The moon.

[RB astro]

I moved this thread to the "other" section of the forums.

-Alex

Good work Alex.

:beer:

 

[Lifetime17]

Hi,
Really the moon has been battered with asteroids for millions of years, a beam shooting at it will not make any difference. By the way there is a Cherrry moon out tonight full and red check it out ..

Rich

 

[NightExplorer96]

Good work Alex.

:beer:

Thx!

-Alex

 

[Benm]

It's an interesting idea, but not really that feasbile:

There are retroreflectors on the moon which are still used to measure the exact distance and such. As far as i know they use very narrow wavelength sodium lasers to bounce back the light, and only a countable number of photons are actually received back.

Lets ignore those retroreflectors for a bit (hitting one is very difficult and requires extremely low divergence lasers) and just presume people point there lasers at the moon on a new moons night. Lets say 1 million people join in this event, all of them manage to hit the moon on some random point, and they have 1 watt lasers each (on average).

The part of the moon we can see or hit with lasers is about 10^7 km2, not counting the fringes where you nearly miss it. So blasting it with a megewatt of total laser light would light up the surface by 100 mW/km2. This is not very much, probably too little to be visible at all.

Just for comparison, the relfected light during a full moon onto earth is in the order of 1 mW/m2, or 1 kW/km2.

So a million people with 1 watt lasers pointing at the moon would still leave it about 10.000 times darker there than a full moon night on earth... probably even too little to find your way when standing on the moon, let alone be enough to be seen from earth.

 

[dden4012]

It's an interesting idea, but not really that feasbile:

There are retroreflectors on the moon which are still used to measure the exact distance and such. As far as i know they use very narrow wavelength sodium lasers to bounce back the light, and only a countable number of photons are actually received back.

Lets ignore those retroreflectors for a bit (hitting one is very difficult and requires extremely low divergence lasers) and just presume people point there lasers at the moon on a new moons night. Lets say 1 million people join in this event, all of them manage to hit the moon on some random point, and they have 1 watt lasers each (on average).

The part of the moon we can see or hit with lasers is about 10^7 km2, not counting the fringes where you nearly miss it. So blasting it with a megewatt of total laser light would light up the surface by 100 mW/km2. This is not very much, probably too little to be visible at all.

Just for comparison, the relfected light during a full moon onto earth is in the order of 1 mW/m2, or 1 kW/km2.

So a million people with 1 watt lasers pointing at the moon would still leave it about 10.000 times darker there than a full moon night on earth... probably even too little to find your way when standing on the moon, let alone be enough to be seen from earth.

Ok so beam expanders and 7w lasers should do the trick :tinfoil:

 

[Rivem]

It's an interesting idea, but not really that feasbile:

There are retroreflectors on the moon which are still used to measure the exact distance and such. As far as i know they use very narrow wavelength sodium lasers to bounce back the light, and only a countable number of photons are actually received back.

Lets ignore those retroreflectors for a bit (hitting one is very difficult and requires extremely low divergence lasers) and just presume people point there lasers at the moon on a new moons night. Lets say 1 million people join in this event, all of them manage to hit the moon on some random point, and they have 1 watt lasers each (on average).

The part of the moon we can see or hit with lasers is about 10^7 km2, not counting the fringes where you nearly miss it. So blasting it with a megewatt of total laser light would light up the surface by 100 mW/km2. This is not very much, probably too little to be visible at all.

Just for comparison, the relfected light during a full moon onto earth is in the order of 1 mW/m2, or 1 kW/km2.

So a million people with 1 watt lasers pointing at the moon would still leave it about 10.000 times darker there than a full moon night on earth... probably even too little to find your way when standing on the moon, let alone be enough to be seen from earth.

I was going more for a social experiment/holiday activity for fun, but yeah you definitely wouldn't see this work since actual moonbounce lasers are of a quality far beyond anything a hobbyist would have. I'd know, it was a topic in a class I took.

 

[Richie89]

This gives me an idea. What if we just had one night at a precise time for each time zone where everybody lased the moon with their most powerful laser. Schedule far in advance for as many people to see it as possible. Would we discover other laser enthusiasts nearby? Would we be alone with distant onlookers fearing UFOs?

This could be the final event of International Laser Day.
(This should probably be May 16)

I'm not gonna lie Rivem, but that sounds like the coolest idea ever!!

 

[Rivem]

I'm not gonna lie Rivem, but that sounds like the coolest idea ever!!

Glad you like it Richie! Now we just need to figure out what else we should do for a laser-related holiday and start promoting.

 

[Alaskan]

I saw a guy shoot a beam at the moon from Florida when I was in Alaska. Man, it was impressive when it shot over head, made a little spot you could clearly see on the surface when looking with a telescope.

Well... I'm really trolling, I suspect this whole thread was made by one, but so funny it's good.

Photo from: http://laserpointerforums.com/f44/150w-space-laser-florida-92111.html

 

[paul1598419]

Yeah, this is pretty silly. And if everyone were to try to hit the moon at the same time, you'd want to do it during a new moon, not full, as the sun's reflected light would wash out any returning photons.

 

[Rivem]

Lets ignore those retroreflectors for a bit (hitting one is very difficult and requires extremely low divergence lasers) and just presume people point there lasers at the moon on a new moons night.

Yeah, this is pretty silly. And if everyone were to try to hit the moon at the same time, you'd want to do it during a new moon, not full, as the sun's reflected light would wash out any returning photons.

The whole point of the new moon is that it's in line with the Sun, and it's only "visible" during the daytime. That's why solar eclipses only occur during new moons. Ideally, ranging the moon would occur with a very particular identifiable wavelength, and it doesn't depend upon the phase that much.


It's mostly done with some form of solid state that's high-powered and/or q-switched. It's usually done with very low divergence 532nm lasers and highly precise aiming systems. Originally, ruby lasers were used. Large aperture telescopes are then used with filters and usually photomultipliers to detect the few photons that make it back.

The sodium line lasers Benm mentions are not used for this. Those are meant for adaptive telescope optics. They work by using a high power 589 dye or DPSS laser to excite a spot in the atmosphere's sodium laser so that the optics can be adjusted precisely to a known source. Read up on artificial guide stars if you're interested.


Everybody's been joking about ranging or simply mentioning it though. My suggestion was to collectively point beams to see if we could spot like-minded people nearby. :crackup:

 

[paul1598419]

No, I get how the ranging is done. I was commenting on the possibility of everyone on earth using a laser pointer (tongue in cheek). A new moon is not visible to everyone on earth at night, but since it subtends an angle of 5 degrees it is still visible to some at night in the northern hemisphere. It is just a gag to consider everyone shining a laser pointer at it would even be measurable, much less visible.

 

[Rivem]

No, I get how the ranging is done. I was commenting on the possibility of everyone on earth using a laser pointer (tongue in cheek). A new moon is not visible to everyone on earth at night, but since it subtends an angle of 5 degrees it is still visible to some at night in the northern hemisphere. It is just a gag to consider everyone shining a laser pointer at it would even be measurable, much less visible.

Yeah. This thread's a bit strange but pretty funny. Can't really tell how serious some of the participants are though.:undecided:

As for the true new moon, it'd only be visible towards the poles or during dusk/dawn, so it really wouldn't help. Such a small group could get a good view, it's even less feasible.

 

[Vetttech]

I'm just saying!! LOL! :crackup:

[/URL]http://[/IMG]

 

[Lasing Jake Moon]

Yeah. This thread's a bit strange but pretty funny. Can't really tell how serious some of the participants are though.:undecided:

As for the true new moon, it'd only be visible towards the poles or during dusk/dawn, so it really wouldn't help. Such a small group could get a good view, it's even less feasible.

Your first sentence describes me to a tee. Was a bit :drunk: Not that it usually makes much of a difference. :beer:

 

[Lasing Jake Moon]

I'm just saying!! LOL! :crackup:

[/URL]http://[/IMG]

:crackup: Nice one!