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For many centuries, maps of the southern sky showed extensive blank areas – the Terra
Incognita of the heavens.
1595. For the first time, Dutch traders set sail to the East Indies. At night, navigators
Pieter Keyser and Frederik de Houtman measured the positions of more than 130 stars in the
southern sky. Soon, celestial globes and maps showed twelve new constellations, none of
which had ever been seen before by any European.
The British were the first to construct a permanent astronomical outpost in the southern
hemisphere. The Royal Observatory at the Cape of Good Hope was founded in 1820. Not much
later, John Herschel built his own private observatory, close to South Africa’s famous
Table Mountain.
What a view! Dark skies. Bright clusters and star clouds high overhead. Little wonder that
Harvard, Yale and Leiden observatories followed suit with their own southern stations. But
the exploration of the southern sky still took lots of courage, passion and perseverance.
Until fifty years ago, almost all major telescopes were located north of the equator.
So why is the southern sky so important? First of all, because it was largely uncharted territory.
You just can’t see the whole sky from Europe. A prominent example is the centre of the Milky
Way, our home galaxy. It can hardly be seen from the northern hemisphere, but from the
south, it passes high overhead.
And then there are the Magellanic Clouds – two small companion galaxies to the Milky Way.
Invisible from the North, but very conspicuous if you’re south of the equator.
And then finally, European astronomers were hindered by light pollution and poor weather.
Going south would solve most of their problems.
A scenic boat trip in the Netherlands, June 1953. It was here, on the IJsselmeer, that
the German/American astronomer Walter Baade and the Dutch astronomer Jan Oort told colleagues
about their plan for a European observatory in the southern hemisphere.
Individually, no one European country could compete with the United States. But together,
they might. Seven months later, twelve astronomers from six countries gathered here, in the stately
Senate Room of Leiden University. They signed a statement, expressing the desire to establish
a European observatory in South Africa. This paved the way for the birth of ESO.
But hang on!… South Africa? Well, it made sense, of course. South Africa already had
the Cape Observatory, and, after 1909, the Transvaal Observatory in Johannesburg. Leiden
Observatory had its own southern station in Hartebeespoort.
In 1955, astronomers set up test equipment to find the best possible spot for a big telescope.
Zeekoegat in the Great Karoo. Or Tafelkopje, in Bloemfontein. But the weather was not all
that favourable.
Around 1960, the focus shifted to the rugged landscape of northern Chile. American astronomers
were also planning their own southern hemisphere observatory here. Harsh horseback expeditions
revealed much better conditions than in South Africa. In 1963, the die was cast. Chile it
would be. Six months later, Cerro La Silla was picked as the future site of the European
Southern Observatory.
ESO was no longer a distant dream. In the end, five European countries signed the ESO
Convention, on 5 October 1962 — the official birthday of the European Southern Observatory.
Belgium, Germany, France, the Netherlands and Sweden were firmly committed to jointly
reach for the southern stars. La Silla and its surroundings were bought from the Chilean
government.
A road was built in the middle of nowhere. ESO’s first telescope took shape, at a steel
company in Rotterdam. And in December 1966, the European Southern Observatory opened its
first eye on the sky. Europe had embarked on a grand voyage of cosmic discovery.
This is Dr J, signing off from this special episode of the ESOcast. Join me again next
time for another cosmic adventure.