Exxtra: star trails

Have you ever wondered how many stars there are in the sky? And, is the light of all the stars the same color? A modern camera lens and a sensor see more than the human eye can. In fact, when doing long exposure photography, they also register movement that might normally be invisible.

It is virtually impossible to record star trails near cities, so first I had to find a suitable place. The light pollution map helped me with that. After all, for astronomers the light of cities and villages is a pollution. The car journey to the area freed from the light took me two hours: not only did I come across a very thick fog on the way, but also in the last part of the journey I had to fight an icy road on the slope of the mountain. Yes, I had to get to te mountain top to be above the fog, and by the way away from other cars' lights. Anyway, finally I got there and started photographing from the tripod. After a few test photos that allowed me to understand how to set up the camera, I took the photo that I expected to be the good one. But when I took the camera in my hands to review the picture, it turned out that during the exposure I must have hooked the tripod accidentaly, because all traces of the stars were equally broken! Clearly it was worth checking the photo taken, otherwise I would be back home with nothing. To repeat the shot I stayed for another 20 minutes in the cold. This time, however, I promised myself not to approach the tripod.

Ultimately, including the travel time it took me 6 hours to take this photo. I was back at home at 4 am. So the night was very late, but now the satisfaction is considerable. Looking at the traces of the stars, it is hard to believe that in the 20 minutes long exposure time the Earth rotated that much, and that it resulted in such a significant apparent movement of the stars. Another curiosity is an object with a brightness similar to that of a star, saved in the lower right part of the photo, right above the trees. The object that has changed the direction!