Comments on: NASA shoots the Moon

By: Professor Mayhem

Professor Mayhem — Fri, 01 Oct 2010 15:00:14 +0000

TAKE THAT, MOON!

By: carl lafonge

carl lafonge — Fri, 01 Oct 2010 01:22:00 +0000

@Mapnut. From the angle that the picture was taken the laser appears to reach all the way to the moon. As you move away from the source, it becomes more faint and the fact that the laser stops short of the moon is obvious. It really does look like this. In person you would be able to see the pulsing. In this picture it looks like a beam.

The green laser light is visible as long as there is something for it to bounce off of. In this case it’s molecules in the atmosphere (Rayleigh/Raman backscatter ). Above 100 km or so there isn’t anything for the laser to bounce off of until it hits the moon (or the LRO).

By: forrest noble

forrest noble — Thu, 30 Sep 2010 21:41:33 +0000

“Shooting the moon” more than 60 years ago (before the laser was invented) was rather easy, so I’ve heard

But seriously, this picture is too cool. I’ll take their word for it that it isn’t doctored. As already stated, however, they’ve been shooting lasers at the moon on a regular basis since we first put the reflectors there about 1970.

By: Andy Beaton

Andy Beaton — Thu, 30 Sep 2010 15:11:42 +0000

Yeah, sure, go ahead and laugh. I checked the moon last night and half of it had been COMPLETELY BLOWN AWAY!

By: Mapnut

Mapnut — Thu, 30 Sep 2010 14:12:24 +0000

As with the Milky way photo, I don’t see how those beams can actually be aimed at the moon. How high up does the part of the beam go that we can actually see? Surely the photo isn’t showing the actual beam just before it contacts the moon, 240,000 miles away. If the beams we see are only visible, say, 100 miles up, then they must cross each other and continue in different directions, going nowhere near the moon. Is it a doctored photo? Or did they temporarily aim the lasers so it would look like they’re hitting the moon?

By: Lisha Sterling

Lisha Sterling — Thu, 30 Sep 2010 06:29:15 +0000

Hey, do they have one of these things at UC Berkeley, too? I remember seeing something that looked just like this green laser coming up on the hill, it looked like somewhere near the Lawrence Lab, at Berkeley when I was a student there in the late 90′s.

By: ma

ma — Thu, 30 Sep 2010 01:10:46 +0000

woww this is great following this blog now, love astronomy

By: Moon Town by Steve Ogden - Real Life VBL

Moon Town by Steve Ogden - Real Life VBL — Wed, 29 Sep 2010 23:53:32 +0000

[...] Town’s VBL, but lookit NASA GO! The huge nerds extremely cool guys at NASA can be seen at the Bad Astronomy blog using lasers to measure the distance between Earth and things that are very far away. And [...]

By: Gonçalo Aguiar

Gonçalo Aguiar — Wed, 29 Sep 2010 23:28:39 +0000

When I first saw this picture I thought that the first laser was being reflected back from the moon! How silly am I!?

By: Mary

Mary — Wed, 29 Sep 2010 23:21:37 +0000

I love my green laser for pointing out constellations at public star parties, helping others locate specific objects, using instead of a finder scope on my telescopes….
Mine is a 5 milliwatt. That is the highest I will use. From the information I have, our natural blink reflex will protect one’s eyes if by some accident or stupidity it is pointed at someone. Higher than 5mW poses increased danger of potentially permanent damage, and for me, is not worth the risk. The 5mW does not work in a highly light plolluted area, but does work in areas that are not completely dark. Bigger and brighter, in this case, is not needed when 5mW works adequately for small groups under most conditions . They are not to be used at star parties where someone is astro imaging nor near airports as planes are necessarily at low altitudes. In the U.S. it is not permitted to sell lasers for pointing applications over 5 mW. I think the U.K. is limited to 1mW. Canada, as far as I can find, has no specifc restrictions. I actually wish there were as there have been some cases of idiots pointing green lasers at aircraft. If there are too many foolish uses, these lasers could be banned and that would a shame. They are something to be used with consideration and caution. Green lasers are not toys.
See
http://www.laserpointersafety.com/index.html
for great information on green lasers. The section on ‘Effects on Pilots’ and the ‘this photo’ it links to is particularly interesting.
I paid a ridiculous high amount for my first one. Now, they can be purchased for ridiculously low amounts. Unfortunatley, some eBay advertisements advertise them as toys—such as showing how the high powered ones might light a match. There are also some high powered ones for sale from other countries that do not meet North American stasndards.
They are useful educational tools with the potential to be misused.

