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living on the far side of the moon

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hordesq

Guest
If you & I lived on the far side of the moon. What could we know of Earth without having ever seen it?
I presume we could determine from celestial observation that our axis of orbit is about 384,000 km away.
Could we also divine the mass of this "Earth" object we have never seen?

Would we be able to receive any electronic signals from Earth?

(There's a new Sci/Fi movie out about a guy living on the far side of the moon in isolation.)
 
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aphh

Guest
Since the Earth-Moon system revolves around it's common center of gravity, with enough precision in their astronomy, folks living on the dark side of the moon could estimate the mass of the object they are gravitationally linked to.

Dark side of the moon would probably be very very silent and shielded place when it comes to electromagnetic waves emanating from the Earth. One option that comes to mind to hear anything from earth is reflection of EM radiation from another body, like Mars or Jupiter.
 
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MeteorWayne

Guest
It's not the dark side, it's the far side. It has 14 days of daylight, and 14 days of night the same as the side that faces the earth.
 
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aphh

Guest
MeteorWayne":2gde7oo3 said:
It's not the dark side, it's the far side. It has 14 days of daylight, and 14 days of night the same as the side that faces the earth.
I know, but being a Pink Floyd fan and a traditionalist, I like this definition way better. Plus it carries a bit of mysticism with it. Like dark matter, dark energy and dark side of the moon. :cool:
 
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chebby

Guest
Considering Apollo craft could not comunicate with earth when behind the moon, I'm going to say no to all electromagnetic observations. Also while in US you cannot listen to Chinese brodcasts, except over the satelite.

I think detecting earth by orbital mechanics would be hard even if moon people had newtonian mechanics. After all, because all observable objects are very far, it would just look like moon has a really long rotational period (27 days) and the fact that it rotates not around its own axes would not be so obious. However if one was to track some object (comet) as it passes by, then it would probably become more obious by observing the error in its location. Then you can work out moon-earth rotational mechanics and that would give you earth mass as well.
 
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kg

Guest
hordesq":jyfw5a9a said:
If you & I lived on the far side of the moon. What could we know of Earth without having ever seen it?...
Would you be able to detect any effects of earths' magnetosphere from the far side of the moon?
 
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CalliArcale

Guest
aphh":2h79eyzw said:
MeteorWayne":2h79eyzw said:
It's not the dark side, it's the far side. It has 14 days of daylight, and 14 days of night the same as the side that faces the earth.
I know, but being a Pink Floyd fan and a traditionalist, I like this definition way better. Plus it carries a bit of mysticism with it. Like dark matter, dark energy and dark side of the moon. :cool:
Read the liner notes to "Dark Side of the Moon", which even says that there is no dark side of the Moon -- their point is that they're singing about a nonexistent place. ;-)

Or a transient place. There is always a dark side of the moon, but it's always changing. Just like the dark side of the Earth. And that has a nifty poetry to it as well.
 
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kelvinzero

Guest
What would someone who actually lived on the far side of the moon call it? and what would they call the side facing earth?
 
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kelvinzero

Guest
tampaDreamer":1fliu6a3 said:
kelvinzero":1fliu6a3 said:
What would someone who actually lived on the far side of the moon call it?/quote]

home
Well, sure.. do you live in the state of home in the country of home on the home hemisphere?

Silly question.. of course you do :)
 
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MetalMario

Guest
kelvinzero":2z2rejxk said:
tampaDreamer":2z2rejxk said:
kelvinzero":2z2rejxk said:
What would someone who actually lived on the far side of the moon call it?/quote]

home
Well, sure.. do you live in the state of home in the country of home on the home hemisphere?

Silly question.. of course you do :)
Also, they are Home Sapiens, with United Home of Home, which is a Homeocracy.
 
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CalliArcale

Guest
"Science Made Stupid" had a wonderful cartoon showing the three basic models of the Universe.

Heliocentric: everything goes around the Sun.
Ethnocentric: everything goes around your nation (the cartoon depicted China).
Egocentric: everything goes around you (cartoon showed the planets and Sun revolving around a smiling person's head).

