Mars has always had a mystique. It’s one of the easier planets to spot in the night sky, a constant dot of red light moving through the heavens. And now we know for sure that of all the planets, this red, rocky one is the most similar to home. 

 

Here are polar caps and sun-baked deserts, giant volcanoes and mighty canyons. Mars even spins at about the same speed as earth, making a Martian day only about 40 minutes longer than ours. Although it’s further out from the sun and takes twice as long to circle it, the long Martian year has identifiable seasons. And what’s more, our two planets share a common childhood. 

 

“In many ways it’s a sister of the earth. It was formed at roughly the same time, about 4.5 billion years ago, a little change here and there. It also was formed of the same sorts of materials, bombarded by comets and asteroids. So it has the same delivery system we have.”