By: Nekura

Nekura — Wed, 29 Sep 2010 23:19:17 +0000

It’s a good thing the Apollo astronauts thought to installed those laser deflection stations on the moon when they were there.

By: WJM

WJM — Wed, 29 Sep 2010 23:12:28 +0000

The frickin’ sharks are only dangerous when the frickin’ laser beams are on their frickin’ heads.

By: Chris

Chris — Wed, 29 Sep 2010 21:14:11 +0000

Dave,
I work with 10 W green lasers and there are enough dust particles floating around that it makes the laser really easy see. I’m not sure what power they have but even a 1W beam would be powerful enough to see on a dark night.

By: Preparen, apunten… luz… « Pablo Della Paolera

Preparen, apunten… luz… « Pablo Della Paolera — Wed, 29 Sep 2010 21:04:45 +0000

[...] NASA – Observe the Moon NASA shoots the Moon [...]

By: One Eyed Jack

One Eyed Jack — Wed, 29 Sep 2010 20:35:49 +0000

Don’t be such a Nancy.

Friggin lasers on friggin sharks are friggin cool.

By: Ross

Ross — Wed, 29 Sep 2010 20:24:08 +0000

If you want to experience an actual death ray, you need only go to the Vdara hotel pool in Las Vegas:
http://abcnews.go.com/Travel/las-vegas-hotel-pool-sunlight-swimming-tourists/story?id=11739234

By: HvP

HvP — Wed, 29 Sep 2010 19:27:51 +0000

Dave Scruggs,

That’s generally true for red lasers. There are usually enough particulates just generally floating in the air to cause some scattering of any laser except that our eyes aren’t sensitive enough to see it at the low levels that they use. However, you might notice that these lasers are green in color. Shorter wavelengths are more easily scattered by our atmosphere, as you can see by the blue color of the sky on a clear day.

Apparently, there are high power consumer grade hand-held lasers that can be seen by the naked eye under the right conditions.

By: Ken B

Ken B — Wed, 29 Sep 2010 19:27:20 +0000

Charles:

Yes, not only is the return signal extremely diffuse, but there is not a reflector on the other side pointed *directly* back towards the Goddard Space Center. Think about how exact that reflector would have to be positioned to reflect back from the moon!

Actually, the reflectors left by the Apollo astronauts do just that — reflect directly back at the sender.

http://www.lpi.usra.edu/lunar/missions/apollo/apollo_11/experiments/lrr/

And I hope that no one at Goddard left a dirty sock nearby.

By: Steve VanDevender

Steve VanDevender — Wed, 29 Sep 2010 19:15:13 +0000

“We know the speed of light very accurately . . . .”

Since 1975, we know the speed of light exactly, because it became a defined constant rather than a measured value. The speed of light is now defined as 299,792,458 meters per second with no uncertainty. Some time before that the second was defined as “9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom”, and now the meter is derived from those two constants.

By: Dave Scruggs

Dave Scruggs — Wed, 29 Sep 2010 19:13:08 +0000

Ok, I’m a bit confused. (Not hard to do any more, I have teenage children.) The lasers are visible on what looks like a clear night. They shouldn’t be visible at all with no smoke or dust or whatever to reflect off of. So what’s going on here?

By: Nemesis

Nemesis — Wed, 29 Sep 2010 18:50:29 +0000

I think the Moon is doing the shooting- two lasers: a preemptive one towards the observatory and one at Dick Cheney.

By: Chris

Chris — Wed, 29 Sep 2010 18:49:51 +0000

Are they sure they aren’t going to blow up the moon?

By: Kevin

Kevin — Wed, 29 Sep 2010 18:33:23 +0000

Heck, anyone can fire a laser at the reflectors up there.

They did it on The Big Bang Theory last year.

By: Rhacodactylus

Rhacodactylus — Wed, 29 Sep 2010 18:30:42 +0000

Finally, now if we can just get some fricken’ sharks with some fricken’ laser beams on their heads we’ll be all set

By: DrFlimmer

DrFlimmer — Wed, 29 Sep 2010 18:20:04 +0000

Clearly defeated in their attempt to destroy the galaxy with a laser, NASA sets its sights somewhat closer and tries to destroy the Moon:

Hmm… but that was ESO’s VLT that shot the galactic center and not NASA….. just a little nitpick