Ever since the Big Bang started, our Universe has been expanding. The birth and death of primitive stars gave rise to the formation of galaxies, stars, planets and other heavenly bodies. Our galaxy, the Milky way galaxy, is about 13.6 Billion years old. There are approximately 100-400 billion stars in the Milky Way, such as our closest star, the Sun. Every star has its own planetary system. The sun's planetary system is known as the solar system.
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About five billion years ago. Some clouds of space dust from our Milky Way galaxy began condensing under its gravity, and about 4.6 billion years ago it exploded through nuclear fusion and formed a star, our Sun. It drew 99.8% of our solar system. In this article, we will learn more about our solar system.
The sun and eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune) with some other celestial bodies called satellites, meteoroids, comets and asteroids.
The sun is the centre of the solar system. It is so huge and made up of extremely hot gases and contains 99.86% of the total mass of the Solar System. It has the gravitational force that holds the solar system together. It is about 150 million km away from the us.
All the eight planets of the solar system move around the sun in fixed paths. These paths are elongated. They are called orbits. Mercury is nearest to the sun. It takes only about 88 days to complete one round along its orbit. Venus is considered ‘Earth’s-twin’ because its size and shape are very similar to that of the earth. Until recently (August 2006), Pluto was also considered a planet. However, in a meeting of the International Astronomical Union, a decision was taken that Pluto, like other celestial objects (Ceres, 2003 UB313) discovered in the recent past, maybe called a dwarf planet.
The Earth
The earth is the third-nearest planet to the sun. In size, it is the fifth-largest planet. It is slightly flattened at the poles. That is why its shape is described as a Geoid. Geoid means an earthlike shape.
Conditions favourable for supporting life are probably found only on the earth. The earth is neither too hot nor too cold. It has water and air, which are absolutely essential for our survival. The air has life-supporting gases like oxygen. For these reasons, the earth is a unique planet in the solar system. From outer space, the earth appears blue because its two-thirds surface is covered by water. It is, therefore, called a blue planet.
The Moon
Our earth has only one satellite, that is, the moon. Its diameter is only one-quarter that of the earth. It appears so big because it is nearer to our planet than other celestial bodies. It is about 3,84,400 km away from us. Now you can compare the distance of the earth from the sun and that of the moon. The moon moves around the earth in about 27 days. It takes the same time to complete one spin. As a result, only one side of the moon is visible to us on the earth. The moon does not have conditions favourable for life. It has mountains, plains, and depressions on its surface. These cast shadows on the moon’s surface. Look at the full moon and observe those shadows.
Apart from the stars, planets and satellites, numerous tiny bodies also move around the sun. These bodies are called asteroids. They are found between the orbits of Mars and Jupiter. Scientists are of the view that asteroids are part of a planet that exploded many years back.
The small pieces of rocks which move around the sun are called meteoroids. Sometimes these meteoroids come near the earth and tend to drop upon it. During this process, due to friction with the air, they get heated up and burn. It causes a flash of light. Occasionally, without being completely burnt, a meteor falls on the earth and creates a hollow. Do you see whitish broadband, as a white glowing path across the sky on a clear starry night? It is a cluster of millions of stars. This band is the Milky Way. Our solar system is a part of this galaxy. In ancient India, it was imagined to be a river of light flowing in the sky. Thus, it was named Akash Ganga. A galaxy is a massive system of billions of stars and clouds of dust and gases. There are millions of such galaxies that make the Universe. It is difficult to imagine how big the universe is. Scientists are still trying to find out more and more about it. We are not certain about its size, but we know that all of us – you and I, belong to this universe.
A satellite is a celestial body that moves around the planets in the same way as the planets move around the sun. A satellite is an artificial body. It is designed by scientists to gather information about the universe or for communication. It is carried by rocket and placed in orbit around the earth. Some Indian satellites in space are INSAT, IRS, EDU SAT, etc.
