Startrail

Startrail is a term used in astrophotography to describe a photograph that captures the apparent movement of stars across the night sky. This effect is achieved by using a long exposure time, typically ranging from several minutes to several hours. During this extended period, the Earth's rotation causes the stars to move from their initial position to a new one, leaving trails of light in the resulting image.

The appearance of startrails depends on several factors. The direction the camera is pointed significantly influences the pattern. If pointed towards the celestial poles, stars appear to rotate in circles around the pole star, such as Polaris in the Northern Hemisphere. If pointed towards the east or west, stars will appear to move in arcs. If pointed directly north or south, they will appear as curved lines. The duration of the exposure is also critical; longer exposures result in longer trails.

Achieving a good startrail photograph requires a stable camera mount, often a tripod, to prevent any camera movement other than that caused by the Earth's rotation. A camera with manual controls for exposure time and aperture is essential. The lens aperture is usually set to a mid-range value to ensure sharpness across the frame and manage exposure. Post-processing techniques, such as stacking multiple shorter exposures or adjusting contrast and color, are often employed to enhance the final image. Startrail photography is a popular technique for capturing the dynamic beauty of the night sky.