SALT marks 20 years of astronomical achievements

The Deputy Minister of Science, Technology and Innovation Nomalungelo Gina, along with prominent astronomers and international partners, will celebrate the 20th anniversary of the largest telescope in the southern hemisphere on November 10.

National Research Foundation board chairperson Professor Mosa Moshabela will deliver the keynote address. 

The Southern African Large Telescope (SALT), nicknamed Africa’s Giant Eye on the Sky, which was constructed during the 1990s at the South African Astronomical Observatory (NRF-SAAO) site in Sutherland, Northern Cape, is one of the largest telescopes in the world. 

The South African government committed US$10 million toward the project that was completed in 2005. 

The 11-metre optical telescope can magnify distant objects in the universe, a billion times too faint to be seen with the unaided eye.

The programme will showcase SALT’s scientific achievements, global partnerships, and contributions to the advancement of astronomy on the African continent, including: 

• Kilonova of GW170817 (2017): SALT took part in the first multi-messenger event. It was among the first telescopes to observe the optical afterglow of the first detected neutron star merger, obtaining a crucial, early spectrum of the kilonova associated with the gravitational wave event GW170817. These data helped confirm heavy element synthesis models in the merger ejecta—a landmark in multi-messenger astronomy.
• Exoplanet Microlensing (2019): SALT played a crucial role in a campaign that used gravitational microlensing to discover new exoplanets. 
• Eight Super-Hot Stars Unveiled (2020): Using SALT, astronomers identified eight new extremely hot sub dwarf stars—rare helium-burning stars with surface temperatures over 100,000 ° K. These discoveries provided insight into late stages of stellar evolution, with SALT’s UV-sensitive spectroscopy proving crucial in the analysis of their atmospheres.
• “Peekaboo” Galaxy Discovery (2022): SALT helped to characterise a tiny nearby galaxy nicknamed the “Peekaboo Galaxy”, which had only recently emerged from behind a fast-moving star. SALT spectra showed the galaxy has extremely low metallicity, akin to galaxies in the early Universe. This finding, combining SALT and Hubble Space Telescope data, offers a unique local window into primordial galaxy conditions.
• Four-Star Multi-Stellar System (2023): SALT, in partnership with the University of Canterbury’s observatory, discovered an unusual quadruple star system with two pairs of closely orbiting stars. SALT’s spectra confirmed the gravitational binding of the four stars, providing a testbed for theories of multi-star formation.