A white streak in the sky marks the movement of a police helicopter during a 2.5 seconds exposure.
Move cursor over the image to see a close up of the trace, revealing the helicopter's search light (white line), red anti-collision light (red line) and flashing lights (dots).
Photo taken in Antwerp, Belgium, on January 30, 2008. The spherical glow on the horizon is caused by a combustion flame of a petrochemical complex northwest of the city.
[© Wim VAN UTRECHT/CAELESTIA]