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lpetrich
2010-Jan-24, 05:15 AM
What Earth Would Look Like With Rings Like Saturn (http://www.youtube.com/watch?v=hoz5Q2rGQtQ&feature=player_embedded) (YouTube video)

I myself have crunched the numbers on its appearance and behavior, and for a reasonable size (1.5 to 2.5 Earth radii), I find:

If they behave like Saturn's rings, then their shadowed side will be darker than their sunlit side by about a factor of 2 or so.

The rings will be brightest at the solstices, and dimmest at the equinoxes.

At midlatitudes away from the equinoxes, the rings would be so bright that they would make the sky a perpetual twilight. Their luminosity: about a few thousand lux (the full Moon: 1 lux). One would be able to read by their light. But a day from the equinoxes, their brightness would go down to about 50 lux, which is still brighter than the full Moon.

The rings will be warped about 6m of arc by the competing gravity of the Earth's equatorial bulge, the Moon, and the Sun. At the equator, one will be able to observe that width, and it will make the rings' maximum brightness about 20 lux, declining to 0.3 lux near the equinoxes.

The rings will not be visible from latitudes greater than about 60d.

Visibility of some celestial objects:

Venus at its brightest will always be visible
Mercury, Mars and Jupiter at their brightest will not be visible from midlatitudes at the solstices, but will be visible at other times and places
Sirius will be visible at the equator and a few days from the equinoxes at midlatitudes
Saturn, Vega, and Alpha Centauri will be visible at the equator, but only very briefly at midlatitudes - at best


So it would be VERY hard to do astronomy without going to far northern or southern latitudes. However, on the plus side, astrology would likely be much less well developed.

But it will be almost absurdly easy to discover from the Earth's shadow on the rings that the Earth is approximately spherical. One will also see the Moon's shadow on the rings when the Moon is making a solar eclipse.

novaderrik
2010-Jan-24, 07:04 AM
if the earth had rings, then i'd think that the moon would do a pretty effective job of destroying them, thus the earth wouldn't have rings.
actually- i take that back. the earth is kind of developing a "ring" system due to all the stuff that we are lobbing up into equatorial orbits.

EDG
2010-Jan-24, 07:55 AM
Earth's rings would be a lot more temporary than Saturn's because of tidal effects from the sun and moon. Also, they wouldn't be anywhere near as bright because Saturn's rings are made from ices that wouldn't survive at earth's distance from the sun - we'd have rings more like Jupiter's or Uranus' - dark and dusty, because they'd be made of silicate material.

lpetrich
2010-Jan-24, 10:12 PM
How would those tides be seriously disruptive? Can you work out some numbers or point me to some papers in the professional literature?

The ring particles will end up in orbits that are very close to circular and coplanar, so perturbations by the Moon and the Sun will have about the same effects on neighbors. The Moon and the Sun differ from possible nearby satellites in having *much* smaller angular velocities, meaning that particles can adjust much more easily.


Turning to the rings' brightness, they would likely have an albedo close to that of the Moon, about 5% or so. However, they are nearly 100 times closer to the Sun than Saturn's rings, which more than compensates for their lower albedo.

APODman
2010-Jan-30, 03:30 PM
Sandia researchers have proposed that the Earth may once have possessed a ring caused by ejected material of impacts of meteors and comets in the past. The presence of this ring could still have been responsible for climate changes.

But simulations show that a ring around our planet would not be stable over 5 years depending on the initial orbital elements.

The life of the ring would be 80% smaller if taking account the oblateness of our planet in simulations !

If a ring system existed it should be continuously maintained with new material for extend your existence.

