Images like the one above are often taken by artistic astronomers and are called star trails. Stars, just like the sun and moon, rise and set every night due to the rotation of the Earth. These pictures show the path in which stars move across the sky over a single night. To image star trails, you either need to leave the shutter open on your camera all night and take one long picture, or take hundreds of images all night long and stack them together. Notice in the image above that many stars appear to rise above the horizon on the east and set on the west, but some move in a full circle and never rise or set. These stars are called circumpolar stars. Imagine you are standing at the tip of the North pole and looking up at the stars. All of the stars would appear circumpolar because you are standing on the tip of Earth's spin axis (also called the north celestial pole). Now if you move down to North America you'll be on the side of Earth's spin axis, and only some stars (those in the direction of the north celestial pole) will appear circumpolar. Similarly, if you are at the equator (middle of earth) there will be no circumpolar stars, because the north and south celestial poles sit exactly on the horizon. Based on images of these star trails you could measure the exact latitude of your location on Earth.
