NoUFO
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Simulation: If Other Planets Were As Close As Moon

Sat May 11, 2013 7:31 pm

Mars and Neptune look cool, Saturn too, but a bit intimidating as well.

http://twistedsifter.com/2013/05/if-...ere-as-close-to-earth-as-the-moon/
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kc135topboom
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RE: Simulation: If Other Planets Were As Close As Moon

Sat May 11, 2013 10:24 pm

Well, we would never see it. First, Saturn is all wrong, we would be inside most of the rings. Second, and most important, is with any of the gas giants, gravitational forces would tear Earth apart. Earth would tear Mars apart because of our stronger gravity, Earth and Venus, both being about the same size, would probably orbit each other in a binary mini-system within the solar system.
 
Oroka
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RE: Simulation: If Other Planets Were As Close As Moon

Sat May 11, 2013 11:59 pm

I dont think anything would get torn apart, the bigger body would win the battle and the smaller body would end up in orbit, or flung off into a new orbit of the solar system or even out into interstellar space. Earth + a gas giant would be the worst combo though, due to the large quantities of water on Earth. The gas giant's gravity would drag massive tides across the planet, going hundreds of kilometers inland.

Large moons (and small ones) like Ganymede and Titan were most likely smaller planets that got scooped up by Jupiter and Saturn as they moved farther out into the solar system. That said, it is believed that the asteroid belt is the remains of a rocky planet that got shredded by one of the gas giants passing through.
 
NoUFO
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RE: Simulation: If Other Planets Were As Close As Moon

Sun May 12, 2013 1:21 pm

Quoting KC135TopBoom (Reply 1):
with any of the gas giants, gravitational forces would tear Earth apart.

Well, that's what the article says.

Quoting KC135TopBoom (Reply 1):
Earth would tear Mars apart because of our stronger gravity

Since Earth doesn't tear our moon apart, how could Earth possibly tear a bigger planet apart?
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connies4ever
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RE: Simulation: If Other Planets Were As Close As Moon

Sun May 12, 2013 1:57 pm

Quoting NoUFO (Reply 3):
Quoting KC135TopBoom (Reply 1):
with any of the gas giants, gravitational forces would tear Earth apart.

Well, that's what the article says.

There's an article ? I see a bunch of visualisations is all.

Quoting NoUFO (Reply 3):
Quoting KC135TopBoom (Reply 1):
Earth would tear Mars apart because of our stronger gravity

Since Earth doesn't tear our moon apart, how could Earth possibly tear a bigger planet apart?

But the g-forces extant in the Earth-Moon system do cause crustal movement to a small degree. Tides are another matter since water is, well, a fluid. Putting Jupiter right next to us would be a different thing. Minimum massive tides and earthquakes. Basically Earth would get "squeezed", at a minimum, by Jupiter. That;'s how the volcanoes n Io operate, for example, but Io is much farther from Jupiter than Jupiter would be from Earth. Might be neat to see in reality, but you'd only get one look at it.
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rfields5421
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RE: Simulation: If Other Planets Were As Close As Moon

Sun May 12, 2013 1:59 pm

Quoting NoUFO (Reply 3):
Since Earth doesn't tear our moon apart, how could Earth possibly tear a bigger planet apart?

The orbit of moons around a planet is an extremely complex balancing act of relative mass, distance and speed.

Change that balance by adding an increase of mass by a factor of over 10 would upset that balance. Mars with its mass could not orbit the Earth at the distance and speed of the Moon.

The math simply doesn't work. It would be an unstable relationship, and since the mass of Mars is only 0.107 that of Earth, it would lose the 'battle'.

Of course, it wouldn't be any fun being here on Earth. The changes would probably make Earth unable to support life of any form.
 
NoUFO
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RE: Simulation: If Other Planets Were As Close As Moon

Sun May 12, 2013 3:06 pm

Quoting connies4ever (Reply 4):
There's an article ? I see a bunch of visualisations is all.

And a little text (not a whole article, but there's still text):

"It’s important to note that this is strictly a visual exercise. If a planet like Jupiter were actually as close to Earth as the Moon, its immense gravitation would wreak havoc on our planet. So for the gallery below, please temporarily suspend your disbelief and just imagine how amazing it would be to see a planet like Saturn in such incredible detail."
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connies4ever
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RE: Simulation: If Other Planets Were As Close As Moon

Sun May 12, 2013 3:14 pm

Quoting rfields5421 (Reply 5):
The orbit of moons around a planet is an extremely complex balancing act of relative mass, distance and speed.

