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What would life probably look like if there was low gravity?

What would life probably look like if there was low gravity?


Image by Tyler Smith[1] .

Low gravity planets would be smaller than Earth. The ones with gravity only a little lower than on Earth might be similar in size but just simply less dense, however.

  • They would lose their internal heat faster, which means that they would not be able to maintain a liquid core that generates a magnetosphere and which protects life from harmful radiation from space.
  • Rapidly cooling small planets would also be less likely to have continental drift for long.
  • They would be less likely to hold on to a thick atmosphere in the habitable zone where solar winds are strong. On further away orbits, where solar winds are weaker, a thicker atmosphere might survive but on such orbits, planets would need a different chemistry for life than on Earth because such planets would have a much lower overall surface temperature.
  • Such planets would have taller mountain ranges because the differences between the tallest and the deepest points on the surface would be wider at weaker gravity.

Some of the problems of small planets can be fixed if they were moons of larger gas giant planets. They would get protection from the magnetosphere of their host planet. It would be good if they had their own magnetosphere too so that they are protected from the magnetosphere of the gas planet, which can strip them of atmospheres due to sputtering, which is a process in which atoms are ejected because of bombardment with energetic particles. In our system, the Ganymede moon of Jupiter is thought to possess its own, weak magnetosphere, while the Titan moon of Saturn maintains its thick atmosphere because its composition is more resistant to sputtering.

Very small moons and planets, that have a subsurface ocean, can be habitable to simple, unicellular life.

It’s not likely that life would have time to evolve into complex Earth-like surface-dwelling forms on smaller worlds because they are not thought to be habitable for long enough on the surface due to loss of atmosphere, loss of oceans and loss of liquid core that generates magnetosphere.

On planets that are only a little smaller than Earth or on planets where life evolved from different chemistry so that it has different requirements and is not held back by all the issues that smaller worlds come with, complex forms of life could have these features:

  • They could grow to bigger sizes than on Earth because it’s easier to move around in weaker gravity.
  • On Earth, bigger organisms tend to have longer life spans. It might be the same on such a planet.
  • On planets with thinner atmospheres and lower gravity, counterintuitively, flying forms might be rarer, unless the gravity is significantly weaker than on Earth or the atmosphere is only slightly thinner than on our planet. There could also be small planets with very thick atmospheres composed of heavier gases. In such a case, the above doesn’t apply.
  • Walking organisms might be more likely to have bipedal forms and forms with fewer legs. In worlds with very weak gravity, there could even be round and bouncy forms without legs at all. The predator-prey chases would look really strange on such planets.
  • Plant-like organisms could grow to much bigger sizes and provide a habitat to a wide range of other forms of life. There could be multiple tree levels of dense vegetation.

In my opinion, it’s a long shot that small planets in the habitable zone will be found friendly to complex life in other star systems. They are, however, a very good destination for finding simple, unicellular forms in subsurface oceans. We might even find such forms in our solar system in the subsurface oceans of many moons orbiting our gas giants.

The question was: What would life probably look like if there was low gravity?

Content created and supplied by: Jackson46M (via Opera News )

Earth Ganymede Jupiter Tyler Smith

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