A star trail is a type of photograph that uses long exposure times to capture diurnal circles, the apparent motion of stars in the night sky due to Earth's rotation.

The stars seem so fixed that ancient sky-gazers mentally connected the stars into figures (constellations) that we can still make out today. But in reality, the stars are constantly moving. They are just so far away that the naked eye cannot detect their movement.

Have your aperture set to the widest, ISO around 320 to 640, and shutter speed 20 seconds. Manually focus on a bright star in the sky (do this by zooming in on live view). Take a test shot and review your image.

Description: A star trail is a long exposure photograph that shows the movement of stars in the night sky. The stars appear to move in the sky but it is actually the rotation of the Earth that causes the perceived movement.

Star trails reflect Earth's rotation, or spin, around its axis. The Earth makes a complete rotation relative to the backdrop stars in a period of about 23 hours and 56 minutes.

The reason star trails are circular is is caused by the rotation of the Earth. For any given exposure time these trails appear longer and less curved nearer the celestial equator, while nearer the celestial pole the paths are shorter and more strongly curved.

This motion is due to the Earth's rotation from west to east, which causes celestial bodies to have an apparent motion from east to west. A long-exposure photograph of the night sky shows the diurnal motion as star trails – circular orbits (or arcs) centred on the north and south celestial poles.