Asleep under the stars

The Swedish-ESO Submillimetre Telescope (SEST) sits under the night sky at its home, ESO’s La Silla Observatory. After seeing first light in 1987, it helped astronomers to study star formation and molecular clouds until it was decommissioned in 2003. SEST was among the earliest telescopes to see at large sub-millimetre wavelengths; it was the only such instrument in the Southern Hemisphere at the time of its first light. It is superseded by the instruments APEX and ALMA. The lines of light in the sky are star trails, created by multi-exposure photography as the stars appear to move in the sky over time, due to the Earth's rotation.