If you have spent as many nights sleeping under the stars as I have (literally years) then you will many times have encountered nights when it is bright enough without a moon to safely walk through the bush without a torch even if it is not bright enough to read a newspaper with as it is on some full moon nights. People have puzzled about this for centuries.
Unfortunately because of artificial lighting most people will have never seen this phenomenon. Most indeed have never seen ‘the glory of the everlasting stars’ as Clancy of the Overflow did – or even the Milky Way. My wife Della did not even know you could see the Milky Way with the naked eye (Yes, the largest thing in the night sky!) until I took her camping when we were first courting when she was 18 – and she was astonished (and hooked!) She was a city girl back then and I was doing my (short) stint of living in the city (less than 5 years of my life) it seems now expressly for the purpose of meeting her (the best bit – the degrees have never been much use). Since then we have mostly lived our lives out of sight of the nearest house.
One of the first times I noticed it (though I must have seen it many times before) was when I was camping out (alone) miles from anywhere after a long walk on the top of the Watagan Mountains near Newcastle at age 13-14. I was at first delighted then concerned when all about me became clearly visible. I thought at first it was search lights from the Flying Boat Base at Rathmines many miles away, but I would have been able to see their beams snaking across the sky. Then I thought it was the beginning of moonrise but it never appeared. Even wilder thoughts raced through my head (flying saucers and such) but I suffered no abduction, so I just lay back and enjoyed the light show.
I have encountered it many times since then. Now there is an explanation which you can find here and here. ‘The Romans referred to it as the “nocturnal sun”. Later accounts describe it as an unexplained glow – bright enough to read a book by – that would sometimes light up the night sky…Using satellite data, two atmospheric scientists from the Toronto institution suggest that the bright nights are not due to the sun or meteors, but instead the result of converging “zonal waves” in Earth’s upper atmosphere…finding that wavelengths in the upper atmosphere were at times superimposed over each other, brightening the airglow by as much as tenfold.
Their analysis showed these bright nights occurred 7% of the time and were highly localised, confined to an area about the size of Europe. But outside of remote areas, chances of seeing an event nowadays are slim, due to widespread light pollution.’