:)

Regarding what to call the two hemispheres of the Moon.... Astronomers call them the nearside and farside, of course, but residents of the Moon might use different words. I once tried to write a story about a race of creatures living on Titan, Saturn's largest moon. (Unfortunately, I had a problem developing an actual plot, so it went nowhere and was ultimately abandoned.) Titan is also synchronous with its parent, always presenting one face towards Saturn. For the story, I referred to the Saturn-facing side as the "topside", as the native people's ancestors had believed Saturn to stand over them, and believed that the point with Saturn highest in the sky (the point nearest to Saturn) was the highest point on all of Titan. The "lowside" was the side facing away from Saturn.

A really curious situation is Pluto-Charon. They are *mutually* synchronous, so not only does Charon always face on side towards Pluto, but Pluto also faces one side towards Charon. Thus, a person standing on the inward side of either would see the other one fixed motionless in the sky, going through phases while the stars wheeled endlessly by behind it (along with Nix and Hydra, of course, which aren't in the same orbit as Charon and probably are not synchronous with either body -- I would expect that gravitational influences of Pluto and Charon acting on both of them would prevent them from settling into synchronous rotation).
 
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kg

Guest
What about my question about being able to detect earths' magnetosphere from the far side of the moon? Would a person on the far side of the moon be able to detect changes in the solar wind as the moon moved "up wind" and "down wind" from the earth? Also, does the Earths' atmosphere shed any matereal into space the same way Venus does? If so maybe a moon dweller could somehow "sniff" out the Earth.
 
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aphh

Guest
chebby":30v5ggrg said:
Considering Apollo craft could not comunicate with earth when behind the moon, I'm going to say no to all electromagnetic observations. Also while in US you cannot listen to Chinese brodcasts, except over the satelite.
You could still catch an echo of a signal bouncing back from the layers of the athmosphere. When the angle of the waves reaching the boundary between air and vacuum reaches certain value, the wave would not be able to go through the boundary, but would get reflected to the opposite angle where it came from. Indirectly EM waves could be received far away from the direct useful range. Ofcourse this would not apply on the moon, unless the waves bounced back from some object, like Jupiter.

chebby":30v5ggrg said:
I think detecting earth by orbital mechanics would be hard even if moon people had newtonian mechanics. After all, because all observable objects are very far, it would just look like moon has a really long rotational period (27 days) and the fact that it rotates not around its own axes would not be so obious. However if one was to track some object (comet) as it passes by, then it would probably become more obious by observing the error in its location. Then you can work out moon-earth rotational mechanics and that would give you earth mass as well.
Using triangulation over a period of one Earth year would give a large enough baseline, so they might be able to get a clue about the radius of Earth's orbit.

To say for sure would mean math and calculations, and it would be an interesting problem to solve. With unlimited amount of time at hand and not being a lazy person, I'd try it.
 
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MeteorWayne

Guest
Measuring their positions, they would certainly realize that they are orbiting the sun and another object as well, at the same time. It might take a while, after all a few hundred years ago humanity thought the earth was at the center of the Universe, but with brilliant enough astronimers and mathematicians, they's figure it out.

Besides, it's hard to imagine they wouldn't explore the other side of their world, just as we did. Then they'd see this blue white and green BIG planet :)

Though the might call the moon a planet, and the earth a God :) :)
 
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aphh

Guest
I think they are nomads, who live to follow the day/night dividing line. I'm sure anybody could calculate the distance they need to travel each day.

They would go to sleep before the night falls down and wake up early in the night. Then they would need to race to catch dawn, or more like dusk, again.

Following this routine has made them go nuts over time, because if they overslept, they might never catch dawn ever again and would be forced to live in eternal night for the rest of their lives.
 
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hordesq

Guest
MeteorWayne":2gn2gpxs said:
Besides, it's hard to imagine they wouldn't explore the other side of their world, just as we did. Then they'd see this blue white and green BIG planet :):)
The method of our exploration was by BOAT!


These "farsiders" built quite a few but couldn't figure out what to do with them.
After all, they are "lunatics".
 
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