Habitable zone

 HABITABLE ZONE

Water is compulsory for life.And water is only presents on that planet which is in the 'Habitable zone'.So what is the 'Habitable zone'?actually this is the constant temperature area from a high energy star,For example: From our solar system 'Habitable zone' is spread about 0.9 astronomical unit to 1.2 astronomical unit.In this are three planets are presents,first Venus,which is far from sun about 10,0000000 km.According to scientists before billions of years Venus was just like Earth (its mass and size are as Earth,there was mountains,oceans and trees but a huge asteroid strike it and its rotation is converted into opposite direction and it becomes the most warm planet of our solar system,scientists also call this 'Heaven star.After Venus the 2nd planet of this zone is Earth,because Earth is in constant temperature area (middle area) here is water, which means here is life.And the 3rd and last planet is far from sun about 226 millions km,it is known as 'Mars' and because it is in our Habitable zone so perhaps there is life because its temperature is adjustable for us and also water is presents,So NASA trying to make there environment better to live.

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