What's Life Like on Mars?

After reading this post by the BBC Chris tweeted "What is gravity like on Mars? How long are Martian days? More info needed!"

Gravity on Mars is a bit more than a third* of that which you experience here on Earth. This means that whatever you weigh here, divide that by three and that's roughly what you'd weigh on Mars. Another, arguably more fun way to think about this is that you could jump about three times higher on Mars than you can here*****. This may also translate, in the long term, to being able to construct buildings that are three times higher than those we can build on Earth**. Olympus Mons, one of Mars's future tourist attractions, is the highest mountain on any planet in our solar system. Earth mountains are generally shorter because the stronger gravity doesn't allow bigger mountains to form.

A Martian day is just shy of 24 hours and 40 minutes long, which means it's pretty similar to our Earthly experiences, except there's more opportunity for a lie-in. With an angular size of nearly 0.4°, the Sun appears slightly smaller and dimmer than it does from Earth, with an area of Martian land receiving a little more than 40% of the energy received by an equivalent patch on Earth. The highest densities found in Mars's atmosphere are comparable to those found in Earth's atmosphere at about the outer limits of where commercial airlines can fly, so it's pretty thin on the ground. This tenuous atmosphere means that temperatures can vary from -143°C  in a polar icecap winter, up to a relatively balmy 35 °C on a summer's day at the equator. If you're planning a trip, I'd advise checking out MarsWeather.com before you set out in order to avoid disappointment.

A comparison of the eccentricities of the orbits of Earth and Mars
By Areong, via Wikimedia Commons
Of course, weather changes with the seasons so it might be useful to think about what happens with those on Mars. Seasons on Earth are affected by two things, mainly: axial tilt and orbital eccentricity. Mars's axial tilt is close to that of Earth, so it has a readily identifiable set of spring, summer, autumn and winter seasons. Mars's orbit is pretty eccentric, though - with an eccentricity of 0.09***, the only planet more eccentric in our solar system is Mercury. Mars's greater distance from the sun means that the seasons are longer than on Earth, and its eccentricity means that their relative lengths differ more than they do here****.

Another thing to consider if you're weighing up the merits of relocating is that Mars doesn't have much of a magnetic field to speak of. This might not sound important at first, but it's what, here on Earth, protects us from the continual outpouring of charged particles from the sun - the radioactive solar wind. It is thought that over time Mars has lost much of its atmosphere due to its lower level of protection from the sun's unseen influence.

Go to it, good luck, and don't forget your sunscreen! Or heavy duty winterwear. Or biodomes.

* It's actually almost 38% of Earth gravity, so I'm simplifying here.
** What I really mean here is that it'll be easier to build taller structures on Mars than on Earth.
*** If an orbit has an eccentricity of 0, it's a perfect circle, with higher values referring to ever-longer ellipses. If it has an eccentricity of 1 it's a parabola, and eccentricity is greater than 1 for hyperbolic orbits.
**** We see these differences on Earth - Southern hemisphere summers tend to be longer and hotter than Northern hemisphere summers due to Earth's orbit's eccentricity.
***** As an aside, it's possible that if we were to establish a colony on a world with a thick enough atmosphere and low enough gravity we'd be able to don a pair of wing-sleeves and fly like birds under our own arm-power. How cool is that?


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