Expedition 31 Flight Engineer Don Pettit relayed some information about photographic techniques used to achieve the images: βMy star trail images are made by taking a time exposure of about 10 to 15 minutes. However, with modern digital cameras, 30 seconds is about the longest exposure possible, due to electronic detector noise effectively snowing out the image. To achieve the longer exposures I do what many amateur astronomers do. I take multiple 30-second exposures, then βstackβ them using imaging software, thus producing the longer exposure.β
I fixed the camera up with the wide angle lens and took a few pictures of the stars, one of the stars around Orion and the other of the Big Dipper. I was looking in my Night Sky Mag. and found out that the star, Mizar, in the handle of the dipper is a binary star (with Alcor) and my picture even showed it. In reality it is a multiple star since if you magnified it enough you could see that it is a binary as well. Even funnier is that astronomers have discovered that each of these stars are binary as well but you cannot distinguish this in any telescope.
