1/3 The last mirror segment of ESO's Extremely Large Telescope has been cast! The ELT's main mirror will be 39-m wide –– too large to be made from a single piece. Instead, the mirror will consist of 798 hexagonal segments working together.

133 extra segments will be needed during normal operations, as we'll have to recoat 2 segments/day. Together with 18 spares, this makes a total of 949 segments, and the last one has now been cast.

➡️ https://www.eso.org/public/news/eso2410/

#astronomy #engineering

📷 SCHOTT