Here is more on the Extremely Large Telescope (ELT), currently under construction on Cerro Amazones in the Atacama Desert of Chile. With an aperture of 39.3 metres, the ELT will be the largest optical telescope in the world, and no larger telescope is currently planned. First light is planned for 2028. Cost is in the vicinity of € 1 billion, which is rather a bargain compared to the US$ 10 billion James Webb Space Telescope, which has an aperture of 6.5 metres.