Space is black , why ?

Why is the space black 

Why is space black ? Well its a question much harder than expected. Many researchers and scientists have worked throughout the time to find an answer but have not reached to any solid conclusion. 

Well to explain this let's try out a simple question why is the day sky on earth blue ? Well the daytime sky is blue because light from nearby source which is sun hits molecules on the earth's atmosphere and gets scattered hence giving its colour, for darkness of night we say that the side facing opposite to sun has no light to scatter hence giving the colour of space which is black. If you were on the moon the night and the day sky both remain black due to absence of atmosphere , as is evident from apollo footages. 

Now on to the harder part - if the universe is full of stars, why doesn't the light from all of them add up to make the whole sky bright all the time? It turns out that if the universe was infinitely large and infinitely old, then we would expect the night sky to be bright from the light of all those stars. Every direction you looked in space you would be looking at a star. Yet we know from experience that space is black! This paradox is known as Olbers' Paradox. It is a paradox because of the apparent contradiction between our expectation that the night sky be bright and our experience that it is black.

Many different explanations have been put forward to resolve Olbers' Paradox. The best solution at present is that the universe is not infinitely old; it is somewhere around 15 billion years old. That means we can only see objects as far away as the distance light can travel in 15 billion years. The light from stars farther away than that has not yet had time to reach us and so can't contribute to making the sky bright.


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