Opening Up the Southern Heavens

By accidents of nature and wealth, many of the most interesting stellar objects are inaccessible to the earth's most powerful optical telescopes. The objects are visible only from the Southern Hemisphere; the biggest telescopes, such as the massive 200-inch instrument atop California's Mount Palomar, are located in the Northern Hemisphere.

The resulting gap in astronomical research will soon be filled by ten U.S. universities, the European Southern Observatory agency and a joint British-Australian group, which have started building three 146-to 150-inch telescopes in southern latitudes this year. A U.S. telescope costing about $10 million will rise at Cerro Tololo in the Chilean Andes, 300 miles north of Santiago. A European instrument will be placed on nearby La Silla Mountain. In Australia, a $12.3 million instrument is slated for Siding Spring Mountain, 200 miles from Sydney.

"The fundamental problems of modern astronomy are connected with the origin and evolution of stars and galaxies," says Olin Eggen, director of Australia's Mount Stromlo Observatory. "We have come to some general ideas on how stars are formed, evolve and decay, and on the dynamics of our galaxy. But the subject still abounds in unsolved problems."

Studying the Milky Way. Foremost among the problem regions to be studied under optimum conditions for the first time is the center of the earth's own galaxy. That portion of the Milky Way is only partially visible in the Northern Hemisphere for a few hours each night, and then only during summer months. In the Southern Hemisphere, the center of the galaxy moves directly overhead six months of the year. Moreover, the closest galaxies to the Milky Way--the Large and Small Magellenic Clouds, more than 160,000 light-years away, can be seen only from the Southern Hemisphere.

From there, says Dr. Nicholas Mayall, director of Arizona's Kitt Peak National Observatory, "we will be able to study star systems in a different state of evolution from our own." In addition, such observations will clarify man's understanding of universal distances, and provide optical studies of many radio sources for the first time. "By studying the Southern Hemisphere," says Mayall, "we will find if the distribution of radio objects, such as quasars, is even, uneven, clustered or what. If the observations show that quasars are not uniform but are instead clustered around the north and south galactic poles, we will have a clue that they may be related to our own galaxy."

Big Step. Study of the southern heavens will provide checkpoints on what scientists have learned in the past several years about X-ray sources in space. It will also yield some of the secrets of spectacular globular star clusters like Omega Centauri, 15,000 light-years from earth. The brightest clusters, including those nearest the earth, can be found only in the southern sky. Since the clusters are believed to contain some of the oldest stars in the Milky Way, they may provide invaluable knowledge regarding the age of the universe.

"In this business," says Mayall, "the unexpected is a way of life. And exploration of the Southern Hemisphere skies by large optical telescopes will likely be as big a step toward the discovery of new unexpecteds as astronomy has taken for a long, long while."

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