our solar system class 11
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Answer:
Class 11 – Chapter 2 – Origin and Evolution of Earth
Part 2 of 3 – Formation of Stars, Planets and Our solar system
Formation of stars:
Uneven distribution of matter in the universe resulted in varied gravitational forces.
A galaxy was formed by accumulation of hydrogen gas in the form of nebula. As nebula grew, it developed localized gas lumps which got converted into various stars. A galaxy contains several stars.
The distance among the mass bodies in universe are measured in Light years.
Formation of planets:
A core to the gas cloud and rotating disc of gas are created due to the gravitational force within the gas lumps.
The rotating gas gets condensed into small objects. These small objects stick together to form Planetesimals.
These planetesimals accrete and stick together to form larger bodies called Planets.
Our solar system:
Our solar system had nine planets with sun as a star.
It had formed 5-5.6 billion years ago.
Among the nine planets the first four planets are Inner planets, which are also called rocky or terrestrial planets. The rest of planets are outer planets and are called gaseous or Jovian planets.
The rocky planets cannot hold the gases hence it blew off due to the sun’s gravity. But the gaseous planets cannot strip off their gases hence holds large amount of gases resulted in larger radius and low density.
Moon is the earth’s only natural satellite that revolves around the earth. Moon is formed 4.4 billion years ago due to ‘Big Splat’. Shortly after formation of earth, huge object collided with Earth and blasted a large part of earth into space