I have been to Saturn several times last days (*) and I was able to see how bad it would be if the Earth had rings comparable to those of Saturn.

We would have a beautiful firmament, but astronomy would be a very difficult activity, especially during summer, for both hemispheres. The night side of the summer hemisphere of the planet would be bathed by the sunlight reflected on the rings. Scattered by the atmosphere, this bluish glow would make optical observations a difficult task, a job for space borne telescopes, only (the light of the rings would be hundreds of times more intense than the light of full Moon on Earth). The winter hemisphere, though free of the blinding light, would have a great deal of sky blocked for observation, since the rings would obscure the background stars by eclipsing them (although the rings of Saturn are fairly gossamer -the more conspicuous stars are able to shine through them). Definitely, astronomy would be much more difficult.

(*) Thanks to Celestia 3D space simulator; a very cool piece of software (try to approach Saturn system traveling at 6,000 km/sec. Man, it’s very realistic!). And it’s free!

http://www.shatters.net/celestia/

Heh yeah Celestia rocks... (Check my name on the forum there if you haven't already btw! :wink: )

We probably wouldn't have any orbiting satellites if we had rings either- unless they were very thin (as in distance from planet not "thickness")

Anything passing through them a few times would be destroyed wouldn't it? :-?

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That's a great point that I never thought about. You frequently see science fiction artwork of beautiful views, including star lit skies, from the surface of ringed planets. I always thought it would be neat. Bummer about messing up astonomy.

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I haven´t registred yet, though I intend to do it soon. A great forum.

Quick calculations show that if the hypothetical Earth rings had the same proportions as Saturn´s they would begin at 1,500 km altitude and would have a width of roughly 5,000 km. I think it would be possible to orbit Earth within the 1,500 km gap. The ISS would be flying right in the middle of the gap now. Geo-stationary orbits would also be possible, I guess (but I think there would be a greater amount of debris in the vicinity of the Earth – leftovers from the rings - turning the orbital space more dangerous). Things get worse if you consider something like a space elevator. If would be very difficult, if not impossible, to build one.

Yes, I think so.

I durn well hope not! We (Cassini) have to pass through Saturn's rings at orbital insertion, though we aren't going through the thickest part... And it will happen again a few times over the course of the standard mission (and I suspect more during extended mission). Though we are pointing the spacecraft so that no instruments get damaged, just in case.

From what we know, Saturn's rings consist of very small dust. So small that it shouldn't have much of an effect (heck, one of the Voyagers crossed the ring plane without trouble, if I remember correctly). But I agree: it would really bugger up astronomy, if we had one here on Earth.... Probably be pretty though. I'll just have to reserve my condo on Titan, and a good infrared telescope....

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I prepared a pic from celestia, showing how it would look like if you were at the mid latitudes of the northern hemisphere at night (close to midnight) in summer, looking to southeast, on a ringed Earth. Just imagine the glow of the rings, comparing to the full Moon. On my site:

http://planeta.terra.com.br/informatica/ebm/rings/

According to current theories, didn't Earth have rings billions of year ago? Right after that huge object hit and all that debris encircled the Earth, which eventually formed the moon. Obviously it wasn't around for a long time but it WAS there...

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So they say

http://spaceflightnow.com/news/n0209/16earthrings/

In fact, I guess there’s more to the picture, literally.

Case Earth had rings not only the firmament would be different. The planet would likely follow a quite distinct evolutionary path.

The amount of solar radiation received by Earth would be greater by at least the double, due the reflection of the sunlight on the rings. That would have serious implications for the temperature on the planet. Life would likely not have appeared.

Even if life could have emerged and the man could have appeared, our philosophy would be totally different; the “great sickle in the sky” would have given origin to totally different cosmogonies.

There would hardly be any night in the summer, due to the brightness of the rings. Along with a diminished window to the night sky, an astronomical culture – including astrology – would have delayed many centuries [remember Clarke’s “Nightfall”?]

Shame on you, Argos! [-X Asimov's 'Nightfall'!

If Earth had rings, wouldn't the ring system be unstable due to the Moon?

I wouldn't be so pessimistic. The rings would not bar observations completely: consider from near the equator. (Near the poles would be okay for astronomy too.) The brightest planets would still be visible, plus the Moon. Perhaps more importantly, the shadows of the Earth and Moon on the rings might make it more obvious that the Earth is a planet. Rings could even accelerate interest in astrophysics.

