Observatories of the World
ATLAS OF THE UNIVERSE
I
t is the Earth’s atmosphere which is the main enemy of
the astronomer. Not only is it dirty and unsteady, but it
also blocks out some of the most important radiations
coming from space. This is why most modern observ-
atories are sited at high altitude, often on the tops of
mountains, where the air is thin and dry.
Of course, this is not always possible. For example
there are no high peaks in Australia, and the observatory
at Siding Spring, near Coonabarabran in New South
Wales, lies at an altitude of less than 1150 metres
(3800 feet), though this does at least mean that it is easily
accessible (provided that one avoids driving into the kan-
garoos which roam the Warrumbungle range; the animals
have absolutely no road sense!). Another modern hazard is
light pollution, which is increasing all the time. The
Hooker reflector at Mount Wilson in California was actu-
ally mothballed for some years during the 1980s because
of the lights of Los Angeles, and even the great Palomar
reflector, also in California, is threatened to some extent.
Another indifferent site is Mount Pastukhov, where the
Russians have erected a 6-metre (236-inch) reflector. The
altitude is just over 2000 metres (6600 feet) but conditions Observatory sites.There
are major observatories
in all inhabited continents.
The modern tendency
is to establish large new
observatories in the southern
hemisphere, partly because
of the clearer skies and partly
because some of the most
significant objects lie in the
far south of the sky.▼ Dome of the William
Herschel telescope at La
Palma. It has a 4.2-m
(165-inch) mirror. It is sited
on the summit of Los
Muchachos, an extinct
volcano in the Canary
Islands, at an altitude of
2332 m (7648 feet). The Isaac
Newton Telescope is also on
Los Muchachos; it has a
256-cm (101-inch) mirror,
and was transferred to La
Palma in 1983.▼Domes on Mauna Kea.
Mauna Kea, in Hawaii, is an
extinct volcano over 4000 m
(14,000 feet) high. On its
summit several large
telescopes have been erected.
One of the most recent,
Gemini North, is seen in the
foreground. The mainadvantage of the site is the
thinness of the atmosphere,
and the fact that most of the
atmospheric water vapour lies
below. The main disadvantage
is that one’s lungs take in less
than 39 per cent of the normal
amount of oxygen, and care
must be taken.B Atl of Univ Phil'03stp 31/3/03 3:55 pm Page 16