Its primary mirror is made up of 91 hexagonal segments spanning about 11 by 10 metres, and it was built for roughly a fifth of the cost of a conventional telescope of similar power by using an innovative fixed-angle design. Opened in 2005 by then-President Thabo Mbeki, SALT has contributed to discoveries ranging from exoplanets to the behaviour of black holes, and it sits at one of the darkest, clearest night-sky sites on Earth.
Source: South African Astronomical Observatory (SAAO)
Frequently Asked Questions
How did South Africa come to build one of the world's biggest telescopes?
Following a national science strategy in the late 1990s, South Africa's democratic government funded the project starting in 1998, choosing Sutherland's high-altitude, low-light-pollution site and modelling SALT's design on a similar telescope in Texas to keep costs down.
Why is SALT's design considered innovative rather than just "big"?
Instead of a telescope that can point anywhere in the sky (which is expensive to engineer), SALT is fixed at one elevation angle and tracks objects using a moving instrument package, letting it achieve a huge mirror size at a fraction of the usual cost.
What has SALT contributed to astronomy in recent years?
It has been used to study gravitational-wave events, distant supernovae, and interacting binary star systems, and its dark-sky location continues to make it a sought-after facility for international research collaborations two decades after it opened.