Because black holes emit no radiation, they can never be directly observed. Their existence may be deduced only from the extraordinary effects black holes have on nearby objects, outside the event horizon. Lightman is attempting to predict the influence of black holes upon the distribution of stars, anticipating the day when such stellar patterns can be observed.

Some studies at the center are much more mundane. Jack Eddy, a visiting scientist at the Center, has shown how the amount of radioactive carbon in tree rings can be related to sunspots. Increased solar activity leads to warmer climates, Eddy says, raising the radiocarbon content of the rings. Another group of astronomers, working with radio telescopes designed to detect water vapor in remote parts of our own galaxy, found they could also use the radio telescope to measure the amount of water vapor in the earth's atmosphere. The method proved cheaper and more accurate than previous techniques, like taking samples with rocket probes.

The satellite Lageos, conceived and designed by scientists in the Center's division of geoastronomy, may provide a measure of continental drift. The satellite, now in orbit, is two feet in diameter, and is covered with 426 small mirrors. Scientists at two different ground stations direct lasers at the satellite. By precisely measuring the round-trip time of each beam, they hope to determine the distance between the stations to an accuracy of two centimeters--the distance many think Europe and North America drift apart each year. The researchers' accuracy is at about ten centimeters now. But most of the research at the Center looks much farther away from earth.

Field does not attempt to give pragmatic justifications for astronomy, although he does credit astronomy with starting the industrial revolution. He says astronomy provided the realization you could predict natural events--it offered "a few equations that had fantastic implications." But Field chiefly justifies the Center's work in romantic terms: "First and foremost, astronomy is an adventure--an intellectual adventure, but also an aesthetic adventure. Everyone can participate in one way or another." Field says, "Humanity loves astronomy--it's the wonder aspect. People don't wonder about bacteria, or the structure of the nucleus. It's a very primitive thing. I can't explain it, but it seems to be real."

In a convocation speech at the Center last May, Field suggested that astronomy may soon arrive at a major "intellectual synthesis"--"With an impact rivalling that of the Darwinian theory of biological evolution, it may be able to account for all the structures in the universe, from quasars to planets." Gursky, in the office above Field, is not so confident. He says, "If we thought we'd find an answer, we'd give up. We'd just publish it and go home."

In the meantime, research at the Center goes on, and the universe continues to expand. If you want to know what is happening in the sky this week, you can call the Center's Dial-a-Satellite phone, at 491-1497.