Originally posted by azureskys
Sorry, but the distance between Collo and Mt. Etna is more than 750km!!! Over such a great distance you can't even see Mt Etna if our planet would be
flat. Imagine that the surface of our planet is curved. The height difference over a distance at about 350km will be nearly 9km. Mt. Etna is more than
Distance from Palermo to Algiers
Distance is 925 kilometers or 575 miles or 499 nautical miles
The distance is the theoretical air distance (great circle distance). Flying between the two locations' airports can be a different distance,
depending on airport location and actual route chosen.
I'm with elevenaugust on this one. Etna is quite a bit too far away to be visible from the OP's location.
As an astrophotographer I have had quite a bit of experience with light pollution. Even the light from a large city (which would be much more light
than Etna is generating, except perhaps during a MAJOR eruption) would not be visible to the naked eye from more than 200 or 300 km away, and we are
talking much further here.
I also specialize in meteors and fireballs, and whilst these can be visible from up to 1000 km away, that is as much because of their altitude
(usually between 50-100 km) as it is due to their extreme brightness in the case of bright fireballs.
Crucially, when they are observed at these distances, to an observer they appear to be VERY LOW above the horizon, and not high up in the sky like the
OP's mystery lights.
Whilst I don't know what it is that the OP saw/photographed, the chances are that it was relatively close - at most 100 km, but probably quite a bit
closer I would guess.
What the OP is seeing can effectively be considered to be "light pollution" (ie light from the ground) since it's been seen for at least a few
different nights in the same part of the sky, and it can not be an astronomical phenomenon since it would be visible over a very wide area, and would
have been reported by now if it was.
Light pollution is only visible in the sky because water droplets/ice crystals/particulates in the atmosphere (specifically the Troposphere) scatter
and reflect light from the ground back to the eyes of someone looking at the sky.
As you can see in the diagram above, the Troposphere only reaches up to about 14 km altitude, and it is here that the vast majority of light is
reflected back to the eyes of an observer on the ground.
My first thought when I saw the OP's photograph was Light pillars
Source: click here
Columns of light apparently beaming directly upwards from unshielded (and wastefully polluting) lights are sometimes visible during very cold
weather. Plate shaped ice crystals, normally only present in high clouds, float in the air close to the ground and their horizontal facets reflect
light back downwards.
The pillars are not physically over the lights or anywhere else in space for that matter ~ like all halos they are purely the collected light beams
from all the millions of crystals which just happen to be reflecting light towards your eyes or camera.
Artificial light pillars can be much taller than their natural counterparts because rays from the lights are not parallel and plate crystals with
small tilts can still reflect them downwards. The crystals producing the pillars are roughly halfway between you and the lights.
When ice crystals float in the air around you, pillars (and other halos) can even be seen around streetlights a few metres away.
I'm not so sure they are light pillars since they are not a frequent occurrence in the part of the world where the OP is, but it may be a possibility.
More likely I suspect would be some kind of a search light shone in the sky as elevenaugust suggested.
edit on 14-4-2013 by FireballStorm
because: ran out of room
edit on 14-4-2013 by FireballStorm because: formatting