ASTRONOMERS, physicists and even philosophers the world over are engaged these days in nothing less than a reappraisal of the origin and nature of the universe, largely because of the work of the man who appears on this week's cover. Dutch-born Professor Maarten Schmidt of California Institute of Technology is the astronomer who found the key to quasars (quasi-stellar radio sources), those bright, distant and mysterious objects that have been baffling astronomers. Now Schmidt and other scientists are using quasars to unlock some of nature's most difficult enigmas. Perhaps not since Galileo has an astronomer so jolted the specialists whose field of study is the universe.

The Schmidt story was not an easy one to report or to write. The world of quasar astronomy is one of nigh-incredible reaches in time, space and imagination. It involves unheard-of distances, temperatures and energy. It has its own logic and language, and it takes astronomy to the edge of theology, physics to the edge of metaphysics. It raises such questions as whether the universe came into being suddenly, or whether it existed forever--and in that case, what is "forever"? What is eternity? "The subject," says Science Writer Leon Jaroff, "makes the mind boggle, especially when you get into the area of cosmology, into the Einsteinian concept of space."

Jaroff, who holds Bachelor of Science degrees from the University of Michigan in both electrical engineering and mathematics, kept the story as unboggling for laymen as possible, but did not hesitate to make it fairly technical where necessary. He wrote the article from his own notes, with the help of Researcher Fortunata Sydnor Trapnell and major contributions from TIME bureaus. During an interview with Schmidt at Caltech, Jaroff was especially pleased when the astronomer let TIME in on a secret. "I looked through the microscope at the photo plate showing the latest quasar he discovered," says Jaroff. It is the newest and most dis tant, and our cover story is the first published account of this discovery.

For the cover painting, Artist Robert Vickrey studied about 100 detailed photographs of the skies to work out the background for his portrait of Schmidt. The whirling mass in the upper righthand corner is a spiral galaxy. To the left is a very bright star as seen through an optical telescope. In the right foreground, Vickrey renders a quasar, which may be recognized by the small jet stream spilling out from it at right. In showing Schmidt's head with its reflections receding into space, the artist tried to "give the feeling of infinity, the impression of an echo or radio waves being transmitted. The echo of the head, you might say."

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