People cause a lot of radio wave interference with their cell phones, radio and television broadcasts, air traffic, and many other radio devices. Therefore, radio telescopes must be built as far away as possible from big cities.
South Africa has a 26-m diameter radio telescope (that’s a huge dish!) at the Hartebeesthoek Radio Astronomy Observatory in a valley west of Krugersdorp. Hills around this site help to shield the radio telescope from radio signals from Tshwane and Johannesburg, for example from microwave ovens and cellphones.
South Africa is currently building the Karoo Array Telescope, or MeerKAT, a mid-frequency ‘pathfinder’ or demonstrator radio telescope, near Carnarvon in the Northern Cape. It will be the largest and most sensitive radio telescope in the southern hemisphere until the SKA is completed.
But, most exciting of all, the majority of the SKA – the full dish array and the dense aperture array – will be built in Africa. The core – i.e. the region with the highest concentration of receivers – will be constructed in the Northern Cape Province, about 80 km from the town of Carnarvon (the same site as where the MeerKAT is being constructed).