Question

Mars was perhaps once a lot like Earth. Why is this no longer the case?

a) The Sun has cooled down.
b) The CO2 in Mars' atmosphere has leaked away into space.
c) A massive impact on Mars had catastrophic consequences.
d) Mars has undergone a runaway greenhouse effect.
e) Mars does not have volcanoes, and so has cooled down.

Answer 1

Mars was once like Earth, but its atmosphere and water gradually disappeared, leading to its current cold and dry state.

Step-by-step explanation:

Mars was once a lot like Earth, with a thick atmosphere and abundant liquid water. However, several factors have caused Mars to become the cold and dry planet we see today. One of these factors is the loss of its atmosphere, which allowed most of the water on Mars to freeze out, reducing its ability to retain heat. This loss of atmosphere likely occurred within a billion years after Mars formed.

In addition to the loss of atmosphere, Mars' smaller size and lower gravity compared to Earth and Venus made it easier for atmospheric gases to escape into space. The continuous escape of gases further contributed to the cooling of Mars over time.

Overall, the combination of these factors, including the loss of atmosphere and the freezing of water, has led to the current cold and dry conditions on Mars.