Karmakaze Posted November 20, 2009 Report Share Posted November 20, 2009 This is a nice visual aid if you're designing a settled ringed planet. (found via a post on metafilter. Also of interest, this comment about using the rings like a sextant. And some side debate about whether the light absorption would have prevented or retarded human development.) Quote Link to comment Share on other sites More sharing options...
Cancer Posted November 20, 2009 Report Share Posted November 20, 2009 Re: Hypothetical Astronomy: The Rings of the Earth scooped. Quote Link to comment Share on other sites More sharing options...
dmjalund Posted November 21, 2009 Report Share Posted November 21, 2009 Re: Hypothetical Astronomy: The Rings of the Earth earth, being a lot closer to the sum would have two effects. 1) ice would melt - the rings would have to be made out of silicon, carbon or iron 2) even if you ignore the above, the rings would look brighter than they do orbiting saturn Quote Link to comment Share on other sites More sharing options...
Doc Posted November 23, 2009 Report Share Posted November 23, 2009 Re: Hypothetical Astronomy: The Rings of the Earth I read once that the moon, wich is slowly precessing away from earth (3,8 cm a year, if I'm not mistaken) could eventually collapse under gravitational stress and form actually form a ring around the earth (in one or two billion years or so), but I didn't manage to find the document again... Quote Link to comment Share on other sites More sharing options...
dmjalund Posted November 23, 2009 Report Share Posted November 23, 2009 Re: Hypothetical Astronomy: The Rings of the Earth if the moons orbit increases, doesn't the stress get LESS? Gravity does reduce with distance after all (an inverse square law and all that) Quote Link to comment Share on other sites More sharing options...
TSandman Posted November 24, 2009 Report Share Posted November 24, 2009 Re: Hypothetical Astronomy: The Rings of the Earth Aye! Tidal forces are stronger the nearer you are... Quote Link to comment Share on other sites More sharing options...
Doc Posted November 24, 2009 Report Share Posted November 24, 2009 Re: Hypothetical Astronomy: The Rings of the Earth if the moons orbit increases' date=' doesn't the stress get LESS? Gravity does reduce with distance after all (an inverse square law and all that)[/quote'] Aye! Tidal forces are stronger the nearer you are... I know; i don't remember why it was supposed to be destroyed... Anyway, whith another search, I wasn't able to find the document back, but I found this instead: The Moon is gradually receding from the Earth into a higher orbit, and calculations[3][4] suggest that this will continue for about fifty billion years. By that time, the Earth and Moon will become caught up in what is called a "spin–orbit resonance" in which the Moon will circle the Earth in about 47 days (currently 29 days), and both Moon and Earth will rotate around their axes in the same time, always facing each other with the same side. Beyond this, it is hard to tell what will happen to the Earth–Moon system, considering that the Sun is expected to become a red giant in approximately five billion years. http://en.wikipedia.org/wiki/Orbit_of_the_Moon#Tidal_evolution_of_the_lunar_orbit I suppose it was all bullock, then. Quote Link to comment Share on other sites More sharing options...
Cancer Posted November 24, 2009 Report Share Posted November 24, 2009 Re: Hypothetical Astronomy: The Rings of the Earth I've read the "moon will spiral back in" claim also, but it was long enough ago that I don't recall the timescales. Once you get to the Earth & Moon in tidally-locked spin-orbit synchronization, that's a minimum-energy configuration. But if you continue to lose kinetic energy out of the system (to tidal effects due to the Sun, for instance) then the loss of energy causes the Moon to move deeper into the potential well, that is, it comes back closer to the Earth, and the rotation rates of both Moon & Earth adjust to keep the two locked. Run that to completion, and the Moon will eventually cross the Roche limit and get torn apart. FWIW, the last computations I recall reading indicate that the Earth-Moon system will survive the Sun's red giant phase, albeit with a larger orbit (because the Sun will lose a lot of mass, gently, which reduces the gravitational binding of all the planets). Mercury and Venus will be engulfed and destroyed, but if the evolutionary scenario is correct then Earth will survive. Now, it'll have been sterilized by the large increase in solar energy input, and some other geological effects that are coupled to that, but it'll still be there in 6 Gyr. Quote Link to comment Share on other sites More sharing options...
dmjalund Posted November 24, 2009 Report Share Posted November 24, 2009 Re: Hypothetical Astronomy: The Rings of the Earth I vote we migrate to the outer solarsystem Quote Link to comment Share on other sites More sharing options...
Lawnmower Boy Posted November 24, 2009 Report Share Posted November 24, 2009 Re: Hypothetical Astronomy: The Rings of the Earth Count me out. I hate moving. Quote Link to comment Share on other sites More sharing options...
Zeropoint Posted November 25, 2009 Report Share Posted November 25, 2009 Re: Hypothetical Astronomy: The Rings of the Earth But, the Earth is where I keep all my stuff! Quote Link to comment Share on other sites More sharing options...
Doc Posted November 25, 2009 Report Share Posted November 25, 2009 Re: Hypothetical Astronomy: The Rings of the Earth But think about it: the rings of Saturn in the sky! Io's electric arc to Jupiter! Titan's orange sky! Europe's underworld ocean! Uranus' aquamarin... heu... everything! The outer solar system is your's to discover! (check out with your travel agent to see our outstanding offers on permanent or semi permanent move to the newest colonies and get the chance to be thrown into Jupiter's liquid metallic hydrogen core when you die FOR FREE!!!!!!!!) Sign now! (as this forum doesn't permit size 2 letters, you'll have to see on our website if you want to read this part of the contract...) Quote Link to comment Share on other sites More sharing options...
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