Change that balance by adding an increase of mass by a factor of over 10 would upset that balance. Mars with its mass could not orbit the Earth at the distance and speed of the Moon.

The math simply doesn't work. It would be an unstable relationship, and since the mass of Mars is only 0.107 that of Earth, it would lose the 'battle'.

Of course, it wouldn't be any fun being here on Earth. The changes would probably make Earth unable to support life of any form.

Totally agree. With the Earth-Moon system it's relatively cut and dried. Any other satellites Earth has, and there may be some, are so small as to not count. So it's not even a restricted 3-body problem. In the Jovian or Saturnian systems many of the orbits followed by particularly the smaller satellites are unstable.

Quoting NoUFO (Reply 6):
"It’s important to note that this is strictly a visual exercise. If a planet like Jupiter were actually as close to Earth as the Moon, its immense gravitation would wreak havoc on our planet. So for the gallery below, please temporarily suspend your disbelief and just imagine how amazing it would be to see a planet like Saturn in such incredible detail."

Understood. An interesting hypothesising of the view, but it could never happen in reality. The angular momentum issues would be, well, astronomical.  
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GDB
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RE: Simulation: If Other Planets Were As Close As Moon

Sun May 12, 2013 5:14 pm

Quoting rfields5421 (Reply 5):
Of course, it wouldn't be any fun being here on Earth. The changes would probably make Earth unable to support life of any form.

As you probably know, we are only here since the Moon has a stabilising effect on the Earth, quite apart from the tides.
It might well be that on another planet life could evolve without such a satellite like the Moon, doubtful though if really advanced life forms could evolve.
Which may be one reason that though there have been many stars which were like our Sun is now, 1-2 billion years ago, ET has neither phoned nor shown up.
You don't just need to be in the 'Goldilocks' zone around a stable, Sun like star.
 
connies4ever
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RE: Simulation: If Other Planets Were As Close As Moon

Sun May 12, 2013 6:16 pm

Quoting GDB (Reply 8):
As you probably know, we are only here since the Moon has a stabilising effect on the Earth, quite apart from the tides.

Little known factoid: the Sun accounts for about 30% of the tidal action we see. So if there was no moon, we'd still have smallish tides.

If the Moon is moving away now, it obviously was much closer in the far past. Conservative calculations indicate it couldn't have been much closer than about 15,000 km else Earth's gravitational field would rip it apart, based on data about te mechanical of the regolith and mapping of the interior.

Tidal height is proportional to the cube of the distance between bodies, so if the Moon formed, say, 40,000 or so km from us (1-10th current), then the ocean tides would be an awesome 1,000 times as large as they are now. On a planet with a 6hr day. Probably not a good place to be.
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Oroka
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RE: Simulation: If Other Planets Were As Close As Moon

Tue May 14, 2013 2:21 am

Quoting connies4ever (Reply 9):
Tidal height is proportional to the cube of the distance between bodies, so if the Moon formed, say, 40,000 or so km from us (1-10th current), then the ocean tides would be an awesome 1,000 times as large as they are now. On a planet with a 6hr day. Probably not a good place to be.

Great for budding life on a new planet. All that nutrients being stirred up rather than just settling on the bottom. It played a large part in the early evolution of life on this little ball of rock we call home.
 
comorin
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RE: Simulation: If Other Planets Were As Close As Moon

Wed May 15, 2013 2:29 pm

Quoting NoUFO (Thread starter):

Thanks for a great link! That Saturn picture is the stuff of nightmares.    Would the 'planet-light' be as bright as the Moon (unlikely, I think?).
 
connies4ever
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RE: Simulation: If Other Planets Were As Close As Moon

Wed May 15, 2013 3:53 pm

Quoting Oroka (Reply 10):
Great for budding life on a new planet. All that nutrients being stirred up rather than just settling on the bottom. It played a large part in the early evolution of life on this little ball of rock we call home.

Perhaps it might be. But I would wonder about the churn factor - would it be good for proto-life or simple microbial life ? For example, given that the tides wold have to rush in and then out on a 90-minute basis (spring and neap tides for a 6 hour day), the wave velocity would be enormous.

Quoting comorin (Reply 11):
Thanks for a great link! That Saturn picture is the stuff of nightmares. Would the 'planet-light' be as bright as the Moon (unlikely, I think?).

