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Author Topic: What would happen if the Earth-facing side on the moon were like a mirror?  (Read 1633 times)

Offline ManOfZinc

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Hi all,

New to the forum and hitting you up with a question already! :)

I'm writing a short scifi piece and I need some thoughts on the possible side-effects of having a moon where the facing side is completely covered in reflective material.

In my philosophy, a combination of earth-shine and sunlight would mean the moon is pretty-much in a constant state of being full and a lot brighter than a regular full moon would be under non-reflective circumstances.

Forgetting the "moon madness" psychology of it, what are the other possible side effects of this? Would this have any impact on, say, the tides? Vegetation growth? Would the whole mass of the moon be more susceptible to a photon impact "push", like a solar sail?

I acknowledge by ignorance in this, and seek your sage wisdom.
Regards,
MoZ
« Last Edit: 14/06/2012 08:41:18 by chris »


 

Offline CliffordK

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Re: The Mirror Moon?
« Reply #1 on: 11/06/2012 16:54:43 »
Our moon slowly orbits around the Earth. 
When it is on the sun side of the Earth, it is called a "new moon", and is not visible at night, or gives a small sliver of reflected light.

When the Earth is between the sun and moon it is viewed as a full moon.

Look up Lagrangian Points.  If a moon happened to be in the L2 Lagrangian point, then it would be a constant full moon.  It may frequently have eclipses, but it would remain bright due to the distance from the planet which would allow it to continue to be illuminated by part of the sun.

The Planet would continue to spin, and so the moon and sun would rise and fall, but one would be visible essentially all the time, half a day out of phase.

One issue is that the moon is a sphere. 
That means that when light hits it, the light is reflected in essentially all directions.  Thus, the energy reaching back to the planet is lower than that striking the moon. 

You may get some light, but little heat, and it will still be far less from the sun.

Also, keep in mind that L2 is quite far from the planet, thus a moon the size of ours would appear significantly smaller.

As far as tides...
I believe New Moon and Full Moon give the highest tides.  So, with the moon stuck in L2, Full moon, the tides would be higher, but also fairly uniform, twice a day.  However, the tides are also dependent on the gravity from the moon.  So, if the moon is twice as far away, the tides would be much lower unless the moon was actually also much larger (like a binary planet combination).
« Last Edit: 11/06/2012 17:28:52 by CliffordK »
 

Offline ManOfZinc

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Re: The Mirror Moon?
« Reply #2 on: 12/06/2012 09:05:40 »
Right, I think I understand what you're saying. Unless the moon was stuck in stationary orbit, we are always going to see phases of the moon regardless of its albedo?

So assuming the moon is NOT in a Lagrange point and it was coated in, for instance, super-reflective talcum powder, the idea that earth-shine would give us a full moon "constantly" is still false because of its relative position to earth?
 

Offline CliffordK

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Re: The Mirror Moon?
« Reply #3 on: 12/06/2012 09:18:06 »
Perhaps you could make the planet super-bright & super-reflective to reflect from the sun to the planet to the moon, and back to the planet.

With each step in the reflection being on a sphere rather than a flat surface, more energy is lost.

However, our eyes are designed to see contrast.  So, even if the "dark" portion of the moon was visible, we would see the contrast between the light and the dark, and still see the moon phases.
 

Offline RD

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Re: The Mirror Moon?
« Reply #4 on: 12/06/2012 12:19:16 »
I'm writing a short scifi piece and I need some thoughts on the possible side-effects of having a moon where the facing side is completely covered in reflective material.

Orbiting reflectors are a bit more feasible ... https://en.wikipedia.org/wiki/Solar_mirror#Space_reflectors_for_night_illumination 


... what are the other possible side effects of this?

If you could banish night with reflectors, animals and plants would be deprived of the primary zeitgeber,
e.g. they wouldn't "know" what season of the year it was, as seasonal changes, (e.g. fruiting / hibernation) are triggered by changes in day length.


Forgetting the "moon madness" psychology of it ...
you're right to forget about it ... https://en.wikipedia.org/wiki/Lunar_effect
« Last Edit: 12/06/2012 12:42:14 by RD »
 

Offline ManOfZinc

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Re: The Mirror Moon?
« Reply #5 on: 12/06/2012 15:42:02 »
Forgetting the "moon madness" psychology of it ...
you're right to forget about it ... newbielink:https://en.wikipedia.org/wiki/Lunar_effect [nonactive]
Yes, totally. But don't forget humankind's tendency to, you know, be utterly dumb in its herd behaviour and superstition. All they need is the excuse...

Thanks, chaps. Troopers.
 

Offline syhprum

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If the moons surface was very reflective and spherical the Moon would appear as a very small bright object, this effect specular reflection is sometimes apparent in weather pictures when the Sun reflects in the ocean.
 

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