In a world I am building, there is a planet named Sentia. Sentia orbits around a G1 star called Prometheus and has two moons, Valkyrie and Cerberus, whose masses add up to around the mass of our moon.

  • Sentia's mass is $8,3608*10^{24}$ kilograms.
  • The radius is about $7.55*10^6$ meters, and the density is $5.515 \frac{grams}{centimeters^3}$.
  • Sentia's gravity is 1 G.
  • Sentia's distance from Prometheus is 1.249831552255972 AU, and the luminosity of Prometheus is 1.25 Solar luminosities.
  • All water on Sentia is contaminated with high amounts of mercury.

All of the numbers were calculated using equations I found online. Is all this realistic to support human life?

  • 2
    $\begingroup$ Just a note: all air and water on Earth have some small amount of mercury (or mercury compounds) in them. As Paracelsus famously said, it is the dose which makes the poison. $\endgroup$
    – AlexP
    Commented May 1, 2017 at 17:58
  • $\begingroup$ Do you mean realistic to support human life? Or are you asking if the numbers are realistic, because they are not far off from Earth's. I assume you based this off earth's density and scaled up? $\endgroup$
    – Firelight
    Commented May 1, 2017 at 17:59
  • 1
    $\begingroup$ Yes, I did base Sentia off of Earth and scaled up, and thank you to whoever formatted this question correctly. I am quite new and have no idea how to format things yet. $\endgroup$ Commented May 1, 2017 at 18:02
  • 4
    $\begingroup$ 1 AU = 149,597,870,700 meters. Your planet's distance to its star has four more significant digits than the definition of an astronomical unit! You might want to scale that back a little, or at least if you're going to such an extreme route, specify whether that's the semi-major or semi-minor axis (and the eccentricity in either case, either by specifying either semi axis and the eccentricity, or both the semi-major and semi-minor axis from which the eccentricity can be derived). $\endgroup$
    – user
    Commented May 1, 2017 at 18:28
  • $\begingroup$ Relevant: What is the habitable zone around my star? $\endgroup$
    – user
    Commented May 1, 2017 at 18:36

1 Answer 1


Seeing as most variables are the same as Earth I'd say that it's safely within the habitable zone of Prometheus. However due to the mercury poisoning it is doubtful that anything bigger than amoeba would evolve there so humans would have to bring their own food supply. The water wouldn't be a problem since mercury filtration is already a thing, and if humans made it to another planet, I'm willing to bet they have that down pat. So all in all, yes, humans could survive there, it wouldn't be fun, and they'd need to bring almost all the resources they'd need, but it's possible.

  • 2
    $\begingroup$ I see no reason why native life cannot evolve a high tolerance for mercury. Consider silver, a highly toxic heavy metal from the POV of a typical bacterium, which (complex) humans can nonetheless tolerate in large quantities. I wouldn't want to eat the wildlife, though. $\endgroup$
    – user25972
    Commented May 1, 2017 at 20:18
  • $\begingroup$ Life here on earth evolved with large amounts of uncontaminated water and when it was introduced to mercury poisoning, it was already complex enough to evolve a resistance. But for complex life to form in conditions where all water has mercury in it is very unlikely. $\endgroup$ Commented May 1, 2017 at 20:39

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