ELT's first rotation marks milestone for a 3,500-ton telescope

The European Southern Observatory’s Extremely Large Telescope rotated its 3,500-ton structure for the first time on its Chilean mountaintop, marking a major milestone in its assembly. Weighing about 7.7 million pounds now, the ELT will grow larger as mirrors and instruments are installed later, ultimately surpassing 10 million pounds and enabling unprecedented views of the night sky.