In our solar system, Europa, a moon of Jupiter, has a large and warm ocean under the icy crust. However, due to it having a rocky core and the icy crust, there is no light in the ocean. I want to make writing life, society, and technology easier by making natural light sources on Europa exist long before life evolved.

In this way, life on Europa can have functional eyes and form a society like Jar Jar Binks's in Star Wars. What kind of geological change needs to happen to make a "illuminated ocean" in Europa possible?

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    $\begingroup$ "In our world, Europa, a moon of Jupiter" - Well, Europa is not in our world. Earth is our world. $\endgroup$ Commented Nov 23, 2022 at 18:25
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    $\begingroup$ It is my very sincere advice that all authors strive to do far better than "Jar Jar Binks [from] Star Wars." No matter what you are working on, it can and should be better. $\endgroup$
    – Tom
    Commented Nov 23, 2022 at 19:35
  • $\begingroup$ @Tom somehow I surmise the latter trilogy of movies has been written by Jar Jar... $\endgroup$ Commented Nov 23, 2022 at 20:38

4 Answers 4



Organic things can generate light! Some creatures on Earth do this:

Glowworm stuff in a cavern with photoshopped tourists in a small boat acting stupefied

(No, not the guy in the front of the boat! The stuff on the ceiling!)

All the Earth examples I'm aware of are in creatures, but there's no reason this couldn't be done by lichen or some other comparatively simple lifeform. Why might that happen?

In a vast and dark ocean, emitting light makes you the center of attention. Nearby organisms will use your light as the fixed point around which they orient their activities. Some will gravitate towards your light, others will carefully hang out near the very edge of your light, still others will deliberately lurk in the darkness just outside so they can prey on the nearer lurkers. Near or far, they're all dancing to your tune. It is a primordial form of "working the refs": by emitting light, you establish the environment in which all the other players play, which makes it a lot easier for you to eke out a win in any scenario.

Concretely: making yourself the hub of activity increases the likelihood that other lifeforms will collect and drop resources (including their own corpses) near you. It becomes more likely that the various "gathering" activities of other life will result in depositing those gathered resources near you. Maybe you can use those resources. Maybe those resources attract other life, driving the cycle.

The winners are invariably the ones who warp the playing field to their own advantage. Like Jesse Ventura said: "win if you can, lose if you must, but always cheat."

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    $\begingroup$ I was musing about bioluminescence evolving out of the ability to perceive infrared - heat. Infrared is electromagnetic radiaton. Finding heat might be good for beasts in the cold sea - nutrient sources, or prey. Once you can see one wavelength maybe you can see others? $\endgroup$
    – Willk
    Commented Nov 23, 2022 at 19:54
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    $\begingroup$ +1 Came here to write this exact answer. The ability to sense heat/light puts you at a clear advantage above those that can't. It wouldn't be surprising if Europan life (supposing it existed) bioluminesced. $\endgroup$
    – BMF
    Commented Nov 26, 2022 at 15:58

There are a number of naturally occurring minerals that phosphoresce -- zinc sulfide, for instance, can store energy from exposure to light and will then continue to glow for some time, but can also be directly excited by UV radiation and immediately gain brightness.

So, what's needed is to have a relative abundance of phosphorescent minerals (look up what was used as phosphors in fluorescent lamps or old CRT television screens) and a source of excitation for them. The excitation might be an alpha- or beta-emitting radioactive element mixed in with the phosphors, for instance (both alpha and beta area pretty readily shielded by water, especially salt water).






The ice crust of Europa has cracks. Big old ones, small new ones. These cracks are brown presumably from accumulated tholins: carbon and nitrogen rich molecules.

From underneath, a crack will be brighter than adjacent ice. It will also be a place where there will be a bloom of life because of the carbon and nitrogen rich stuff coming thru. Things that can see the light can find the resources.

And then: Jar Jar!


I think it really depends on what kind of an atmosphere you want to create for your world As previous comments have suggested, you could use bioluminescence to have life. If you want to, you could use the fact that all materials emit light assuming they are above 0 Kelvin. This would create infrared light rather than visible though. You could also use some kind of radiation source or maybe even the core of the earth. Or maybe the civilisation came from another planet where there was more life


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