Star Trails

FEB 25, 2011

A few nights ago, I set my Canon digital SLR camera on a tripod and aimed it out my bedroom window pointing north toward Polaris, the North Star. I attached my computer to the camera and using software that came with the camera I set it to take 2 minute exposures one after another for about 3.5 hours---100 images in total. In the morning, I stacked the images to make the long-exposure image shown here. The stars appear to circle around the north celestial pole. Of course, the stars aren't moving---we are. As the Earth turns on its axis, completing one rotation per day, the fixed stars appear as if they are turning. The other streaks of light are aircraft coming and going from local NYC airports. It was a busy night.