Jewels in the Southern Skies—Viewed from Chile
By “Awake!” correspondent in Chile
THE long, narrow land of Chile is one of many extremes. In the south, where water-laden clouds drop a yearly rainfall of a hundred inches, there are weeks on end that pass without seeing the sun. Far to the north are vast dry reaches of desert where only about five inches of rain have fallen in the last five years. Here in this in-between area, about 250 miles north of Santiago, lies the “Norte Chico” (Little North) and the city of La Serena, an international center for astronomy.
Why has this sparcely inhabited, near desertlike region bordered by the Pacific Ocean and the towering Andes mountains awakened so much astronomical interest in the last ten years? Because three new observatories have been built in this area, with telescopes ranging from ten to sixty inches. The desire is to have major astronomical instruments in the southern hemisphere to study celestial objects that cannot be readily observed from the northern hemisphere.
For example, there are the Magellanic Clouds, various southern hemisphere galaxies and some of the brightest star clouds. Myriads of stellar jewels shine in the Southern skies!
So a search was made for a suitable location in the southern hemisphere, and the final decision was made in favor of the “Norte Chico.” Why?
According to astronomer Dr. J. A. Graham, this area has the clearest and darkest skies enjoyed by any ground-based observatory. In fact, the nearby Elqui valley is known as the “tierra del eterno cielo azul” (land of the eternal blue sky).
Also, this section is distant from any large cities that could cause negative observing factors, such as smog and flashing neon lights. In this dry region there is an almost complete absence of atmospheric turbulence that normally causes the “twinkling” of the stars. These factors contribute to making this region a corridor of observatories.
According to Dr. V. M. Blanco, director of the Cerro Tololo Inter-American Observatory, “under such fine observing conditions, the telescopes at Cerro Tololo are far more effective than instruments of similar size at Northern Hemisphere sites found so far.” Another astronomer said: “With the 60-inch reflector, we can carry out certain extragalactic studies which in the northern hemisphere would require a 600-inch telescope.”
A Visit to the Observatories
Recently arrangements were made to visit two of the observatories, the Cerro Tololo Inter-American Observatory, sponsored by a group of North American universities, and the European Southern Observatory, sponsored by six nations. The first objects that attracted our eyes were the telescope domes situated high atop a 7,100-foot-high peak. Arriving at the summit, we found ourselves surrounded by deep ravines that drop almost vertically some 1,900 feet.
On our tours we were asked if we had ever tried to count the glimmering stars shining above. We were told that the human eye can see about 5,000 stars, but only about 2,000 at any one time.
Thus the role of the telescope was made evident, for there are millions upon millions of stars in the universe. Why, in our galaxy alone, the Milky Way, there are thought to be about 100,000 million stars, and our galaxy is but one of thousands of millions of galaxies! The thought of so staggering a number of jewels in the skies brought to mind the scripture that invites us to think upon their Creator, Jehovah God: “Raise your eyes high up and see. Who has created these things? It is the One who is bringing forth the army of them even by number, all of whom he calls even by name.”—Isa. 40:26.
We stepped inside the telescope building and entered an elevator that took us up to the telescopes. Our guide showed us a large sixty-inch mirror that serves as an “eye” for the astronomer. Such a telescope might be compared to an enormous camera, and with its photographic plates and photoelectric detectors it can “see” much farther than the human eye. To illustrate, the forty-inch Schmidt telescope located on the site of the European Southern Observatory can observe objects one million times as far as the human eye can see.
How can astronomers tell the nature of stars? By means of radiation, which may be in the form of X rays, radio waves, infrared radiation or simply visible light. Thus, astronomers use these “cameras” to study the visible light of the celestial objects. Of the sixteen telescopes in operation at the three observatories, the majority are used mainly for studies of light by means of spectrography and photometry.
Our tour guide, astronomer Dr. Mart de Groot, explained that, basically, the spectrography separates the various colors of a beam of light as does a glass prism and represents them by lines on a photographic plate. An analysis of this plate will reveal the chemical composition of the atmosphere around the object, since each chemical element produces its own unique spectrum. For example, if a star has an atmosphere with a great deal of neon in it, the neon will absorb any yellow light emitted by the star. This will be revealed on the photographic plate, for the spot for yellow will show itself dark.
Photometry measures the intensity or quantity of light received by means of different colored filters. This system can be used to determine the temperature, brightness and distance of the object being studied.
It is evident, then, that the telescope does the seeing and recording and the astronomer does the analyzing. One astronomer told us that the organizing and analysis time may be more than four times as much as the actual observing time with the telescope. His analysis time may involve a comparison of his photographs with others of the same celestial region taken years or decades ago, thus revealing the relative movement of the stars, changes in brilliance, and the appearance of new stars.
These mirrors that can “see” so far are extremely sensitive to light. One of the observatories here was awaiting the delivery of a 101-inch mirror, which will be eighteen months in the process of grinding and polishing. This mirror has specifications that call for an overall surface configuration accurate to one two-millionths of an inch.
As we moved from one dome to another we could appreciate that much forethought must have gone into the planning of these structures so that maximum telescopic efficiency would be obtained. This is particularly true in Chile, since it belongs to a belt of seismic activities surrounding the Pacific Ocean. The frequent tremors require a design that will resist such movements to the greatest extent possible.
As we approached the large “home” for the 158-inch telescope at Cerro Tololo we felt like ants. The telescope and its moving parts weigh 300 tons, and its “home” measures 130 feet high, 108 feet in diameter, and weighs about 500 tons!
According to Dr. Bengt Westerlund, the study of the Large and Small Magellanic Clouds will be a major activity of the European Southern Observatory. These two galaxies are the nearest neighbors of our own Milky Way and present a marvelous picture to the viewer, appearing as two small clouds in the sky. These southern objects became known as the Magellanic Clouds, being named after the Portuguese explorer, Ferdinand Magellan. In 1520 he sailed through the passage at the tip of South America now known by his name. These galaxies, our “nearest” neighbors, are not exactly in our backyard. These Clouds are 50,000 parsecs away (a parsec equals 3.26 light years or 19,200,000,000,000 miles). So the Clouds are 960,000,000,000,000,000 miles away!
The astronomer would like to know what the stars are composed of, how they form, how long they shine, and when the universe came into existence. Thus the search into the vast expanse continues. With the addition of several large “eyes” in “la calle de los observatorios” (the street of the observatories), el Norte Chico de Chile is fast becoming one of the most important astronomical centers of the world.
Our tour ended. As we slowly wound our way down from the 8,000-foot peak at La Silla, the sun disappeared behind other hills that stretch off into the distance, leaving above us a blanket of deep black velvet sprinkled with glimmering diamonds—jewels in the Southern skies.