The construction of the dome for the world’s largest visible- and infrared-light telescope, the Extremely Large Telescope (ELT), has progressed significantly. Located atop Cerro Armazones in Chile’s Atacama Desert, this state-of-the-art observatory is being developed under the guidance of the European Southern Observatory (ESO). With its completion targeted for 2028, the telescope is anticipated to provide unprecedented insights into terrestrial exoplanets and the expansion of the universe. Currently, the telescope’s dome frame has been completed, with the outer shell still under construction.

Dome and Outer Shell Construction

According to a report by Space.com, the dome spans a diameter of 305 feet and stands 263 feet tall, making it comparable in size to a football field. Aluminum plates will be installed to shield the telescope from the region’s extreme weather conditions, which include fluctuating temperatures. Large sliding doors in the dome will allow the telescope to operate at night while remaining securely enclosed during the day.

Telescope’s Primary and Secondary Mirrors

The polygonal base inside the dome, which will house the telescope’s main mirror (M1), is nearing completion. The main mirror, expected to be the largest ever built for an optical telescope, will consist of 798 hexagonal glass ceramic segments. Each segment measures about 5 feet across and 2 inches thick. The secondary mirror (M2), with a diameter of 14 feet, is planned for completion later this year. Both mirrors will be supported by a central structure known as the “spider,” which is distinguished by its six arching arms.

Sophisticated Design for Precision Observations

The altitude structure of the telescope, standing 164 feet tall, is designed to support all five mirrors while rotating to observe different parts of the sky. Once fully operational, the ELT is expected to redefine astronomical research by delivering unparalleled observations of celestial phenomena, aiding researchers in unlocking the mysteries of the universe.