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lpetrich
01-28-2010, 07:02 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.

Sophia
01-28-2010, 03:15 PM
That was lovely, thank you for sharing it. What prompted you to make this video?

kaitie
01-28-2010, 03:49 PM
That was amazing! Thank you. :)

jvc
01-28-2010, 04:51 PM
I found that very interesting, thanks. :)

efkelley
01-29-2010, 05:09 AM
Pretty neat. They could also serve as a navigational aid.

lpetrich
01-29-2010, 07:05 AM
That was lovely, thank you for sharing it. What prompted you to make this video?
I'm not the one who made it. I'm just someone who found it interesting.

But the calculations are mine.

Alex Bravo
01-29-2010, 07:19 AM
What would the ancients have thought? Or what Myths would explain it?

lpetrich
02-02-2010, 11:17 PM
They would have invented some Just So Stories to explain their existence -- something like the oodles of Just So Stories that people of our world have invented.

Why not research some origin myths some time? Many of them have various things in common, like Lamarckian inheritance, so you might be able to think up some plausible origin myth for those rings.

blacbird
02-05-2010, 06:27 AM
If we keep proliferating space junk at the accelerating rate we are, we just might develop Saturn-like rings.

caw

thothguard51
02-05-2010, 09:06 AM
The rings would also throw shadows on the earth during certain times of the years due to distance from the sun as well as tilt degree. This in turn would change climates. The ice ages may have lasted longer...

Xelebes
02-08-2010, 03:15 AM
The rings would also throw shadows on the earth during certain times of the years due to distance from the sun as well as tilt degree. This in turn would change climates. The ice ages may have lasted longer...

Possibly, but it would probably make the tropics have four seasons, depending on how dense the rings were. The space between the tropics and the temperate zones would have the closest semblance of a tropical climate. That being said, the reflection of the rings would cause light not to hit the tropics and thus, I think, we'd lose the trade winds and the equatorial currents as we know them.

lpetrich
02-08-2010, 11:44 PM
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 (http://en.wikipedia.org/wiki/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.

jinkang
02-09-2010, 07:53 PM
How about agriculture? Wouldn't that affect the type of food that will grow in certain regions?

small axe
02-10-2010, 02:52 AM
I think Nat.Geo. Channel on TV is having a three part "tour guide to the planets" coming up this Sunday (I think it's Sunday anyway)

I only mention it here because the promo commercial talks about the rings of Saturn ... and I probably misheard but I thought they said the rings are only a few hundred meters thick?

I imagined the rings as vast, and full of debris ranging from dust-sized to debris the size of ... I dunno ... elephants. (So I may have mis-heard. But the first show is about RINGS anyway ... and freezing rains of liquid nitrogen or something? It sounded extreme)

Pthom
02-10-2010, 03:11 AM
I think your idea of particle size is correct, small axe. but the rings are indeed very thin, measured in a north-south direction. In a hundred meters, you could stack up several elephants. :D

small axe
02-15-2010, 02:09 PM
Yeah, the show was on, Saturn's rings are like ... crazy! Crazy beautiful and crazy odd.

Lemme ask: when we "see" photos of outer planets like Saturn, even when they're photos from our space probes ... those are colour enhanced, right?

I mean ... if you were on the probe, looking out the window at Saturn? Is there enough SUNLIGHT hitting Saturn from a billion miles away, that we could see it out the window with our naked eye?

Or are all the space images, Saturn and the Hubble images, basically artificially enhanced?

Even as I write it, I realize -- we can point a telescope at planets and see them, so there must be visible light bouncing back.

But colours fade (to our eyes) even at night, here on Earth ... ?

So ... well, that's just amazing then. Light leaves the Sun, goes a billion miles to Saturn, bounces back another billion miles and into our eyes? In all the pretty colours!

Weird Universe.

It was a cool show, GUIDE TO THE PLANETS on NatGeo Channel. They played the "sound" of the probe getting sprayed by ring debris as it dipped thru the rings. Fortunately, none of the elephant-sized pieces smacked it!

In another show, about Jupiter, it said if you stood on one of its moons, the radiation coming up off Jupiter would fry you in five minutes!

Pthom
02-16-2010, 01:14 AM
In another show, about Jupiter, it said if you stood on one of its moons, the radiation coming up off Jupiter would fry you in five minutes!Then you'd better have on some SP4x10^6 radiation protection. :D

And you wound up answering your own question about the appearance of images Saturn and other planets. Yes, the images from space probes are enhanced. They are created almost exactly like your digital camera takes pictures, but "read" only light and dark (hence, the "raw" image is black and white, or shades of gray). However, they take several pictures through various filters. The ones that relate to pictures you see of Saturn, Jupiter, Mars, are taken through red, green and blue filters. The images are then combined in the lab on Earth and voila! color. Of course there are other filters used: infrared, for example, and if you visit such sites as NASA, you can see the resulting images.

lpetrich
02-16-2010, 09:19 AM
Lux - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Lux)
has a nice list of the brightnesses of various environments.

Saturn is about 9.5 times farther away from the Sun than the Earth is, making sunlight there 91 times dimmer.

So clear daylight there would be about as bright as a very cloudy day here on Earth - a few * 100 lux instead of a few * 10,000 lux.

For how much various materials reflect light, see
Albedo - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Albedo)
and for various celestial objects' albedos or reflectivities, see
Bond albedo - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Bond_albedo)

The Moon has an albedo of about 0.1, close to that of asphalt. However, it looks bright because of contrast.

Art_Sempai
02-16-2010, 09:45 AM
History would be different if Earth had rings like that.

Off the top of head sea navigation would easier with a big visible reference like that in the sky.
Satellites would have to be placed in different orbits.

Hmm...It's the rainbow bridge to Asgard lol.

OMG!...You could project advertising onto the rings with lasers!

small axe
02-17-2010, 01:43 AM
"We're sorry," the Earth ambassador told the two hundred species of the Galactic Council. "But we've changed our minds; Earth doesn't want to join your Community of Worlds."

"Fine," the Galactic Ambassador from Q'weelfarx XII said. "Then give us back the damn planetary rings!"