Mirrors On The Moon

[All Seeing Eye]

If we coated the entire Earth facing side of the Moon with Mirrors would it make night time on the Earth a lot brighter? and would it make night time on Earth warmer?

What would be the benefits of this?

Would it be like having a second but smaller sun?

 

[TerriO]

If we coated the entire Earth facing side of the Moon with Mirrors would it make night time on the Earth a lot brighter? and would it make night time on Earth warmer?

What would be the benefits of this?

Would it be like having a second but smaller sun?

What I'd want to know first would be why do it? If we're facing an issue of the global climate getting warmer, why add to that with amping up the reflected sunlight from the moon? You're talking a massive expenditure of energy and labor with no real purpose set forth.

Not necessarily a "what would be the benefits", but more of a "what would be the purpose?" I suppose. Sure, solar power collectors would probably be good for a lunar colony, but getting that power back to Earth would be challenging.

 

[Alpha_Geek]

Have you ever seen a convex mirror used to concentrate light without other optical elements being involved?

 

[All Seeing Eye]

What I'd want to know first would be why do it?

Good question and here are the answers:

1. No more need for street lights all the time at night.
2. Crops, plants and most importantly trees will gain more sunlight than they would otherwise allowing them to grow faster and larger as they gain more sunlight per day.
3. Solar power plants at night can continue to function (although at a much lesser level than daytime of course).
4. Night time especially in Winter won't be as cold.

Sometimes the moon can be so bright it lights up peoples bedrooms through curtains, that's pretty powerful already. So if we were to add full on Mirrors to the entire Earth facing surface the light hitting us would be incredible, especially during a full moon.

 

[Geckothan]

1. Ok fair enough, that's a good thing.
2. Many plants don't like being exposed to light 24 hours a day.
3. That's another good thing.
4. I'm sure there's some disadvantages to this, but I can't think of any now.

 

[Mr. B]

The lunar surface reflects more than enough light now.

 

[Jadzia]

Sometimes the moon can be so bright it lights up peoples bedrooms through curtains, that's pretty powerful already. So if we were to add full on Mirrors to the entire Earth facing surface the light hitting us would be incredible, especially during a full moon.

Our eyes have good action over a wide range of light levels.

There is a difference between power stations and eyes. We only have to "see", while solar power stations are all about energy. Moonlight is really about 1/1000th of the power of sunlight at best. Moonlight is never warm on your face. (Warm = energy)

Mirrors.. if they're flat mirrors, they would reflect light very strongly and make night almost as bright and as warm as day. But getting them reflecting in the right direction (towards the earth) would be a problem because the moon moves all the time, so you'd only get a few of hours of mirrored-sunlight each month as the reflected 'beam' swipes the earth.

Making the moon into something like a mirror ball would fix that, because some mirrors would always be reflecting towards earth, just like if you look at a christmas tree bauble you can always see reflections of the wall lights in your room.

But (and a big but) the light would reflect in all directions, because it's a convex mirror, and what little bit reflects towards earth would be relatively weak, and without doing any calculations I think the total amount of light we'd get would be only slightly more than what we get from a full moon without any mirrors.

 

[All Seeing Eye]

Sometimes the moon can be so bright it lights up peoples bedrooms through curtains, that's pretty powerful already. So if we were to add full on Mirrors to the entire Earth facing surface the light hitting us would be incredible, especially during a full moon.

Our eyes have good action over a wide range of light levels.

There is a difference between power stations and eyes. We only have to "see", while solar power stations are all about energy. Moonlight is really about 1/1000th of the power of sunlight at best. Moonlight is never warm on your face. (Warm = energy)

Mirrors.. if they're flat mirrors, they would reflect light very strongly and make night almost as bright and as warm as day. But getting them reflecting in the right direction (towards the earth) would be a problem because the moon moves all the time, so you'd only get a few of hours of mirrored-sunlight each month as the reflected 'beam' swipes the earth.

Making the moon into something like a mirror ball would fix that, because some mirrors would always be reflecting towards earth, just like if you look at a christmas tree bauble you can always see reflections of the wall lights in your room.

But (and a big but) the light would reflect in all directions, because it's a convex mirror, and what little bit reflects towards earth would be relatively weak, and without doing any calculations I think the total amount of light we'd get would be only slightly more than what we get from a full moon.

