Stars trails over Armazones

Multiple-exposure picture taken from the top of the 3046-metre-high Cerro Armazones, the selected site for the Extremely Large Telescope (ELT). Because of the rotation of the Earth, the night sky is seen as it rotates around the southern celestial pole. As a result of this movement, the stars describe dotted trails when a series of exposures is combined. The south celestial pole is visible near the centre of the image. On the right is the Differential Image Motion Monitor (DIMM), used to measure the atmospheric seeing. The white and red tower on the left of the DIMM is the meteorological station.