9
$\begingroup$

Is it possible for a planet (with an atmosphere and breathable air obviously) to be super far away from its star but still have a habitable surface temperature just from geothermal activity alone, if so, would there be any bad side effects?

$\endgroup$
9
  • 1
    $\begingroup$ How was the oxygen in the air created and sustained without light and photosynthesis? $\endgroup$
    – Uwe
    Apr 20, 2022 at 6:37
  • $\begingroup$ Cuz it still orbits a star? I literally stated that it did orbit one it's just far away $\endgroup$ Apr 20, 2022 at 7:06
  • 1
    $\begingroup$ If the planet is " super far away from its star" the light on the planet is much too weak for photosynthesis. $\endgroup$
    – Uwe
    Apr 20, 2022 at 9:29
  • $\begingroup$ Well it's not really important to the question anyway $\endgroup$ Apr 20, 2022 at 11:06
  • 1
    $\begingroup$ Photosynthesis could be replaced with harvesting thermal energy of the planet. Pretty much everything could be based on that. One serious problem though, to achieve such surface temperature you'd need very shallow magma, very thin planetary crust, very high internal temperature, and that inevitably means convection currents and extreme seismic activity. Poisonous vapors from countless volcanoes, endless eruptions and earthquakes, conditions so unstable and hostile no life could thrive in one place for long. $\endgroup$
    – SF.
    Apr 20, 2022 at 13:00

4 Answers 4

7
$\begingroup$

Yes, it is possible that geothermal activity can achieve habitability. In 2018, a group of scientist discovered an extrasolar planet (Barnard’s Star b) orbiting Barnard’s star, an M-type (red dwarf) that is 6 light years away. It is at least 3.2 times as massive as Earth and experience average surface temperatures of about -170 °C (-274 °F) making it both a "Super-Earth" and "ice planet". Based on this, many have concluded that the the planet would be hostile to life but according to new studyref. by a team of researchers from Villanova University and the Institute of Space Studies of Catalonia (IEEC), it was predicted that the planet has a hot iron/nickel core and experiences enhanced geothermal activity and it can thus support life.

The planet orbits Barnard’s Star at a distance of about 0.4 AU, so it only receives about 2% of the energy from its star, so others hypothesized that life was not possible. However, the recent study shows there are still possible scenarios in which subterranean life could exist. These include the possibility that while the surface may be icy cold, geological activity might allow for life beneath the surface. They quote:

Geothermal heating could support "life zones" under its surface, akin to subsurface lakes found in Antarctica. We note that the surface temperature on Jupiter’s icy moon Europa is similar to Barnard b but, because of tidal heating, Europa probably has liquid oceans under its icy surface.

Ref.: https://www1.villanova.edu/villanova/media/pressreleases/2019/0110.html

$\endgroup$
9
$\begingroup$

I'm going to make the assumption that you mean life other than humans. Humans can survive anywhere with enough technology, even frozen, lifeless rocks. We don't even need a planet, as our experience with long-term space habitation has shown we need gravity, and at some point in the relatively near future we will be able to build habitats which will spin to simulate gravity. On your proposed planet thermal energy would be useful as it would be a way to generate electricity and heat habitats, but we could use nuclear reactors or other technology to produce electricity if that wasn't available.

All you need for life is some building blocks and most important, a form of energy. Light is only one source of energy, on our planet most life is reliant on the sun in some way, but even on our planet we have found life that have evolved to live off heat. The best example I can think of is microbes that live near deep hydrothermal vents, and the animals that feed off them. There's a whole ecosystem near underwater volcanic vents which is completely independent of light. So it is possible that life could evolve on a planet that still has a molten core and volcanic activity.

$\endgroup$
9
  • 1
    $\begingroup$ According to some theories, these hydrothermal vents is where some early stage of evolution of live happened on earth. That being said, the planet needs some sort of insulating layer (maybe an ice crust on top of the oceans) to prevent cooling beyond the heat that the core could provide $\endgroup$
    – Hobbamok
    Apr 20, 2022 at 10:17
  • 1
    $\begingroup$ It's certainly possible @Hobbamok. You wouldn't have to have an ice layer, there could be interior areas where life could exist in some form, but it would certainly help. $\endgroup$
    – GdD
    Apr 20, 2022 at 10:19
  • $\begingroup$ The ISS does not show us anything. The amount of time humans have survived on it without resupply is trivial. "some gravity is good for us" is too vague to draw any conclusions, when the longest stay in space is less than a year and a half, and that required hours of exercise every day, and took months to recover. The only concrete thing we know is that humans can just about survive a year and a half in space, if resupplied, kept on a strict exercise regime, and given months to recover lost bone density. Bit of a stretch to assume we can do it indefinitely. $\endgroup$
    – Innovine
    Apr 20, 2022 at 11:53
  • 1
    $\begingroup$ @Innovine, My point is that technology solves those problems. Our experience with long-term space habitation has given us an understanding of what it would take to live in space long term. We can spin a future station to simulate gravity and prevent bone loss, and provide radiation shielding. However, that's not what the question is about. $\endgroup$
    – GdD
    Apr 20, 2022 at 12:10
  • 2
    $\begingroup$ Rather than "life other than humans", I think the OP means "naturally-occurring life". $\endgroup$
    – Barmar
    Apr 20, 2022 at 14:24
0
$\begingroup$

Arguably we already know of a planet where internal energy from the planet sustains life. According to the National Oceanic and Atmospheric Administration:

Organisms that live around hydrothermal vents don't rely on sunlight and photosynthesis. Instead, bacteria and archaea use a process called chemosynthesis to convert minerals and other chemicals in the water into energy. This bacterium is the base of the vent community food web, and supports hundreds of species of animals.

In the case of Earth, geothermal energy is known to work hand in hand with geochemical energy. The heated water facilitates reactions that produce the reactive chemicals, such as hydrogen, hydrogen sulfide, or even dissolved ferrous iron from mafic rock that serve as fuel sources for biological processes. Such biological processes are widely seen as a model for possible life in subterranean oceans in ouer Solar-System moons, where the oceans are supported by geological processes that (given the necessary minerals) may also generate chemical reactions similar to those evident on Earth.

$\endgroup$
0
$\begingroup$

Geothermal energy can be extracted from the temperature difference (on the surface vs in depth) but this needs a large organism more like a large underground tree with specific structure. A small cell would have the same temperature over it and could not use the gradients.

But some microorganisms, if required for the beginning of evolution, could evolve using chemiosynthesis first.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.