The mirrors would hopefully mimic the curvature of the moon and cover 1 full half of the moon (the entire side facing us). If we are capable of seeing the whole moon during full moon (seeing all light reflected from it) then why wouldn't we see all the light reflected from the mirrors?
The Sun is huge and light would therefore be hitting the mirrors from multiple angles and at least some of those angles on every single mirror will reflect the light to Earths surface.

Also Mirrors are so fantastically more efficient at reflecting than moon dust it stands to reason that the new moonlight from the mirrors will be more powerful than 1/1000th of the power of sunlight.

How big is the Earth facing side of the moon anyway? isn't the surface about the same size as Australia or something?

 

[Jadzia]

The mirrors would hopefully mimic the curvature of the moon and cover 1 full half of the moon (the entire side facing us). If we are capable of seeing the whole moon during full moon (seeing all light reflected from it) then why wouldn't we see all the light reflected from the mirrors?

The light is scattered because the surface is matt, and not glossy. So you see light reflected back from all over the illuminated parts. It's no longer a "beam" it's intensity drops inverse squarely with distance. The proportion of light reflected is called the albedo.

Also Mirrors are so fantastically more efficient at reflecting than moon dust it stands to reason that the new moonlight from the mirrors will be more powerful than 1/1000th of the power of sunlight.

I don't think moon dust is that poor a reflector. It's albedo is not that low. It's just that the reflected light is scattered light, so 1 million miles away from it, it looks relatively dull compared to the sunlight.

In appearance, the mirror coated moon would look mostly black and invisible, with a star reflection on it here and there, a little blue dot in the middle where the earth is reflected (most visible at dawn and dusk), and a very bright spot somewhere on it where it's reflecting the sun.

But the total light we'd get from that bright spot would be not much more than an ordinary full moon. I'd expect maybe 2 - 4 times the total energy we get from the full moon now.


edit: I've look up the figure. lunar albedo = 0.12, which means the mirror coated moon would give us 8x the full moon light, which would probably be like average street lighting But I am still guessing the maths there.

 

[Alpha_Geek]

Timmy, do you like to watch gladiator mvies?

 

[Zulu Romeo]

What I'd want to know first would be why do it?

Good question and here are the answers:

1. No more need for street lights all the time at night.
2. Crops, plants and most importantly trees will gain more sunlight than they would otherwise allowing them to grow faster and larger as they gain more sunlight per day.
3. Solar power plants at night can continue to function (although at a much lesser level than daytime of course).
4. Night time especially in Winter won't be as cold.

Sometimes the moon can be so bright it lights up peoples bedrooms through curtains, that's pretty powerful already. So if we were to add full on Mirrors to the entire Earth facing surface the light hitting us would be incredible, especially during a full moon.

Those are interesting points, but the fact is that life on Earth needs the dark night sky in order to continue its normal function, and to have even a lukewarm global light source to disrupt the night sky could have serious repercussions.

The most serious of these is disruption of diurnal variation both among humans and especially in the natural world, upsetting the way animals behave and thus altering the food chain. Plus, there's the noise pollution which will upset wannabe astronomers as well as professional ground-based scientists who will now be more dependent on Hubble and Spitzer (although even then the increased glow of the Sun from the reflective Moon might even make these space telescopes act differently).

Is it also possible for brighter moonlight, sufficient to brighten the night sky, to also increase the ambient outside temperature (in the same way the Sun naturally does) at night through reflection of infrared radiation as well as the visible spectrum? The climate change lobby would have a field day...

And if nothing else, there's just something magical about seeing the Milky Way light up the clear moonlit sky...




Unless of course it's a devious plan to invest in sleeping eye masks and ultra-dark curtains for the less dark night...

 

[All Seeing Eye]

The mirrors would hopefully mimic the curvature of the moon and cover 1 full half of the moon (the entire side facing us). If we are capable of seeing the whole moon during full moon (seeing all light reflected from it) then why wouldn't we see all the light reflected from the mirrors?

The light is scattered because the surface is matt, and not glossy. So you see light reflected back from all over the illuminated parts. It's no longer a "beam" it's intensity drops inverse squarely with distance. The proportion of light reflected is called the albedo.

Also Mirrors are so fantastically more efficient at reflecting than moon dust it stands to reason that the new moonlight from the mirrors will be more powerful than 1/1000th of the power of sunlight.

