If you mount your camera on a tripod and set your shutterspeed to more than 30 sec (bulb) and point your lens up to the sky you get this effect. It seem like the stars are moving.. surprise.. it is not. It is of course the rotation of our planet. I used shutterspeed 2837 sec on the first one and 1538 on the last one. That equals 47 minutes and 25 minutes. Be sure to have enough battery power :-)
For more skies around please visit SWF Homepage, feel free to join.