Pale Blue Dot - Carl Sagan [67]
*Today many telescopic images are obtained with such electronic contrivances as charge-coupled devices and diode arrays, and processed by computer—all technologies unavailable to astronomers in 1970.
*James B. Pollack made important contributions to every area of planetary science. He was my first graduate student and a colleague ever since. He converted NASA’s Ames Research Center into a world leader in planetary research and the post-doctoral training of planetary scientists. His gentleness was as extraordinary as his scientific abilities. He died in 1994 at the height of his powers.
CHAPTER 12
THE GROUND MELTS
Midway between Thera and Therasia, fires broke forth from the sea and
continued for four days, so that the whole sea boiled and blazed, and the
fires cast up an island which was gradually elevated as though by levers …
After the cessation of the eruption, the Rhodians, at the time
of their maritime supremacy, were first to venture upon
the scene and to erect on the island a temple.
STRABO, GEOGRAPHY (CA. 7 B.C.)
All over the Earth, you can find a kind of mountain with one striking and unusual feature. Any child can recognize it: The top seems sheared or squared off. If you climb to the summit or fly over it, you discover that the mountain has a hole or crater at its peak. In some mountains of this sort, the craters are small; in others, they are almost as big as the mountain itself. Occasionally, the craters are filled with water. Sometimes they’re filled with a more amazing liquid: You tiptoe to the edge, and see vast, glowing lakes of yellow-red liquid and fountains of fire. These holes in the tops of mountains are called calderas, after the word “caldron,” and the mountains on which they sit are known, of course, as volcanos—after Vulcan, the Roman god of fire. There are perhaps 600 active volcanos discovered on Earth. Some, beneath the oceans, are yet to be found.
A typical volcanic mountain looks safe enough. Natural vegetation runs up its sides. Terraced fields decorate its flanks. Hamlets and shrines nestle at its base. And yet, without warning, after centuries of lassitude, the mountain may explode. Barrages of boulders, torrents of ash drop out of the sky. Rivers of molten rock come pouring down its sides. All over the Earth people imagined that an active volcano was an imprisoned giant or demon struggling to get out.
The eruptions of Mt. St. Helens and Mt. Pinatubo are recent reminders, but examples can be found throughout history. In 1902 a hot, glowing volcanic cloud swept down the slopes of Mt. Pelée and killed 35,000 people in the city of St. Pierre on the Caribbean island of Martinique. Massive mudflows from the eruption of the Nevado del Ruiz volcano in 1985 killed more than 25,000 Colombians. The eruption of Mt. Vesuvius in the first century buried in ash the hapless inhabitants of Pompeii and Herculaneum and killed the intrepid naturalist Pliny the Elder as he made his way up the side of the volcano, intent on arriving at a better understanding of its workings. (Pliny was hardly the last: Fifteen volcanologists have been killed in sundry volcanic eruptions between 1979 and 1993.) The Mediterranean island of Santorin (also called Thera) is in reality the only part above water of the rim of a volcano now inundated by the sea.* The explosion of the Santorin volcano in 1623 B.C. may, some historians think, have helped destroy the great Minoan civilization on the nearby island of Crete and changed the balance of power in early classical civilization. This disaster may be the origin of the Atlantis legend as related by Plato, in which a civilization was destroyed “in a single day and night of misfortune.” It must have been easy back then to think that a god was angry.
Volcanos have naturally been regarded with fear