11
votes
1answer
144 views

Could any known, living organisms on Earth survive on Mars?

No life has been discovered outside of Earth (yet?), but do we know if anything that would be considered "living" on Earth could conquer Mars? (or maybe Venus?) With the Mars One project on the way, ...
7
votes
1answer
37 views

Why does mars appear to retreat across the sky?

If you plot the movement of mars across the Earth's sky it appears to move back on itself during its orbit. Why does it appear to have a loop shape from Earth?