only feel the gravitational pull of that object. These objects are called black holes.

Event Horizon

If Rs is the radius of a rotational or irrotational spherical object then no light can escape the surface of the sphere and the object acts as a black hole. In this case, any object within the radius Rs will be locked inside the black hole and can not escape. The surface with the radius Rs around the black hole is called an event horizon.

Radio Telescope

To study radio waves emitting from stars, galaxies, quasars, and other astronomical objects radio telescope is used.

Optical Telescope

To observe objects far away from us, the machine used is called an optical telescope.

Gamma Ray

Three types of rays are emitted from radioactive material. The ray which is not affected by the magnetic field and travels straight as an electromagnetic wave is called a gamma ray.


If high-speed electrons hit a metal then an unknown ray of high penetrating power radiation is emitted. This radiation is called an x-ray.

Artificial Satellite

A man-made spacecraft at a definite height from the ground can orbit an earth-like moon. This spacecraft is called an artificial satellite.

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