I don't think moon dust is that poor a reflector. It's albedo is not that low. It's just that the reflected light is scattered light, so 1 million miles away from it, it looks relatively dull compared to the sunlight.

In appearance, the mirror coated moon would look mostly black and invisible, with a star reflection on it here and there, a little blue dot in the middle where the earth is reflected (most visible at dawn and dusk), and a very bright spot somewhere on it where it's reflecting the sun.

But the total light we'd get from that bright spot would be not much more than an ordinary full moon. I'd expect maybe 2 - 4 times the total energy we get from the full moon now.


edit: I've look up the figure. lunar albedo = 0.12, which means the mirror coated moon would give us 8x the full moon light, which would probably be like average street lighting But I am still guessing the maths there.

Na, i'm going to have to disagree on this. If you were to take a football and coat one side in reflective material as reflective as a mirror and then take a big ass spotlight and shine it straight at that football the light will hit it all over and reflect the light in all directions and at all angles. The light isn't being focused on only one spot on the footballs surface, it's hitting everywhere.

The Sun is huge and sunlight is being released in all directions and is not being focused on only a few mirrors on the Moons surface.

Anyway, if we were to put flat mirrors on the surface we could just motorise them to change direction so the light is focused on the Earth.

Plus, there's the noise pollution which will upset wannabe astronomers as well as professional ground-based scientists who will now be more dependent on Hubble and Spitzer (although even then the increased glow of the Sun from the reflective Moon might even make these space telescopes act differently).

Well if the Mirrors had shutters on them we could send a signal for them to close down and stop reflecting now and again.

 

[Jadzia]

reflections are a lot simpler than magnets. You can understand this one by playing with a torch, and compare the reflections from a mirrorball and a football

Anyway, if we were to put flat mirrors on the surface we could just motorise them to change direction so the light is focused on the Earth.

With that addition, you would then have midnight almost as bright and as warm as midday.

But with more deliberate focussing you could have one hell of a solar furnace, and a weapon potential more deadly than an endless supply of atom bombs

 

[All Seeing Eye]

With that addition, you would then have midnight almost as bright and as warm as midday.

yeh, now all we need is the start of the next ice age so we can get this plan into action.

 

[Zulu Romeo]

Plus, there's the noise pollution which will upset wannabe astronomers as well as professional ground-based scientists who will now be more dependent on Hubble and Spitzer (although even then the increased glow of the Sun from the reflective Moon might even make these space telescopes act differently).

Well if the Mirrors had shutters on them we could send a signal for them to close down and stop reflecting now and again.

I think we should check with the Animal Kingdom to see when they're next happy to have a scheduled Lunar Eclipse.... I think their diaries might be busy.

But with more deliberate focussing you could have one hell of a solar furnace, and a weapon potential more deadly than an endless supply of atom bombs

So whoever controls the Moon can hold the Earth to ransom? Eeeeexcellent.

With that addition, you would then have midnight almost as bright and as warm as midday.

yeh, now all we need is the start of the next ice age so we can get this plan into action.

Al Gore would not be amused.

 

[Dayton3]

Countless observatories on Earth would be out of business.

 

[Jadzia]

Countless observatories on Earth would be out of business.

They would still get a few hours of dark skies in each 24 hour period since the moon isn't always at antipodes with the sun.

So for 10 days in each month, the night would still be as dark as it is now.

 

[Zulu Romeo]

Countless observatories on Earth would be out of business.

They would still get a few hours of dark skies in each 24 hour period since the moon isn't always at antipodes with the sun.

So for 10 days in each month, the night would still be as dark as it is now.

Could they afford to stay open for just 10 days of the month though? I can see many going out of business simply because it would be impractical to maintain such equipment if it is going to be used only a third of the usual time.

 

[All Seeing Eye]

How about using tubes filled with mirrors (basically a fibre optic cable type deal) and place them on the sun facing side of the moon EVERYWHERE, these 'tubes' will travel around to the dark side of the moon where they will all focus the sunlight into a single 'tube'. This tube will be capable of movement allowing for all the sunlight to be focused in whatever direction required.

This 'tube' could then focus the sunlight collected from the sun onto a solar sail ship.

Obviously as the moon orbits the Earth it doesn't always work but when it is operational it could be used to push solar sail ships into the outer solar system.

 

[Jadzia]

It's nice to have you back with us ZR. I hope your drive home was enjoyable.