More in:

- "IMPACT-INDUCED CLIMATE CHANGE DUE TO AN ORBITING DEBRIS RING" (http://est.sandia.gov/earth/docs/Impact-Induced_Climate_Change.pdf)

- "Rings around the Earth: A clue to climate change?" (http://www.sandia.gov/news-center/news-releases/2002/earth-sci-fossil-fuel/ringworld.html)

- "Preliminary Analysis of a Hypothetical Ring System in the Inner Planets: Earth and Mars Cases" (http://www.astro.iag.usp.br/~corot/natal/silvia.ppt)


[ ]īs

Romanus
2010-Jan-30, 06:34 PM
This a nifty, informative little thread. :)

What would be fascinating (but very difficult) to model is the effect rings would have on climate. Presumably the shadow of the rings would significantly cool the winter hemisphere by decreasing the overall insolation; no doubt the equator would much cooler on average as well, even though it would be directly in shadow only near the equinoxes.

What would really be amazing would be seeing the Moon's shadow cut across the rings during an eclipse, an effect which would presumably be visible well outside of the path of the eclipse itself.

lpetrich
2010-Feb-09, 08:38 AM
The tropics wouldn't be shadowed very much by the rings -- it's the midlatitudes that would be shadowed the most by them, and shadowed in the winter.

In fact, near the equator, they'd look very thin. I suggest watching the video I'd linked to in my first post - it will show what the rings will look like.


What would happen if the Earth got such rings right now?

It would quickly go into a very bad ice age, but that would gradually end as CO2 accumulated in its atmosphere. During the late-Proterozoic Snowball-Earth period, there were some especially big ice ages that would last some 20 million years each (Wikipedia: Cryogenian), so that's a likely upper limit on how long it will take.

But once it is present, it will keep the Earth at a new equilibrium. It will make midlatitude summers hotter and winters colder, meaning the end of the recent series of ice ages -- the Greenland and Antarctica glaciers will likely melt.

I'd have to have some climate-modeling software on hand to test these predictions, however.

wd40
2011-Jul-27, 09:14 PM
Would satellites, shuttles and space stations be able to survive in the space surrounding a ringed Earth? Would any form of manned mission and its reentry even be possible?

Rhaedas
2011-Jul-27, 09:29 PM
It would be more of a challenge. Depends on how dispersed and the area covered, as well as if the object is moving in the same direction as the ring's orbit. If so, then the debris velocity would be minimal, so it probably wouldn't be as dangerous as our current debris in orbit.

It would also likely play havoc with using geosynchronous orbit for relaying information, again depending on how spread out the material actually is.

ZunarJ5
2011-Jul-28, 04:54 PM
Would the shadow cast by the rings be more significant on a hemisphere with the seasons? Wouldn't the southern hemisphere get more shadow when the north was in summer and vice versa? Or am I picturing it wrong?

Romanus
2011-Jul-30, 04:00 PM
^
That's about right; the winter hemisphere would get most of the the shadow, and the equator only at and around the equinoxes. I still contend that the shadow would have unpredictable seasonal effects, given the fact that we know the atmosphere is extremely sensitive to small changes in insolation, even though--as the earlier thread mentions--the actual obscuration would not be great.

As for getting into orbit, I think it would be extremely difficult. Yes, if we did so in the equatorial plane the relative velocity of the particles would be low, but there would still be a lot of them; at the very least we'd probably be looking at heavy particle shields for the simplest spacecraft. For going beyond LEO, you'd need either a huge amount of delta-v to get past the rings altogether, or heavier shielding as you plowed through the ring plane at least once, and more likely twice on the way out. Honestly, extremely low polar orbits would probably be the best bet; the relative velocity of the ring particles would be much higher, but the exposure would be shorter; also, if they're like Saturn's rings, they'll be very thin close to the atmosphere.

Martijn
2011-Aug-05, 11:59 PM
The rings look very close to earth in the video, shouldn't they be further away from the earth?

Gsquare
2011-Aug-06, 12:52 AM
What Earth Would Look Like With Rings Like Saturn (http://www.youtube.com/watch?v=hoz5Q2rGQtQ&feature=player_embedded) (YouTube video)

.

Believe it or not....The earth already had rings at one time....
see my BA thread here:
http://www.bautforum.com/showthread.php/119289-Are-you-aware-that-earth-once-had-a-Saturniam-like-ring-around-it
:))