O, boy! I deserved a banning for that! I´m sorry! ops:

Saturn´s rings are stable regardless of the complexity of its satellite system. It´s a good question, though I can´t answer it for the time being.

The Moon is much larger with respect to Earth than Saturn's satellites are respective to Saturn. Many say that we might as well call Earth-Moon a double planet...

Wouldn't rings of Saturn's proportions around Earth kill some of the Van Allen belts?

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From the Nine Planets website:

Moon:
orbit: 384,400 km from Earth
diameter: 3476 km
mass: 7.35e22 kg

Dione is the most massive satellite closer to Saturn than the Moon is to Earth:

Dione:
orbit: 377,400 km from Saturn
diameter: 1120 km
mass: 1.05e21 kg

And Saturn is of course larger and more massive than Earth…

There's also another thing to consider. Some astronomers seems to think that Saturn's rings would unstable in the long run, if it weren't for the presence of small, inner "shepherd moons" that keep them in place.

I thought that the "shepherd moons" only sheperded the "F" ring.

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Obviously, these rings present an obstacle to traffic in the Saturn system; any ship inside them would need to clear them in half an orbit, or risk collision, or vice versa.

Despite the fact that they are attractive, I suggest we remove them as soon as possible when we get there; they will provide plenty of water, oxygen and hydrogen if electrolysed; this will supply habitats and provide reaction mass for spacecraft.

There should be a fair bit of Deuterium in that ice too-
what is the chance of He3 in the mix? That would help provide power better than the dim distant Sun...

or should we leave them for aesthetic purposes?

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As bad as the book was, 3001 touched on the subject of ice mining Saturn's rings and the "preservationist movement" that ended it, citing irreparable damage to the ring system. Kinda funny if you think about it, going from treehuggers to icehuggers is not so far a leap...

As for shepard moons, haven't more been discovered in the Cassini gap?[/i]

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The Van Allen belts are concentric, with the maximum activity around 3,000 km, over the equatorial zone, what would coincide exactly with the middle of the ring stripe.

It occurs to me that, indeed, the radiation belts could prevent the rings from forming, or could “disintegrate” them, due to the constant bombing of charged particles. Maybe the Van Allen belts have played a role in dissolving the ancient Earth rings (read about on a link above). Maybe rings and strong magnetic fields are incompatible.

from the link Informant provided:

It was expected that collisions between ring particles would tend to make the rings uniform, but Voyager I found changing structures in the radial direction that are termed "spokes". Some of this structure is shown in the adjacent animation. Here is a smoother and longer movie of the same phenomenon. It is thought that gravitational forces alone cannot account for the spoke structure, and it has been proposed that electrostatic repulsion between ring particles may play a role.

It also occurs to me that the availability of radiation at 1 au from the Sun is many times greater than that at the distance of Saturn.

We could then propose that the environment in the inner stellar system is not favorable to the development of tenuous rings around planets with significant magnetic fields. This means that if we found ringed planets around another star, we should conclude that they a) have weak magnetic fields or b) are located farther than 10 au from the star.

According to this proposition, if we found rings on planets close to the stars we should conclude that a) the planet (and/or the ring) is recently formed, or b) the planet´s magnetic field is not significant.

The proposition does not explain why planets have rings, but outlines the condition for a planet keeping them.

This proposition is consistent with the solar system evidence: Jupiter, with a strong mag field, and yet significant incoming radiation, have tiny rings, which might have been huge in the past, whereas Saturn can maintain a ring system, because of both the weak magnetic field and the poor amount of radiation that reaches it. The failed rings of Uranus and Neptune would have to be explained by other processes, since radiation would not contribute to their disintegration (case they have been more prominent in the past), regardless of the planets having or not a magnetic field. This proposition is also consistent with the findings of extra-solar giant Jupiters so far: they are located next to the star and none of them has proved having rings (discounting the fact that they can´t be directly seen).

Well, I think this thread, which started as an innocent gedanken experiment, has given, thanks to Kucharek, a great contribution to human knowledge. I think we got a whole new theory here. :wink:

Edited to fix an error

The spokes rotate with Saturn's rotational period and also would defy Kepler's law if they had something to do with gravity. AFAIK, it's some interaction between the magnetic field of Saturn and charged particles in the rings when they leave Saturn's shadow.

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