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I'm currently designing a super earth with a surface gravity of 1.5g and a thick oxygen rich atmosphere. Now since the gravity is higher, how exactly would that affect my world? For example:

Geography

  • Could there be mountains as tall as everest there?
  • Since the atmosphere is thicker, would that cause a faster erosion?
  • Would rivers, lakes or waterfalls be affected by the higher gravity?
  • What about Volcanic and seismic activity? Do they get affected by higher gravity?
  • What about the ocean topography? How does it get affected by the force of gravity?

Weather & Climate

  • Since the atmosphere is thicker how would that affect the weather?
  • What would the climate be like?
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Mount Everest approaches the tallest possible mountain. In a 1.5g gravity well mountains would be much lower.

A thicker atmosphere coupled with higher gravity might lead to increased erosion. A key parameter is the rotational speed of the planet. All other beings being equal I would expect it to be greater than Earth due to the increase in mass, so the ground speed at the equator compared to the poles would be greater leading to faster winds.

Rivers would run faster causing more rapid erosion as silt and debris where dragged along at a faster rate.

Tectonic activity would require more energy input to fight the increase in gravity so tension might build more slowly but be released with greater violence. The basic topography of the oceans would probably remain as they are on Earth, except the continental shelves might slope more gradually.

Humans would find such an environment impossible to survive in the long term. The strain on the body over even a short period such as a week would be extreme. Native animals would adapt with stronger shorter more muscular bodies.

Side note: assuming landing on a 1.5g world was possible (maybe) it might well be impossible to leave again. 1g is a massive gravitational well that is very difficult to escape from. The rocket equation has exponential terms and increasing to 1.5g would make escape impossible with conventional chemical rockets.

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  • $\begingroup$ But there is not a solid planet with 1.5 g surface gravity and Earth-like temperatures in our solar system. Such planets could only be found around other stars. So any hypothetical human visitors to that planet would have interstellar travel and presumably more powerful ways to lift off from a planet than chemical rockets. And they probably wouldn't want to visit such a dangerous world anyway unless they had anti gravity technology to reduce the pull of the surface gravity. $\endgroup$
    – M. A. Golding
    Commented Oct 27, 2019 at 15:38
  • $\begingroup$ You've covered all the important stuff, so I won't bother making an answer of my own. Note that river speed probably won't accelerate appreciably, because there's a lot less vertical relief. Tectonic forces require more energy to push up, but find it easier to pull down so it probably balances out. Windspeed might not be higher, but air pressure is so wind forces will certainly be higher for the same speeds. Rotational speed of the earth is strongly tied to the presence of our moon, FWIW. $\endgroup$
    – Starfish Prime
    Commented Oct 27, 2019 at 15:41
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    $\begingroup$ One reason wind speeds are likely to be higher is because the planet is likely to be bigger so air at the equator is moving faster than on Earth and has more energy. The differential between the stationary atmosphere at the poles and the rapidly moving air at the equator is a key driver of the weather $\endgroup$
    – Slarty
    Commented Oct 27, 2019 at 15:58

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