First ELT main mirror segments successfully cast

The first hexagonal segments for the main mirror of ESO’s Extremely Large Telescope (ELT) are shown being successfully cast by the German company SCHOTT at their facility in Mainz. These segments will form parts of the ELT’s 39-metre main mirror, which will have 798 segments in total when completed. The ELT will be the largest optical telescope in the world when it sees first light.