The crossing star theory (Chamberlain and Moulton 1905) The assumptions of the crossing star theory assumed that the solar system was originally the Sun, A huge star approached to the Sun, This star attracted...
The solar system the solar system consists of the Sun ( star ) , Eight planets ( revolving around the Sun in fixed orbits ) , the comets , the asteroids and the moons...
Big Bang is a massive explosion happened, since 15000 million years, resulted in it all the forms of matter, energy and time, It is the expansion of the universe and merging of atomic particles...
The Universe The universe is the wide and extended space that contains all the galaxies , the stars , the planets , the moons , the living organisms , and everything , The universe...
The weight The reason of object’s falling downward the Earth is a type of force called the weight (the gravitational force), and you can feel this force when you carry an object or try...
The global warming phenomenon The global warming is caused by the greenhouse effect, It is the continuous increase in the average temperature of the Earth’s near-surface air, The increase of the concentration of carbon...
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