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...
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...
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...
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...
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