Unusual Phenomena

[Jetset320]

I'm not sure if this is the correct forum, but I'm sure that there is some 'technical' explaination.

A couple of nights ago I was flying south out of BHX. It was a clear night with some scattered cloud and most importantly it was full moon.

When flying directly abeam the moon (i.e. the moon on my left shoulder), I saw a bright light on the ground that attracted my attention. By the time I focused it had gone, but a few seconds later, I saw it again, always in a line between me and the moon.

We kept the same heading for a long time, so for over 15/20 mins this phenomena continued every few seconds. It was as if someone was shining a huge spotlight on the ground for 2 or 3 seconds at a time. The light would light up factory roofs, curves in roads, rivers/streams etc.

It was so strange that I called the F/O to have a look, just to put my mind at rest that I am not seeing things!

I have actually seen this happen on 2 other occasions, always with a full moon, so I am sure this is the cause, but I have no idea of the physics involved.

Since I've seen it so infrequently I think it requires that the full moon is directly abeam, and about 45 degrees above (not too high). But how does this happen? Has anyone else seen it?

[wingman863]

I don't think I've seen what it is you're talking about but it sounds like the illuminated surfaces were at the right angle to reflect the light in your direction. When you were passing a surface which was at the right angle, the light would be reflected more so than when it hit other surfaces.

Maybe.

[Mad (Flt) Scientist]

Not entirely clear whether it "went away" every time you looked at it, or just the first time?

That (at least) could be due to the fact that we actually have better ability to pick up faint light in our peripheral vision; hence sometimes you can see a comet, say, out of the corner of your eye, but cannot see it directly.

Doesn't explain the apparent 'spotlight' effect, but might explain the on/off behaviour.

[Jetset320]

The best description I can give of the light is similar to flood lit football pitch, though probably three or four times the footprint. Not a normal ray of moonlight at all. A very bright 'spot' of white light.

The light, which had no beam of course but only lit up the ground, would move very fast along the ground (at our speed), and light up a factory or two in an estate for 2/3 seconds, for example. Then it disapears for about 10 seconds or so, and reappears lighting up a bend in a road, seeming like a high-speed-train. Quite spectacular really.

I imagine that it is some sort of reflection of the moon, but I have difficulty with some aspects of that theory, namely why the light comes and goes. Also why is it white light (neon-like) and not yellow light, and how come it is so bright? and lastly why is it so unusual?

[ABO944]

I have witnessed this myself !

Last year around this time, flying from Faro to Exeter. It was during the climb, must have been around 20,000 feet or so.

Full moon, directly on my right hand side, and whilst looking down on the ground I could see what looked like a spotlight being shon on the ground.

Rivers, fields, trees, buildings all apeared as if it was daylight for a second or so, and this continued for quite a while (probably the same, around 15-20 mins) then stopped!

Was really strange, but must be some sort of reflection from the moon ???:confused:

[XPMorten]

Moon light reflecting off the aircraft and onto the ground??

M

[RatherBeFlying]

The moon is an inefficient, but quite large reflector of sunlight.

When low on the horizon, the moon appears yellow because of atmospheric effects on the spectrum as the moonlight has a longer passage through the air -- as happens with sunlight at sunrise and sunset.

Once the moon is well above the horizon the passage through the atmosphere is much shorter and the light is more white.

[av8boy]

My first thought was “opposition effect,” but I believe that only occurs directly opposite the light. In other words, if the moon was high off your left, then you’d witness the opposition effect low on your right like a spotlight. It happens because you’re in line with the light source and the stuff that is illuminated on that axis hides its own shadow. It makes that spot look brighter and the surrounding area look darker. If I’m understanding the situation, the light appeared on the ground in the direction of the moon, so opposition effect doesn’t seem to be the answer.

My second thought is that I’m somehow on the right track but don’t have time to give it much thought at the moment! Perhaps something like specular reflection, but I thought that that only happened with very reflective surfaces. Then again, maybe you’re talking about very reflective surfaces…

Can you guess at where you saw the light on the ground… the moon-earth-eye angle?

Dave

[chrisN]

How about /moon - window glass in plane - spot on earth/ angle - is that about equal? Or is there some other reflective surface on the aircraft that could cause it?

Alternatively (though I think it was excluded by a previous posting), I have certainly seen during daylight the appearance and disappearance of the sun's reflection in standing water, which was otherwise invisible from flying height until it lit up.

Chris N.

[DubTrub]

Possibly an Iridium flare (http://www.heavens-above.com/iridium.asp?)? Although I wouldn't have thought the light refelcted from the ground would be bright enough to see

[Jetset320]

The light was moving on the same side of the moon, i.e. between us and the moon.

It appeared during climb (and cruise) so I do not think that the angle is that super critical.

I am very surprised that this phenomena has not been noticed by many more. One possible reason for this is that the bright light appears slightly below the line of sight when sitting normally in a cockpit seat.

As it appears below and slightly towards the aircraft, perhaps it is missed by so many because, besides the proper angle with the full moon, as well as traveling 'parallel' to the moon, you would have to put your head close to the window to look below to see the light, which only shines occasionally anyway.

I believe it shines occasionally because it must shine on certain surfaces only. Which brings me to another question.......would someone on the ground see the same light?

[Localiser]

Nothing so exciting sorry...

All last week there was a laser light show every evening from Kingfisher shopping centre in Redditch. Quite a few people reported seeing such lights, including the local Police getting numerous UFO reports!

If you don't know it, Redditch is fairly close to the 'GROVE' waypoint. You fly over it on a right base for runway 15 or with a departure involving a left turn out from runway 33.

Hope this puts your mind at rest!! :8

LOC

[Jetset320]

Definately not laser beams.

For starters laser beams light upwards, whilst these 'spotlights' shone downwards.

Secondly they were visible (peridically once at a time) all the way from Milton Keynes down to the South Coast, always abeam our position in line with the moon, so surely not being emmited from a specific ground location.

There is nothing extraterrestrial about it, but probably a natural phenomena which occurs every time there are set requirements present.

[RatherBeFlying]

Time for a bit of geometry and optics:[list=1] There is a triangle between your eye, the moon and the reflecting spot on the Earth's surface
The sum of angles in a triangle = 180 degrees
The angle at the moon is something close to 0
Looking down say 10 degrees makes the angle at the Earth's surface close to 170 degrees
A ray reflecting from a "flat" surface meets and leaves the surface at equal angles
Those angles would be approximately 5 degrees, actually quite close to half the angle down from the viewpoint -- cockpit, mountain top, tower...
[/list=1] Those who have better maths recall can apply height above the ground and Earth curvature to determine the position of a tangential reflecting spot.

The size of the moon and atmospheric diffraction will yield a reflecting spot of considerable area as well as a small spread of angles as rays from different areas of the moon radiate and merge with other rays.

[PleaseSayAgain]

Maybe it was something you would find at this site:

http://www.sundog.clara.co.uk/atoptics/phenom.htm

Awesome site, have a look, everyone!:-)

[Localiser]

Sorry my mistake. I just thought it could have been an explanation!