Square Kilometre Array, Radio telescope array in South Africa and Western Australia

The Square Kilometre Array is a radio telescope project with two arrays: SKA-Mid in South Africa's Karoo, near Carnarvon, and SKA-Low at the Murchison Radio-astronomy Observatory in Western Australia. SKA-Mid uses 197 parabolic dishes 15 m across, seen as white reflectors on pale supports across reddish-brown ground; SKA-Low uses 131,072 broadband antennas 2 m tall. Construction began on 5 December 2022.

Construction at this research site started in December 2022, after decades of preparation through international cooperation. Earlier, test facilities were built to trial the technology under real conditions.

The name refers to the notional collecting area of about one square kilometre, not to the array's physical extent, which reaches receiving stations up to 3,000 km from the core. The SKAO consortium was founded in Rome in March 2019 by seven countries: Australia, China, Italy, the Netherlands, Portugal, South Africa and the United Kingdom. Its headquarters are at Jodrell Bank Observatory in Cheshire, England.

The SKA-Mid dishes rise on the dry, reddish-brown ground of the Karoo near Carnarvon in South Africa's Northern Cape, while the low-frequency antennas are in Western Australia's Murchison region. The sites sit in radio-quiet zones: Australia's was established on 11 April 2005 to protect the Murchison Radio-astronomy Observatory. Access is restricted, and electronic devices can interfere with the receivers.

The array captures radio waves with wavelengths of a few centimeters (about an inch), which pass through cosmic dust and thus make invisible processes visible. This technique allows researchers to study objects that remain hidden in visible light.