ESO Open House Day 2011

The full-size replica of the ELT’s 39.3-metre mirror nears completion at ESO’s Open House Day 2011 in Garching bei München, with the ESO Headquarters in the background. The mock-up was made of 798 cardboard hexagons, each around 1.4 metres across. The ELT will be the largest optical/infrared telescope in the world.