The planet Mars shares numerous characteristics with our own. Both planets have roughly the same amount of land surface area, sustained polar caps, and both have a similar tilt in their rotational axes, affording each of them strong seasonal variability. Additionally, both planets present strong evidence of having undergone climate change in the past.
At the same time, our two planets are really quite different, and in a number of important ways. For instance, atmospheric pressure on Mars is only a fraction of what it is here on Earth – averaging 7.5 millibars on Mars to just over 1000 here on Earth. The average surface temperature is also lower on Mars, ranking in at a frigid -63 °C compared to Earth’s balmy 14 °C. And while the length of a Martian day is roughly the same as it is here on Earth (24 hours 37 minutes), the length of a Martian year is significantly longer (687 days).
But one big difference is that the gravity on Mars’ surface is much lower than it is here on Earth – 62% lower to be precise. At just 0.38 of the Earth standard, a person who weighs 100 kg on Earth would weigh only 38 kg on Mars.
This difference in surface gravity is due to a number of factors – mass, density, and radius being the foremost. Even though Mars has almost the same land surface area as Earth, it has only half the diameter and less density than Earth – possessing roughly 15% of Earth’s volume and 11% of its mass.