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History
About five billion years ago. Some clouds of space dust from our Milky Way galaxy began condensing under its gravity, and about 4.6 billion years ago it exploded through nuclear fusion and formed a star, our Sun. It drew 99.8% of our solar system. In this article, we will learn more about our solar system.
What is a SOLAR SYSTEM?
The sun and eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune) with some other celestial bodies called satellites, meteoroids, comets and asteroids.
The Sun
The sun is the centre of the solar system. It is so huge and made up of extremely hot gases and contains 99.86% of the total mass of the Solar System. It has the gravitational force that holds the solar system together. It is about 150 million km away from the us.
Planets
All the eight planets of the solar system move around the sun in fixed paths. These paths are elongated. They are called orbits. Mercury is nearest to the sun. It takes only about 88 days to complete one round along its orbit. Venus is considered ‘Earth’s-twin’ because its size and shape are very similar to that of the earth. Until recently (August 2006), Pluto was also considered a planet. However, in a meeting of the International Astronomical Union, a decision was taken that Pluto, like other celestial objects (Ceres, 2003 UB313) discovered in the recent past, maybe called a dwarf planet.
The Earth
The earth is the third-nearest planet to the sun. In size, it is the fifth-largest planet. It is slightly flattened at the poles. That is why its shape is described as a Geoid. Geoid means an earthlike shape.
Conditions favourable for supporting life are probably found only on the earth. The earth is neither too hot nor too cold. It has water and air, which are absolutely essential for our survival. The air has life-supporting gases like oxygen. For these reasons, the earth is a unique planet in the solar system. From outer space, the earth appears blue because its two-thirds surface is covered by water. It is, therefore, called a blue planet.
The Moon
Our earth has only one satellite, that is, the moon. Its diameter is only one-quarter that of the earth. It appears so big because it is nearer to our planet than other celestial bodies. It is about 3,84,400 km away from us. Now you can compare the distance of the earth from the sun and that of the moon. The moon moves around the earth in about 27 days. It takes the same time to complete one spin. As a result, only one side of the moon is visible to us on the earth. The moon does not have conditions favourable for life. It has mountains, plains, and depressions on its surface. These cast shadows on the moon’s surface. Look at the full moon and observe those shadows.
Asteroids
Apart from the stars, planets and satellites, numerous tiny bodies also move around the sun. These bodies are called asteroids. They are found between the orbits of Mars and Jupiter. Scientists are of the view that asteroids are part of a planet that exploded many years back.
Meteoroids
The small pieces of rocks which move around the sun are called meteoroids. Sometimes these meteoroids come near the earth and tend to drop upon it. During this process, due to friction with the air, they get heated up and burn. It causes a flash of light. Occasionally, without being completely burnt, a meteor falls on the earth and creates a hollow. Do you see whitish broadband, as a white glowing path across the sky on a clear starry night? It is a cluster of millions of stars. This band is the Milky Way. Our solar system is a part of this galaxy. In ancient India, it was imagined to be a river of light flowing in the sky. Thus, it was named Akash Ganga. A galaxy is a massive system of billions of stars and clouds of dust and gases. There are millions of such galaxies that make the Universe. It is difficult to imagine how big the universe is. Scientists are still trying to find out more and more about it. We are not certain about its size, but we know that all of us – you and I, belong to this universe.
Satellite
A satellite is a celestial body that moves around the planets in the same way as the planets move around the sun. A satellite is an artificial body. It is designed by scientists to gather information about the universe or for communication. It is carried by rocket and placed in orbit around the earth. Some Indian satellites in space are INSAT, IRS, EDU SAT, etc.
How much time the sunlight takes to reach us?
The sunlight takes an average of 8 minutes and 20 seconds to travel to the Earth from the surface of the Sun. The Sun is so far and the light travels at the speed of about 300,000 km per second. But, do you know this light is generated by nuclear fusion deep in the sun's fiery core and it takes thousands to millions of years to reach the surface of the sun.
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General knowledge