I am developing a terrestrial, habitable planet with rings about the width of Uranus' rings. Not extremely thick, but still noticeable.

I have heard that rings on planets would cause an inhabitable zone around the equator because the sun does not reach past the shadows of the rings.(correction : this is not true, thank you for informing me) I wanted this to happen and instead of struggling with ways to make that zone habitable, I thought of creating an all-around-the-equator "elevator" that transports goods and resources from the planet to the rings and vice versa — and perhaps beyond (to the planet's moons, for example).

I understand transporting through the rings to e.g. a moon would require a stable gap in the rings to pass through, which is also something I want to know if it's possible.

The reason the elevator is all around the equator is for the case of the planet's moons. Instead of having to wait an entire lunar cycle for a transport window and then only be allowed a short time for transport, why not make the elevator follow the natural satellite's orbit? (Which is another thing I'm not sure is possible.) Additionally, I've considered elevator stations on each moon so transports from one to another are possible, even if this factor is time-limited just to widen potential mining facilities, and perhaps a prison? who knows.

While all of this is entirely science fiction, I still want to implement hard-science-proven elements.

edit : I really appreciate the help, the information I've been provided will help me tremendously with my story. And thank you for the grammar edits, I'll do my best to improve that myself in the future and I understand you took your own time to do it, which was really sweet :) I'll also keep in mind the fact I should keep my questions short, which means you will see a lot more of me around so enjoy that

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    $\begingroup$ "The sun does not reach past the shadows of the rings": (1) It is not true. The rings are not completely opaque; and those of Uranus specifically are quite transparent. (2) Even if they were completely opaque, so what? The planet rotates. At any given place there will be a short time of night in the middle of the day. Big deal. There is always a very much longer night every day, and that's perfectly fine. $\endgroup$
    – AlexP
    Commented Sep 28, 2022 at 22:34
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    $\begingroup$ Could you please use proper capitalization, and maybe break up your text in paragraphs? That will make it much easier and more welcoming to read :) $\endgroup$
    – Joachim
    Commented Sep 29, 2022 at 2:50
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    $\begingroup$ Welcome to Worldbuilding. I took the liberty to edit your post to clarify it and make it easier to read. For the record, writing a wall-of-text (no paragraphs) all in lower-case is a bad habit to get into. Note that I felt your question was reasonably clear with two exceptions, your Q would be improved with a link to the source of rings leading to an inhabitable zone and you need to explain what you mean by "temporary deposits." I also removed the science-fiction tag. If you read the mouse rollovers, you'll see science-based and science-fiction can't be used together. $\endgroup$
    – JBH
    Commented Sep 29, 2022 at 3:48
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    $\begingroup$ @JBH Reminds me of this XKCD What If: Earth-Moon Fire Pole $\endgroup$
    – KC Wong
    Commented Sep 29, 2022 at 4:31
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    $\begingroup$ @KCWong That's actually a pretty good XKCD to have here! It's easy to find the Earth's rotational speed (~1,000 mph) and we're tempted to just subtract the two (Mach 2! Whoopee!) except that the moon is a long way away, which is why the XKCD can claim the Earth is rotating faster than the moon (elevator moving against the prevailing westerlies... ouch!). But it also leads us to ask what happens when the moon is moving toward the sun (speeding up) or away from it (slowing down)? That gravity issue is whomping nasty, too. The idea is cool, but it would need to address a lot of issues. $\endgroup$
    – JBH
    Commented Sep 29, 2022 at 4:54

1 Answer 1


Rings and moons don't work quite as you imagine. However, the idea can be adjusted to fit reality.

Rings Are Less Dense Than A Cloud

i have heard that rings on planets would cause an inhabitable zone around the equator because the sun does not reach past the shadows of the rings

AlexP points out two problems the comments. First, the rings of Uranus are very thin (perhaps 150m), quite diffuse and made of rocky material. The result is a very low optical depth which means most of the light gets through. Even the rings of Saturn are at most 140g/cm^3, ten times less dense than air on Earth. The rings are not solid; they are made up of many small bodies, dust, and particles. The resulting shadow, if any, would be quite diffuse.

Think about a cloud on Earth; it casts a shadow, but it certainly doesn't make the surface uninhabitable. Now think about it ten times less dense and also 40,000 km away. You wouldn't even notice.

If the planet has any axial tilt its rotation will mean the shadow falls on a different part of the planet at different parts of the day and year.

The Apparent Size of the Rings is Far Too Small

Imagine trying to shade yourself from the Sun with a hair.

We get lunar eclipses on the Earth because the Sun and the Moon appear to be about the same size in the sky. If the Moon were any smaller, or more distant, we wouldn't have full lunar eclipses.

Even with zero axial tilt, there would still be no shadow. The Sun is not a point source of light, it is 1,400,000 km wide. The rings are just 150 m thick. Light from the top and bottom of the Sun would peek over the top and bottom of the very thin rings.

We can do the math to confirm. Angular diameter is $2 \arctan{\frac{d}{2D}}$ where $D$ is how far away it is and $d$ is how wide it is.

To create a shadow, the thickness of the rings would have to appear as wide as the Sun appears; the apparent size of the rings needs to be larger than the apparent size of the Sun. Using Uranus as an example, it's closest ring oribts at 40,000 km. Let's bump up the thickness to an even 1 km. That makes the apparent size from the surface 25 microradians. In the Earth's sky the Sun is 9200 microradians. The ring would cast no shadow, just a very, very, very faint penumbra.

You can fiddle with the numbers to make it work. At the very low orbit of 4,000 km (probably too low to have a stable ring system) and a thickness of 10 km, a ring system could blot out the Sun if the Sun were 4 times further away than from Earth.

To sum up, planetary rings are...

  1. Far too thin to block the Sun.
  2. Optically shallow.
  3. Not solid.
  4. Typically tilted with respect to the Sun.

This means any shadow will be almost unnoticeable and will move with the time of day and year.

Space Elevator

i thought of creating an all-around "elevator" of sorts that transports whatever needs to be moved from the planets to rings, vice versa and perhaps beyond (to the planet's moons, for example)

Since the rings are not solid transporting "to" the rings doesn't make sense. However, material transporting into orbit makes sense! This is a space elevator. Once built it makes traveling into orbit very cheap. Every good civilization needs one if they're really serious about getting a large amount of people and stuff into space.

A space elevator can be made if A) gravity is low enough and B) your materials are strong enough. We can't make one on Earth because our gravity is too high and our materials are too weak, but we could make one on the Moon. Your planet could have low gravity and/or very strong sci-fi materials.

the reason the elevator is all around the equator is in the case this planet has moons, instead of having to wait an entire cycle and only be allowed a shortened time of transport, why not make the elevator follow the natural satellite's orbit?

A space elevator needs a counterweight at the end of the tether. This counterweight needs to remain above the anchor of the space elevator on the planet's surface. Normally you'd put an object into geostationary orbit, but to counteract the tension from holding the tether up requires it be put far beyond geostationary orbit.

Rather than launching it from the surface of your planet, a small moon in about the right orbit would do nicely. Phobos has been proposed for a theoretical Martian space elevator.

  • $\begingroup$ Deimos is the Martian Moon that's nearly in the areosynchronous orbit. Phobos is much closer in. Admittedly, if you're going to build a Martian space Elevator, you'll have have to construct to avoid Phobos, operate to let the cable dodge it, or move it. $\endgroup$
    – notovny
    Commented Sep 29, 2022 at 20:04

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