Earth’s rotation creates a problem for photographers who want to image the night sky. A time exposure results in stars that look like arcs, and any object larger than a point will appear blurred. Furthermore, most imagers don’t want to expend the effort needed to transport and set up a telescope’s drive system, which would correct the problem.
Instead, manufacturers have created small, easily portable devices that counteract Earth’s motion. (But note that if you include land in your image, your camera will record it as blurred.) I recently acquired two of these “sky trackers.” Each approaches the problem in a different way. One is a miniature equatorial mount, and the other utilizes a tangent arm assembly driven by a lead-screw.