After several years of planning and no shortage of financial anxiety, construction has officially started on the Extremely Large Telescope. Contractors are now building the main structure and dome of the Chile-based observer ahead of its initial service in 2024. That's a long time to wait, but this is no mean feat. With a 43-yard aperture, this promises to be the world's largest optical telescope for sometime, even compared to future or in-limbo projects like the Thirty Meter Telescope. Those gigantic dimensions will help it capture far more light, giving astronomers the chance to spot particularly distant galaxies, find small planets and capture more details of larger planets.