Dance of the cranes

A watched pot never boils, but luckily that doesn’t apply to us watching ESO’s Extremely Large Telescope (ELT) being constructed. This Picture of the Week shows a timelapse overlooking Cerro Armazones in the Chilean Atacama Desert over the course of 2023, as the dome of the ELT is pieced together in smooth choreography.

Partly built at a nearby base camp, large steel elements arrive at the peak ready to be neatly assembled together into the dome. The steel structure provides the skeleton around which a protective insulated cladding is now being applied. It rests on a concrete foundation separated from the central pier where the telescope will be, to reduce vibrations propagating through the ground. The dome can rotate on 36 trolleys, allowing the telescope to observe the whole sky.

A new webcam inside the dome shows progress in the azimuth structure that will support the telescope, as well as the two huge platforms that will hold the ELT’s scientific instruments.

In this timelapse, each frame was captured at the same time every day; the Sun’s apparent position in the sky changes with seasons as the Earth orbits around the Sun. This webcam view provides an incredible peek at the ELT construction progress, and we cannot wait to see the wonders its 39-metre eye will discover.