First type - Fluorosilicones in Fluorosilicones, 400° to 500° C

Second type - Fluorocarbons in Molten Sulfur, 113° to 445° C

Third type - Proteins in Water, 0° to 100° C

Fourth type - Proteins in Liquid Ammonia, -77.7° C to -33.4° C

Fifth type - Lipids in Liquid Methane, -183.6° C to -161.6° C

Sixth type - Lipids in Liquid Hydrogen, -253° C to -240° C

The host star of this hypothetical planetary system is 0.80 (M☉), and 0.29 L☉

Now I need help creating the planets to support each biochemistry, I need to know the right mass for each planet, and the distance from the host star each planet needs to be to achieve the right temperature.


1 Answer 1


First and second type: ~0.2 AU

A Mercury-like planet. Mercury's surface temperature ranges from 100 K to 700 K, and a distance to the host star compensated for the different luminosity (just divide by 1.86) is very likely to be Tidally locked. That means that the same side is always facing the Sun, causing different regions to permanently have the Sun in the same position in the sky. The hottest part of the Sun-facing hemisphere should easily reach the temperature required for fluorosilicone life, and closer to the terminator, fluorocarbon life may thrive (alternatively, use a Venus clone for this one). The dark side does actually then have low enough temperatures for 3 and 4 too, but unfortunately no sunlight.

Third type: ~0.5 AU

We know this one works :) The safest option is an Earth clone with scaled distance.

Fourth type: ~0.8 AU

"wet Mars" or "Mars with volatiles". The current surface temperature of Mars fits perfectly for the liquid ammonia case, but the planet should have a little more mass and a stronger magnetic field in order to prevent an atmosphere from escaping.

Fifth type: ~5.1 AU

The obvious comparison here is Titan, but it does not necessary have to orbit a gas giant. At this distance, you are very free to choose the size you want, as there are very easy to hold an atmosphere.

Sixth type:

A tricky one. Liquid hydrogen is really cold. Even Triton, the largest moon of Neptune, is too hot. I can only say that it then must have a orbital distance of >10 AU.

One interesting thing to note is that a tidally locked world could in theory support most of the listed biochemistries (perhaps except for liquid hydrogen, that stuff is ridiculously cold.):


  • 1
    $\begingroup$ +1 Liquid Hydrogen might work on a body like Triton, if one side always faced the local star. The liquid Hydrogen life would evolve on the dark side. Also a robust atmosphere on your tidally locked planet, might ruin the temperature ranges you're looking for :(. $\endgroup$
    – Jim2B
    Commented Mar 7, 2016 at 16:06
  • $\begingroup$ @Jim2B The main part is the single-biochemistry planet distances. The all-in-one scenario is more like a curiosity. It must, as you say, not have a significant atmosphere. $\endgroup$ Commented Mar 7, 2016 at 16:19
  • $\begingroup$ For the first and second type the planet needs to have an atmosphere but not too much like Venus, maybe a larger Mercury could do the job? $\endgroup$
    – Stephanie
    Commented Mar 7, 2016 at 17:21
  • $\begingroup$ @Stephanie I like the idea of a tidally locked mercury, big enough to hold an atmosphere. $\endgroup$ Commented Mar 7, 2016 at 17:29
  • $\begingroup$ With regards to tidal locking: if there's an atmosphere present, the planet's temperatures won't vary enough to support a wide range of different biochemistries. Tidally locked planets with atmospheres tend to generate strong equatorial winds as a result of their thermal differentials, which serve to even out their temperatures, somewhat. These winds also mean that the point directly facing the sun isn't the hottest point on the planet, due to the cooling effect of the wind. $\endgroup$
    – ckersch
    Commented Mar 7, 2016 at 18:37

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .