How far is up?

[JLSE]

Good thing NASA requires all of its explorers to have x-ray vision

 

[RA_pierce]

Ace explained it, It's not that light is invisible in a vacuum, it's just that the beam is. The dot from a laser would be perfectly visible, but the beam would not because there are no particles for the beam to reflect off of.

I doubt a laser will be visible on the moon. Maybe a green MegaWatt class laser could do it, but since the moon is lit up, shining a 300mW laser on it (even with 0mRad divergence) would be like shining a 300mW laser on a white water tower a mile away in direct sunlight. The dot would be overpowered by the reflection of the sunlight, and the distance is too great for the dot to be noticeable. The surface of the moon is not a mirror surface either, so the laser would be diffused by the surface so very few photons would make it back to earth.
How long would it take a beam of light to reach the moon and back anyway?

 

[Spyderz20x6]

Yup, it all depends on divergence. If you have a 0 Mrad laser and a telescope, you'd be able to see the dot on the moon, but by the time the laser gets to the moon, the dot would be around 10M big!

How long would it take for the dot to get to the moon?

 

[JLSE]

There has been measurements taken with laser for the distance between us and the moon, accurate down to inches. There is also some research done with laser and the Aurora Borealis, below is the only link I could find with a pic of a beam in space. Also just cause its space, it doesn’t mean there is no dust. We all have cosmic dust on us, and around us. Anyway here is the link-


http://images.search.yahoo.com/imag...ace&type=JPG&oid=21195f01912a34cc&no=14&tt=88

Don’t forget, there is a dark side of the moon, which would aid in it's visibility

 

[JLSE]

[quote author=Things link=1209442719/0#5 date=1209447381]Yup, it all depends on divergence. If you have a 0 Mrad laser and a telescope, you'd be able to see the dot on the moon, but by the time the laser gets to the moon, the dot would be around 10M big!

How long would it take for the dot to get to the moon?[/quote]


Average Distance from Earth: 238,855 miles, at 186,000 miles per sec, not too long


or 700 million miles an hour

 

[Razako]

What would someone on a mountain 5 miles away see at night if you pointed a 300+mw green straight at them? It would look strange seeing a huge green circle moving around on the mountain for no apparent reason. UFO sightings anyone?

 

[JLSE]

probably not much if you hit em in the eyes, lol

 

[GooeyGus]

There has been measurements taken with laser for the distance between us and the moon, accurate down to inches. There is also some research done with laser and the Aurora Borealis, below is the only link I could find with a pic of a beam in space. Also just cause its space, it doesn’t mean there is no dust. We all have cosmic dust on us, and around us. Anyway here is the link-


http://images.search.yahoo.com/imag...ace&type=JPG&oid=21195f01912a34cc&no=14&tt=88

Don’t forget, there is a dark side of the moon, which would aid in it's visibility

I cant tell if that pic is space, or if its actually just shooting from earth into the sky, but with an intense "fish eye" lens on the camera. But I think its a lens...

 

[Murudai]

Read this: http://science.nasa.gov/headlines/y2004/21jul_llr.htm

Now, find the specs of one of those lasers and try to make it handheld (I'll give you a cookies if you can do it).

 

[Switch]

Doesn't that kinda prove that the moonlanding was real? :-/

 

[Murudai]

*smacks* it was real.

I mean what, so all the scientists who have used the MANY equipments left there are in on the conspiracy too? And thus lying about their results (Rule 1 of science no noes) all this time?

Either the moonlanding was real, or there is a HUGE conspiracy involving half the worlds astronomers and astrophysicists

...

If I don't come back here, it means the conspirators silenced me, and then it is up to YOU to spread the truth!

 

[usakicksass]

While reading one of Carl Sagans books he said a laser beam was shot at one of those omnidirectional reflectors left by astronauts on the moon. He said that by the time the beam returned to Earth there was the equivalent of 6 photons of light.

 

[JLSE]

*smacks* it was real.

I mean what, so all the scientists who have used the MANY equipments left there are in on the conspiracy too? And thus lying about their results (Rule 1 of science no noes) all this time?

Either the moonlanding was real, or there is a HUGE conspiracy involving half the worlds astronomers and astrophysicists

...

If I don't come back here, it means the conspirators silenced me, and then it is up to YOU to spread the truth!

I would like to see the apollo 11 missing footage. The only conspiracy may be that of which was never shown. Any George Noory or Art Bell fans know what im talking about

 

[diachi]

would it not be easier just to have a reciever on the moon that detects the photons and transmits the data back to earth ??

 

[Switch]

would it not be easier just to have a reciever on the moon that detects the photons and transmits the data back to earth ??

that would require batteries :

 

[pullbangdead]

[quote author=Diachi link=1209442719/15#29 date=1209575462]would it not be easier just to have a reciever on the moon that detects the photons and transmits the data back to earth ??

that would require batteries :[/quote]

Or solar panels. We use them on satellites, and Mars, all the time.

Or radioactive decay, like the deep space probes: decay of plutonium (or other elements) generates heat, and thermoelectrics use the heat to generate electricity. Those things have been running since the 1970s, all the way out past Pluto now I believe.