The reasons are:   1.  After the Big bang, the energy burnt out, the whole universe cooled down gradually :  The truth is, not only Mars was cooling down, even our Earth is cooling down too. ref:  no. 1   2.  Obviously , Mars is further away from the Sun, and also it is  a lot smaller than the Earth, that is why it is cooling down more quickly.       3. Mars has a lot less green house gas . ref:  no. 2    ...

To understand how the core of Mars has formed, we need to look at how the whole solar system did come to be, the inner, rocky planets like Earth and Mars and the outer, gas giants like Jupiter and Saturn.  The picture below does show the whole history of the formation of our galaxy the Milky Way and our solar system.     Here is a picture zoomed in at our solar system as it is now.     And here is the theory of how our planets have formed:   https://youtu.be/0zAAIYMDsTo...

  We learn from our science class during our secondary school that Mars is a red planet, and it is red, because it is full of rusty iron on the surface of the planet. I just watch the follow video, and found it very interesting: https://youtu.be/7koIlNPay-s The iron got rusty because of the rain/water and the oxygen in the air, causing the iron oxidized. But if you look closely at the surface of Mars, you’ll see that it can actually be many different colours. Some regions appear...