Often when you read the subject of geography, you get to know about the universe, today we are going to tell you about all the things that will be useful in the upcoming exam, so definitely read them well. Questions are often asked from this topic concerned in the exam, so it is very important.
Learn About The Universe
• The universe is infinite in which planets, satellites, stars, galaxies, meteorites, celestial dust-particles are included.
• The combined form of matter and energy is called the universe. Our Earth is a member of the Solar System. Our solar system is a minor part of our universe.
• The entire universe is empty except for tiny clumps of energy and matter.
• The universe has neither a focal point nor a starting point.
Concept of Universe
• The universe is a very detailed concept.
• There is black, deep and infinite space in the universe.
• Stars are visible in the universe either they release energy or they are visible due to refraction of celestial body light.
♦ Big Bang Theory
• The credit for this theory goes to a scientist named Edwin Hubble who said that the universe is constantly expanding, which means that the universe must have been denser. Although no one knows what was in it before, Hawking believed the creation of the universe to be a spontaneous event. The famous scientist Isaac Newton believed that there must be some creator of this universe, otherwise such a complex creation could not be born.
• The Big Bang theory is the most reliable theory about the universe. According to the Big Bang theory, the zero-sized universe was very hot. Because of this it exploded and it spread into innumerable particles. Since then it has been spreading continuously till now.
♦ Galaxy
• It is a huge bundle of stars. There are 10,000 million galaxies in space. There are 100,000 million stars in each galaxy. Apart from stars, dust and gases are also found in the galaxy.
• There are about 100 billion galaxies in the universe. A group of galaxies is called a supercluster.
• Our galaxy is a part of the supercluster named Saraswati Super Cluster.
• Earth is a part of the galaxy called Milky way.
• Stars are formed as a result of a concentration of matter in this vast universe. A large group of these stars together form the galaxy.
• The Milky Way was formed from a group of fissile materials after the Big Bang explosion.
• The galaxy contains a vast number of stars, which are similar to the basic building units of the universe. A supercluster consists of 40 to 43 clusters, with about 1000 to 10000 galaxies in a single cluster.
• Milky Way / Mandakini / Milk Mekhela – Sun, Earth and our solar system are part of a supercluster called Laniakea Supercluster.
• There are about 1011 galaxies in the universe and the same number of stars are present in each galaxy.
• There are about 1011×1011=1022 total stars in the universe.
Major Galaxies
(1) Lime Alpha Blocks
• It is the largest galaxy in the universe.
(2) Andromeda-
• The closest galaxy to our solar system/galaxy is.
(3) Mandakini –
• Our solar system is located in this galaxy.
• This galaxy is also called Milk Mekhela Galaxy.
• The shape of this galaxy is spiral.
Nebula
• A nebula is a stellar cloud consisting of particles of gas and dust.
• Due to the different properties of the nebula, it is determined on the basis of its composition and environment.
Orion Nebula
• This is the brightest part of our Galaxy. It is kind of a bunch of stars.
Pleiades Nebula-
• It is a type of reflection nebula, which shines with the reflected light of nearby large stars.
Barnard 68-
• It is a dark nebula that is visible at the same time, with a huge bright surface behind it.
Making of Stars
• The distribution of energy and matter was not uniform in the early universe. The initial variation in density led to variations in gravitational forces, resulting in the accumulation of matter. This gathering became the basis for the evolution of galaxies. A galaxy is a group of innumerable stars.
• Galaxies are so large that their distance is measured in thousands of light years. The diameter of a single galaxy can be between 80 thousand and 1 lakh 50 thousand light years. The formation of a galaxy begins with the accumulation of a giant cloud made of hydrogen gas called a nebula. Clumps of gas developed in this growing nebula. These swarms grew and became dense gaseous bodies, from which the formation of stars started. It is believed that stars formed about 5 to 6 billion years ago.
| Light YearLight year is not a measure of time but a measure of distance. The speed of light is 3 lakh km per second. It is worth considering that the distance that light will travel in a year will be one light year. This is equal to 9.46 trillion km. The average distance of the Earth and the Sun is 149.59 million kilometers. In terms of light-years, it can be quantified to 1.58 × 10^-5 light-years and it takes 8 minutes and 20 seconds for sunlight to reach earth. |
Life cycle of Stars
• The life span of stars is extremely long.
