English: ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special “Then and Now” comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

Here are two photographs of La Silla, taken in June 1968 and the present day from near the observatory’s water tanks, looking over the rest of the site. You can examine the changes with our mouseover image comparison.

In the historical image, the provisional residential area is visible in the foreground. The three telescopes in the background are, from left to right, the Grand Prism Objectif (GPO, first light in 1968), the ESO 1-metre telescope (first light in 1966), and the ESO 1.5-metre telescope (first light in 1968). These three telescopes were the first at La Silla. The white dome closest to the viewer is the ESO 1-metre Schmidt telescope, which began work in 1971.

Today, these four domes are still present, but the first three telescopes have been decommissioned. The ESO 1-metre Schmidt is still in operation, but is now a project telescope dedicated to the LaSilla–QUEST Variability survey (see potw1201a).

The present-day photograph also shows two new telescopes. The silver dome is that of the MPG/ESO 2.2-metre telescope, which has been in operation since early 1984 and is on indefinite loan to ESO from the Max-Planck-Gesellschaft. On the far left is the Danish 1.54-metre telescope, in use since 1979, which is one of several national telescopes at La Silla.