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The Light of Two Centuries: Giant Eyes of the Cape
One hundred years ago, the McClean telescope marked the beginning of
astrophysics in Southern Africa. By 2005 the giant SALT telescope will take
astronomy in the Southern hemisphere to new heights.
The Old: First Fingerprints of the Stars
The McClean telescope, the largest in the southern hemisphere when it was
new, is officially 100 years old. The telescope that marked the real
beginning of astrophysics in South Africa was dedicated 100 years ago,
starting South African astronomy off on a new footing as the new century
began. With this telescope, astronomers at the Cape began analysing
starlight in detail, making the first detections of two chemical elements
(silicon and europium) in stars, and measuring the motions of stars in three
dimensions. Today it is through this telescope that visitors to SAAO
typically see the stars and planets --- but its 60-cm main lens is dwarfed
by the 1.9-m mirror of the largest telescope at Sutherland, and still more
by telescopes in Chile and Hawaii with mirrors 8-10 metres across.
The New: A Tale of Two Towers
The Southern African Large Telescope (SALT), now rising from a Karoo koppie as a symbol of the new South Africa's commitment to science and progress,
has passed its first anniversary since groundbreaking. Like its predecessor it will take South African scientists into realms they could only dream
about before, starting the new century by again giving them access to the largest telescope in the southern hemisphere. By some measures, it may be
the largest in the world. Groundbreaking last year has been followed by rapid construction. The major contracts have been awarded, with about 60%
going to South African companies (by value), and overseas contractors
committed where possible to working with local firms as suppliers. The
foundations and pilings are in place, and two towers (dome and optical
alignment tower) stand on the observing plateau, not far from the existing
telescopes of the South African Astronomical Observatory. Date of full
operation: 2005.
Waiting for 2005
Like the McClean telescope, the new giant (with an effective maximum
diameter of nearly 10 metres) will be designed for decoding starlight
(breaking up the light of distant stars and galaxies into its component
colours for detailed analysis). With a light-collecting area 274 times
greater than the McClean, and modern electronic detectors, SALT will be able to detect distant galaxies whose light is no brighter than a candle flame on
the Moon, galaxies so distant that their light started toward us when the
Universe itself was new. In closer galaxies, where the light that reaches us
is only as old as humanity, SALT will let us study the nature of distant
suns, in regions where conditions are by no means the same as in our own
neighbourhood. Around stars where the light that reaches us started out
only hundreds or thousands of years ago, SALT can search for planets around suns too distant for lesser telescopes. Here on Earth, in South Africa, SALT
will gather light on its hill, a constant reminder of the ancient connection between earth, sky and the human mind, in one of mankind's most ancient
homes.
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