Space Science

Father of space science is Konstantine Tsialkovsky from Russia
Galaxies are formations of innumerable stars grouped together by gravitational force.
Andromeda galaxy is similar to the Milky Way
Stars are formed by gravitational contraction from vast clouds of (gas and dust). Star is a celestial body which has its own light.
Comets are stars with tails. Comet is a Greek word meaning long haired star. The head of the comet is star; the long hair is the tail which resembles like hair.
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Cosmic rays:
It consists of atomic nuclei that reach the earth from outer space, which is nothing but radiating energy.
Satellite is a secondary body that revolves round the planet.
Planet is also a celestial body which revolves round the sun in elliptical orbit.
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Solar System
The sun, the planets around the sun and the satellites around the planets are jointly called the solar system.
The sun has a force of attraction (gravitational force) and hence all the planets in the solar system revolve in a regulated path.
Diameter of the Sun =1392000 K.M.
Weight of the sun =33 lakhs times more than that of the earth.
Temperature at the core of the Sun: Around 15 million degree Kelvin
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Planets
Totally there are 9 planets,namely Mercury,Venus,Earth,Mars,Jupiter,Saturn,Uranus,Neptune and Pluto.