God the speed freak
With Planet Earth spinning on its axis at roughly 1000mph (1600kph) its amazing how we dont ever feel the spin. To get evidence of this, there is a couple of ways we can use modern digital slr camera's mounted a sturdy tripod to capture this phenomenon.
The first way is to tell the camera to take one long exposure picture over an extensive period of time i.e. 1hr plus. The upsides to this is, one picture to edit, good results with smooth trails and its easier to set up... though there is a few downsides as well. 1 is burning out the camera sensor as it will get hot the longer its in use, 2, unwanted ambient light such as, city glow that could wash out some of the stars, and 3 the camera battery running out power.
The second way, which is my preferred method, is to tell the camera to take several shorter long exposure pictures of about 20-30secs, over long period of time, and blend them all together in post processing. An intervolometer is required this way to control the camera. The upsides for this method is, 1 having more control over what goes in and stays out the final picture. i.e. if there's any anomalies in any of the single pictures can be removed. 2 less worry about the battery running out and ruining the final picture and three still achieve great results. The downsides, Gaps in the star trails can appear due to the camera saving the previous picture and starting the next picture and two, is running out of memory space on your memory card from taking 100's of photos and changing cards will create a gap in the trails.
These two images were created using the second method. The first image with the windmill was taken over a period of about 1.5hrs and consists of 106 images, each image was 50sec long. Also a torch used on one of the images to light up the foreground and windmill.
The second image was taken over a period of about 2hrs and consists of 300 images, each image was 20sec long.