It seems the Luxor Sky Beam in Las Vegas (36.09547N 115.17583W) now uses about twenty 7000-watt xenon bulbs – 350000 lumens apiece? Supposedly the beam from each bulb is a billion candlepower, which would mean each beam is a 1-degree cone if we assume 250000 of the lumens get into it. (I’m now ignoring the problem of defining candlepower in a cylindrical beam.)
The beam is 1.4 miles northwest of the Las Vegas VOR, which is usually? on the flight-plan route for LA-to-Salt Lake City etc flights. So flights at 35000 feet will often pass by, and could well be off the airway due to conflicting traffic or weather. Any reason they would prefer to not fly thru the beam?
Since the beam only hits the bottom of the plane, would the pilots even be able to tell when they’re in the beam?
How about passing above it in a light plane a few thousand feet above the ground? No rule against it? Aside from the birdstrike worry, any reason to not do it? (As I recall, the sun directly overhead produces around 125000 lux, matching the Luxor if you’re 400 meters above it.)
What would it look like from the International Space Station passing thru the beam? A 1-degree cone, so four miles wide, so they’re in it for 0.8 second or less. Would it seem to snap on, full brightness, then snap off 0.8 sec later? Or with imperfect reflectors and whatnot, will it appear more gradually? How dazzling would it be? If they want to, can they predict when their orbit will pass thru that four-mile target? (Come to think: how accurately vertical is the beam?)
How far does the beam extend? I ask because of what I perceived in a recent trip to Paris. The Eiffel Tower has a powerful spotlight at the top, but the beam it casts does not appear to continue indefinitely. Instead, it cast a discrete beam, similar to a light saber. In my ignorance, I expected a spotlight beam to gradually spread out and fade, rather than end abruptly.
I did not readily find photos of the entire Luxor beam, to see if it appeared to act similarly.
You only see a light beam when there’s something in the path to scatter it. And there tends to be more of that closer to the ground than further up. I’m guessing that what looked to you like the end of the beam was just a height where the air pollution above Paris radically decreases.
Not sure if this is relevant but as a kid, I would take a flashlight outside and point it straight up. I was amused that I could see the light reflecting off the clouds.
The lights on the Eiffel Tower shine horizontally though, yet the beams do seem to end at some point. I suppose that might have more to do with our eyes, as there is no reason that the reflection from particulars in the air would stop.
OK, I hadn’t clicked through to the video there before. From seeing the video, one of two things is happening with the Eiffel beams, and I can’t tell from the video which it is: Either the beams are aimed slightly downwards, and the endpoints are where they hit the ground, or they’re perfectly horizontal, and the “endpoints” are an infinite distance away, and end at the perspective vanishing point.
They avoid it. The approach and takeoff from both the NNE/SSW and E/W runways at McCarran Harry Reid Airport are well away from a direct path over the Luxor, so they can see it, but don’t have any reason to fly over it. The pilots would be blinded flying over it and since it’s not necessary, they don’t do it.
When the inhabitants of GJ 1002b arrive in a few years, they’ll inform us they found us because of the bright-ass light we’ve been shining at their capital city for the last 10,000 cycles.
As best I can recall, they seemed to be aimed somewhat downward, but it may have been the perspective. The visible beam seemed to end at a discrete point - well above the ground. They certainly did not light up objects on the ground. I suppose your earlier point of about an air pollution layer is possible.
I do not know much of anything about the physics involved. I do know enough that photons continue essentially indefinitely unless absorbed by matter. The appearance of the Eiffel beams was strikingly unusual to myself and my wife. Like I said, they looked like light sabers.
Please explain. If the beam is aimed straight up, at what angle would the plane have to fly for the beam to be directed into the pilot’s eyes? I’m sure there is something obvious I am overlooking…
If you want me to explain the physics of light travel, I’m a bit out of my element. The link I provided noted that they have a warning system before it is turned on so that pilots aren’t surprised by it. I do know that if I take a super strong LED and point it at something just in front of me, such as smoke, bugs, etc., it will be very bright, even though I’m not pointing the light beam at my face.