> I keep trying to imagine what it's like to be there. Some of the pictures > look like a flash of light, some like the sky is filled. Is the light > constantly changing? Does the sky give enough light to see by, in comparison, for > example, to a full moon on a clear night? Are they there all the time when the sky > is clear? The light is constantly changing, dancing (hence the merry dancers). This particular display was an especially good one. There was easily enough light to see to move around, I just had to use a torch to see the settings on my camera. The photos I took were generally at a shutter speed of about 30 seconds, so there's a bit more on the image than you'd see with your eyes at the time. The longer time also intensifies the colour. They were all taken for similar times, so you can judge from that how much the light was changing - some times it was much brighter than others, the colours were constantly changing too. This display was spectacular in that it wasn't just to the north, it was the whole sky that was lit up at times. One of my photos was taken looking straight up, most of the others were actually looking east or west rather than north. Most of the time we just spent outside gazing up, marvelling. It really is awe-inspiring, we stood outside for the best part of 3 hours just watching (luckily it wasn't a windy night!). No, they're not there all the time (as far as I know - physics never was my strong point) - it's basically caused by high speed particles from the solar wind colliding with atmospheric gasses at high altitudes. When there's active sun spots the aurora is generally more active (depending on whether the solar flares are thrown out in the direction of the earth or not). There's been some incredibly powerful solar flares recently, and the ones at the end of Ocrober/start of November were amongst the strongest ever recorded. Just found a good bit of information about the northern lights: "On their way down towards the geomagnetic poles, the solar particles are stopped by Earth's atmosphere, which acts as an effective shield against these deadly particles. When the solar particles are stopped by the atmosphere, they collide with the atmospheric gases present, and the collision energy between the solar particle and the gas molecule is emitted as a photon - a light particle. And when you have many such collisions, you have an aurora - lights that may seem to move across the sky. In order for an observer to actually see the aurora with the naked eye, about a 100 million photons are required." This was by far the best display of the merry dancers that I've ever seen. Mostly when we've seen it, it's been greeny colours, with the off bit of purple. This was the first really coloured display that I've seen. Sometimes it's just silvery or greeny, and just looks like the moon lighting up clouds. Fiona Orkney