The Gran Sasso and the future of the giant of the South

From Gran Sasso to Mars the way is short. Vincenzo Cerulli travelled it with his eye. On 2 October 1910, from the Collurania astronomical observatory, a hill just outside Teramo from which you can see the Gran Sasso with your eyes, he discovered an asteroid christened Interamnia, the name of Teramo in Latin and, in memory of his studies on Mars, the Cerulli crater on the Red Planet is dedicated to the Abruzzese astronomer. After graduating in physics in Rome and studying in Berlin, the researcher, in his early thirties, bought a hill near Teramo, to which he gave the name Collurania (Hill of the Sky), and set up an astronomical observatory with modern instruments for the time. It was the beginning of a story of discoveries that Stefano Ardito retraces in his great act of love dedicated to Gran Sasso. The Giant of the South. Slopes, mountaineers, journeys, woodcutters, shepherds: that of the Gran Sasso, writes Ardito, "is a little-known and fascinating story, made up of desires and hopes, victories, dramas and in some cases death. A story that sometimes reads like an adventure novel, sometimes forces those who tell it to draw up lists that risk being boring. A story that includes exploits of absolute level and adventurous but easier ascents. A story in which, as in all stories, it is necessary to make distinctions and comparisons'.

Among the lesser-known stories is certainly that of the birth of the astronomical observatory. Cerulli had it built at his own expense around 1890-1891, only to hand it over to the State in 1917, burdened with a thousand commitments. But up there, in the clear air of Campo Imperatore, the study of the stars still found a home: Giuseppe Armellini, the astronomer who directed the Roman Observatory of Monte Mario, thought of "a branch, located at great height", to be used "for the most delicate work of modern sidereal astronomy". He worked hard, but the war hindered the arrival in Abruzzo of the telescope built by Zeiss and promised by Hitler to Mussolini. Stargazing can wait in the face of pain, hunger and despair. In 1945, the project became a reality thanks to Duke Vincenzo Rivera, who owned vast lands on the Gran Sasso. The politician had good connections in the DC and convinced US Marshall Plan officials to send part of the 14 billion dollars allocated by the Washington government for Italy to Abruzzo. Thus, in 1948, the Campo Imperatore Observatory was born. Everything went slowly but the telescope, a Schmidt model, built by the American company Penn Optical for the optical components and by the Italian company Marchiori for the mechanical structure, was completed in 1958. The scientific life of the Gran Sasso began with the study of supernovae, star formation, X-ray and gamma-ray emissions and the infrared photometry of galaxies. And in 2017, the Teramo Observatory and the Campo Imperatore Observatory were united in a new structure: the Inaf-Osservatorio Astronomico d'Abruzzo was born.

The giant of the South is nature and science at the same time: it is the destination of scholars from all over the world who work at the Gran Sasso Laboratories, consisting of three halls, carved into the rock and of colossal dimensions. Each one measures 100 metres long, 18 metres wide and 18 metres high. Including the tunnels and other service rooms, the total volume is 180,000 cubic metres. The extraordinary environmental conditions make the Laboratories the perfect environment for studying the physics of neutrinos produced in the Sun and in supernova explosions, for searching for dark matter particles and for studying nuclear reactions of astrophysical interest. Thus, the mountain, conquered by Francesco De Marchi, the Bolognese engineer who climbed the Corno Grande in 1573, is projected into the future.

The forests, the slopes, the climbs, the mountaineers who have sought glory on its walls, the 2009 and 2016 earthquakes that undermined its certainties are history, but the greatness of the giant of the South is its thirst for tomorrow. At the end of the winter of 2022, glaciologist Jacopo Gabrieli and colleagues measured the Calderone glacier and discovered that the maximum thickness of the ice was 26 metres. A few months later, the scholars, searching for the effects ofclimate change, extract a 45-quintal 'carrot' that is cut into one-metre segments and taken to Venice to be stored at 25 degrees below zero. Ardito is passionate about this new destiny of the Gran Sasso and tells how in the future, part of this 'white treasure', together with ice from the Alps, Kilimanjaro and the Himalayas, will be transferred to Antarctica, to the French-Italian base of Concordia, at an altitude of more than 3,000 metres. The ancient soul of the Gran Sasso thirsts for the future.

Stefano Ardito, Gran Sasso. Il gigante del Sud, Solferino Libri, pp. 352, euro 20.50