Modern astronomy tells us that we live on a more-or-less typical planet, orbiting a standard-issue star, lying in a decidedly run-of-the-mill galaxy. In short, we’re nothing special.

And yet, modern astronomy also assures us that our ordinary little world is part of something very special--a pageant of cosmic evolution stretching back some 13.7 billion years to the big bang itself. Indeed, most of today’s astronomical research is devoted to filling in the details of that story.

For example, evidence suggests that primordial gas began to condense into galaxies fairly quickly after the big bang, within a billion years or so. But precisely when and how did these first galaxies form, and how have they evolved since then?

Likewise, it seems that some of these galaxies accumulated so much gas at the core, that their central regions literally collapsed, forming gigantic black holes with millions or billions of times the mass of our sun. For a time, moreover, at least a few of these black holes continued to swallow up even more gas, thereby generating so much heat and light that we call them "quasars," and "active galaxies," and we can see them over vast distances. But precisely when and how did these black holes form? How common are they? And did they form in every galaxy? Is there actually a monster black hole in our galaxy?

Meanwhile, whatever fireworks might have been going on at the center, every one of these newborn galaxies was also beginning to light up around the edges with stars, as the primordial hydrogen and helium condensed to the point where thermonuclear reactions could begin. Those reactions, in turn, began to fuse the hydrogen and helium into heavier elements such as carbon, oxygen, silicon and iron. But precisely when and how did those first stars form? And precisely how has all that heavy-element production changed the composition of the universe over time?

NSF-supported astronomers are working to answer all these questions and more. In particular, the agency's National Optical Astronomy Observatory, together with the international Gemini partnership, offer astronomers some of the finest telescopes in the world for studying the universe in visible and infrared light. Its National Radio Astronomy Observatory, together with the Arecibo telescope in Puerto Rico, offer equally world-class facilities for probing the universe at radio wavelengths. The National Solar Observatory allows them to conduct detailed studies of the sun, which is not only the closest star to Earth but the key to understanding all the other stars. And the new National Virtual Observatory is attempting to democratize astronomical research by making the archived data available to everyone over the Internet.

Of all the projects that NSF supports, however, few have captured the imagination quite as much as the search for planets that orbit other stars.

Are We Alone? [Next]