• The life cycle of a star has the following stages.
Due to the gravitational force of gases and dust particles present in the universe, the nuclear fusion reaction starts in the center of the galaxy and due to the conversion of hydrogen into helium, new stars are formed, that is, these are called stellar nurseries.
• The final life cycle of a star is considered to be a black hole because the star dies after an explosion.
Chandrasekhar limit-
• If the mass of a star is 1.44 times the mass of the Sun, it becomes a black hole.
• Chandrashekhar had propounded about the life stage theory of white dwarf star in 1930.
Black Hole –
• This is the center of the star which is not visible due to the refraction of light. But due to the emission of energy in the form of X rays, it makes its presence felt. (X rays were discovered by Routzen)
Proto star-
• Formation of this star occurs when the cloud of hydrogen in the galaxy is large, then the gaseous bodies start shrinking due to the effect of gravity, which is considered to be the initial stage of star birth.
Full Star-
• As the star shrinks, the number of collisions of atoms in the gas cloud increases due to which hydrogen starts to convert into helium.
Red Demon Star
• The energy distribution intensity decreases due to the conversion of hydrogen in the left shell of the star to helium and the color changes to red. This stage is called red demon star.
• If the mass of a star is less than the mass of the Sun, then it changes from red giant to white dwarf and finally into black dwarf.
Supernova-
• A supernova is formed by the explosion of the Red Demon Star.
• If the mass of a star becomes many times more than the mass of the Sun, then the center of the star collapses due to gravity in the middle layers of the star and the energy released from it completely destroys the upper layer of the star and causes a terrible explosion. This phenomenon is called supernova explosion.
• After the supernova explosion, that star splits into a neutron star and a white dwarf star and after that the star goes into the Black Hole.
• Supernova is an exploding state of a star.
Neutron star-
• A star made up of neutrons orbiting at high speed is called a neutron star.
• The density of this star is high.
• This star emits very strong radio waves.
• This star is also called Pulsar.
Constellations-
• Various groups of stars are also called constellations.
• They are located in the sky around the Earth and are visible in the night time. Their number is considered to be 27.
Pole Star
• It is always visible in the north direction.
• It is also called Polestar.
• The literal meaning of Dhruva is unshakable or stable.
• Different groups of stars are called constellations.
• The constellation of stars is known by different names in different countries.
• The group of seven stars visible in the sky in India is called Saptarshi Mandal.
• In India, a group of four strings is called a charpai.
• These stars are called sausages or hand cauldrons in France.
• Farm plow in Britain, in Greece it is part of Small Bear Barley Arsamager / Great Bear.
• Imaginary stories/traditional tales displayed by mankind about stars are called myths.
The formation of planets
• The following stages of planetary development are considered-
1. Stars are bundles of gas inside a nebula. Due to the force of gravity in these intertwined clusters, the core was formed in the gaseous cloud and a rotating plate of gas and dust developed around this gaseous core.
2. In the next stage the condensation of the gaseous cloud started and the material covering the core developed into small balls. These small spheres evolved into planetesimals by the process of cohesion (mutual attraction between molecules) and by the process of collision they began to form larger bodies and they were joined together as a result of the force of gravity. The larger number of smaller bodies are the planets.
3. In the final stage, some large bodies formed in the form of planets when these many small planetesimals coalesced.
Celestial Body-
• The stars, meteors, planets, satellites, comets etc. spread in the sky, including our Earth, Sun and Moon, are called celestial bodies.
• The most famous tail star is Halley. It appears after 76 years. It was seen in 1986. This star is very attractive and strange.
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