Qualla: Southern African Large Telescope

Southern African Large Telescope: Introduction

Mon, 09 Mar 2026 00:00:00 GMT

Photo credit Public domain. Ninety-one hexagonal mirrors, each one metre across, fitted together like a honeycomb on a remote hilltop in the Karoo semi-desert. Together they form the Southern African Large Telescope, or SALT, the largest optical telescope in the Southern Hemisphere. The instrument sits 1,837 metres above sea level near the small town of Sutherland, 370 kilometres northeast of Cape Town, in a landscape chosen precisely because almost nothing happens there: no city lights, minimal atmospheric disturbance, and skies so dark that the Milky Way casts shadows on the ground.

Image: Public domain

Southern African Large Telescope: A Mirror Built from Pieces

Mon, 09 Mar 2026 00:00:00 GMT

Photo credit Carolina Ödman, CC BY-SA 2.0. SALT's primary mirror spans 11.1 by 9.8 metres, yet no single piece of glass could be made that large and that precise. Instead, the telescope uses an array of 91 identical hexagonal segments made from low-expansion Sitall glass, each adjustable in tip, tilt, and piston to align ...

Image: Carolina Ödman | CC BY-SA 2.0

Southern African Large Telescope: First Light Over the Karoo

Mon, 09 Mar 2026 00:00:00 GMT

Photo credit Roelof Valentine, Valroe at en.wikipedia, Public domain. Installation of the mirror segments began in March 2004, and the last hexagon was set in place in May 2005. First light came on 1 September 2005, when SALT captured 1-arc-second resolution images of the globular cluster 47 Tucanae, the open cluster NGC 6152, the spiral galaxy NGC...

Image: Roelof Valentine, Valroe at en.wikipedia | Public domain

Southern African Large Telescope: Hunting the Invisible

Mon, 09 Mar 2026 00:00:00 GMT

Photo credit Lengau, CC BY-SA 4.0. SALT was designed primarily for spectroscopy, the analysis of light broken into its component wavelengths, which reveals the composition, temperature, and motion of distant objects. It can observe stars and galaxies a billion times too faint for the human eye. Its instruments inc...

Image: Lengau | CC BY-SA 4.0

Southern African Large Telescope: Stargazing Changes a Town

Mon, 09 Mar 2026 00:00:00 GMT

Photo credit South African Tourism from South Africa, CC BY 2.0. Sutherland, population roughly 5,000, was a quiet Karoo town before SALT arrived. The telescope has drawn about 14,000 visitors annually, falling short of the 30,000 initially projected but still enough to create at least 300 jobs in a community with few other economic drivers. K...

Image: South African Tourism from South Africa | CC BY 2.0