For argument's sake, if Saturn is parked where the Moon currently is, it has the same amount of light incident on it. The average albedo (reflectivity of incident light) for the Moon is 0.12, for Saturn about 0.34. Saturn has about a 30-something to 1 ratio on mean radius, so it's reflective area is around 900 times that of the Moon, coupled with a reflectivity that's around 3x the Moon, then it's going to 'shine' an ENORMOUS amount of light on Earth at 'full Saturn'. It would be extremely bright, perhaps difficult to look at directly.

http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html

http://nssdc.gsfc.nasa.gov/planetary/factsheet/saturnfact.html
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NoUFO
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RE: Simulation: If Other Planets Were As Close As Moon

Wed May 15, 2013 6:17 pm

Quoting connies4ever (Reply 12):

I just posted a link and now I learn something new every day. *tips hat*
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prebennorholm
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RE: Simulation: If Other Planets Were As Close As Moon

Tue May 21, 2013 1:59 am

Quoting KC135TopBoom (Reply 1):
Well, we would never see it. First, Saturn is all wrong, we would be inside most of the rings.

Not accurate. The outermost ring, the E-ring, is at 182,000km radius, less than half of the Earth-Moon distance 378,000km (mean). The E-ring is very faint. What we actually see as the outermost ring is the A-ring at 137,000km.

Quoting KC135TopBoom (Reply 1):
Second, and most important, is with any of the gas giants, gravitational forces would tear Earth apart.

Also not accurate. To be torn apart the minor object has to be within the "Roche Limit" of the major, see http://en.wikipedia.org/wiki/Roche_limit

Jupiter's innermost satellite, Metis, which orbits at 128,000km radius, is very close to, but just outside the Jupiter Roche Limit, and therefore stretched like an egg, or even worse. But Earth-Moon distance is three times greater. Earth would certainly be treated beyond any recognition, but it wouldn't be torn apart.
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Oroka
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RE: Simulation: If Other Planets Were As Close As Moon

Tue May 21, 2013 5:50 pm

Quoting prebennorholm (Reply 14):
Earth would certainly be treated beyond any recognition, but it wouldn't be torn apart.

Being a thinly crusted ball of lava with a giant ball of iron, nickel, and heavy radioactive elements at its core, the tidal forces from a giant would drag a bulge of lava around the planet under the tectonic plates, breaking up the crust and continents, grinding the surface to gravel. Bleeding heat would boil off the oceans, maybe causing a runaway greenhouse effect, possibly turning Earth into a twin of Venus.
 
rtfm
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RE: Simulation: If Other Planets Were As Close As Moon

Tue May 21, 2013 8:02 pm

Quoting Oroka (Reply 15):

Being a thinly crusted ball of lava with a giant ball of iron, nickel, and heavy radioactive elements at its core, the tidal forces from a giant would drag a bulge of lava around the planet under the tectonic plates, breaking up the crust and continents, grinding the surface to gravel. Bleeding heat would boil off the oceans, maybe causing a runaway greenhouse effect, possibly turning Earth into a twin of Venus.

So we're all agree we should just leave Saturn where it is right?    
 
prebennorholm
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RE: Simulation: If Other Planets Were As Close As Moon

Tue May 21, 2013 10:36 pm

Quoting Oroka (Reply 15):
Being a thinly crusted ball of lava with a giant ball of iron, nickel, and heavy radioactive elements at its core, the tidal forces from a giant would drag a bulge of lava around the planet under the tectonic plates, breaking up the crust and continents, grinding the surface to gravel. Bleeding heat would boil off the oceans, maybe causing a runaway greenhouse effect, possibly turning Earth into a twin of Venus.

Yup. That's exactly what would happen. That's what I called "treated beyond recognition".

I wonder if it could be calculated how long time it would take until Earth would become tidally locked in its rotation - like our Moon already is. My wild guess would be that it would happen very very fast, maybe within only a few million years. Then things would calm down a little, and Earth would take the shape of an egg, always pointing one end against Jupiter.

That wouldn't mean that biological processes, as we know them, could be re-established on Earth. Jupiter's insanely strong magnetic field would prevent that.
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flybulldog
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RE: Simulation: If Other Planets Were As Close As Moon

Wed May 22, 2013 5:15 pm

Uranus is a lot bigger than I thought.  
 
Oroka
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RE: Simulation: If Other Planets Were As Close As Moon

Fri May 24, 2013 12:55 am

Quoting prebennorholm (Reply 17):
That wouldn't mean that biological processes, as we know them, could be re-established on Earth. Jupiter's insanely strong magnetic field would prevent that.

I dont know... we are sitting on one of the most powerful magnetic fields in the solar system. While I don't think the magnetic field of Jupiter itself would cause problems, it would keep out even more cosmic radiation. This would bring down the number of genetic mutations in life on the planet, slowing evolution drastically.

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