Life on a ringed planet

[Lomitus]

Hey Folks,
I don't post here very often any more, but I was just looking at some of the new pics of Saturn taken by Cassini and an interesting thought crossed my mind...

Ok. I will admit this really kind of borders on science fiction but as I was looking at those pics, I realized that the rings from Saturn cast a pretty serious shadow on the planet itself. Now please, I'm not reffering to Saturn it's self here so -please- don't be too literal. My question is, if people lived on a ringed planet, how would the shadow from the rings effect your "day light"? I mean, would it look cloudy and over cast even if there were no clouds in the sky or would that area just appear in darkness as in the middle of the night? I'm sure it would depend on the density of the rings themselves and all, but I would think it would be kind of interesting


Just entertaining some thoughts of the unknown...
Bright Blessings,
Jim

[antoniseb]

If the ring plane was not right on the ecliptic, the ring shadow would certainly cause some serious weather. As to how dark it would be behind them, theat depends on the rings. Some of Saturn's rings are pretty close to opaque.

Early civilizations would much more quickly figure out that their world was round and might more easily be able to solve the puzzle of determining longitude.

[TheThorn]

OK, Anton, I gotta bite. How would a ring help with the longitude problem?

[blueshift]

It appears that we may have had rings as glorious as Saturn's in our own past.
Go here.

blueshift

[QJones]

Actually, it might make it easier to learn that the world was round.

In additon, having near-space resources might be a boon for a space-exploring society. I think we could really benefit if earth had massive resources in orbit, in that the cost of boosting resources would be lower. (some would say, quit whining, the Near Earth Asteroids are enough, but still every benefit would help).

I agree though, that weather would be quite different. With an earthlike revolution (where the angle of the ring-shadow changes with the season) you'd have winters at the poles and winters (maybe) in the shadows. That would be quite neat.

[antoniseb]

Originally posted by TheThorn@Feb 16 2005, 01:29 AM
How would a ring help with the longitude problem?

The rings would be close enough that diurnal parallax could tell us the precise distance to them with fairly primative measuring tools, especially related to where the Earth's Shadow makes a fairly distinct line across them. The parallaticum gives good measuements to about 3 minutes of arc.

The next thing that needs to be there for the determination is a good prediction of the position of the moon as twice a month it goes passed one of the shadow lines. [events in pairs about a day apart]

Given the observed elevation and the latitude above the horizon of the moon as it passes this line, it would be possible to calculate the longitude of the observing location. The math is ugly, but was known by the Greeks, and was certainly recovered by the muslim scientists, and known well in Europe by the fourteenth century, and probably earlier.

Another way it could be done is simply observing when the moon occults the disk of the rings from a given location, and the elevation of the moon at the time. This happens four times a month.

[Erimus]

I don't think the rings could realistically be opaque unless the ring were *very* massive. However, if we're talking about an Earth-like planet with rings of the same extent, density and relative mass to the planet as Saturn's, with a similar axial tilt to Earth, then we would probably see some serious climatic effects.

Temperatures in the winter hemisphere (which would always be in the rings' shadow) would be quite severe, if only a few percent of the already weak sunshine got through. Temperatures in the summer hemisphere would probably be normal, though. So we'd have a pattern of very cold winters and hot summers; that kind of hemispheric inequality might create some very interesting and vigorous weather patterns.

[Essel]

In addition..

A ring like Saturn could mean a feature appearing like 3000 mile high mountain at the equator of earth, this would surely be dominatingly visible from almost half the globe. If such a ring is made up of ice, the reflections and other optical phenomenon will be spectacular and shall add to the variations in climate. If the ring is not opaque, there could be twilight throughout the night!

[Nereid]

Extending the question - what would the rings look like from the surface of the planet?

Assume three rings - similar to Saturn's A, B, and C ... at comparable distances; assume a 23.5 degree axial tilt (like the Earth) and don't forget that the ring plane coincides with the equator.

If you lived at the poles, would you see the rings at all? No matter where you lived, would the be a 'ring-rise' and 'ring-set'?

[gavwvin]

Imagine if Earth had rings around the equator- we would see them in the sky where the imaginary celestial equator is, that is intersecting the horizon at exactly East and West and arcing up to their highest point at South (or North if you were in the Southern hemisphere).
At the poles it would be just out of view on the horizon... At the equator it would be directly overhead... in general their elevation (at the highest point) would be equal to 90 degrees - your latitude.
As the rings run in the same direction as the planets spin, they would not rise and set, the same as the celestial equator here never rises or sets.

[Nereid]

Excellent!

On an airless (spherical) planet, if you stand at a pole, you cannot see the top of even the tallest mountain on the equator; would the outer edge of a ring system be within the Roche limit for you to be able to see it from a pole?

If the Earth had rings like Saturn, could you see them if you were at the Equator?

At mid-latitudes (say, 30 to 50 degrees), how bright would the rings be when lit (you view the sunlit side)? when not (you view the side from 'behind&#39?

The Moon is clearly visible in 'earthshine' while it's still young; would rings be visible by 'earthshine'?

If you were in 'ring-shadow', how much darker would it be at noon than if there were no rings?

[gavwvin]

I suppose we would get frequent "eclipses" at mid-latitudes where the rings would pass in front of the sun, however I would think it wouldn't be like a solar eclipse as it is not one coherent structure like the moon where no light could get through- it would depend on the density and opacity of the rings.
At the equator I suppose it would depend on the thickness of the rings whether we could see them or not, if their thickness was negligible compared to their distance, they wouldn't be very clear, just a thin line directly overhead.
Very interesting question!

[Dave Mitsky]

Originally posted by antoniseb+Feb 16 2005, 05:00 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (antoniseb @ Feb 16 2005, 05:00 PM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-TheThorn@Feb 16 2005, 01:29 AM
How would a ring help with the longitude problem?

Edit

Another way it could be done is simply observing when the moon occults the disk of the rings from a given location, and the elevation of the moon at the time. This happens four times a month. [/b][/quote]
For this to happen the moon would have to be closer to the planet than the rings are. Is that what you meant to say?

Dave Mitsky

[rabeldin]

You might also enjoy Larry Niven&#39;s Ringworld, a classic scifi novel.

[Darrrius]

If you want to imagine what it looks like on extrasolar planets the follwing link will provide inspiration. Some of the stuff here is purely fanciful, but some is based on artistic impressions of data


http://www.dotphoto.com/GuestViewAlbum.asp?AID=207098