Riccardo Giacconi; pioneered X-ray use in astronomy

Riccardo Giacconi, a Nobel Prize-winning scientist who was known as the founder of X-ray astronomy, a discipline credited with opening a new window into the cosmos, died Dec. 9 in San Diego. He was 87.

A daughter, Anna Giacconi, confirmed his death and said she did not yet know the cause. Giacconi was born in Italy but worked primarily in the United States, where he spent most of his life. At the time of his death, he was listed as a faculty member in the physics and astronomy department at Johns Hopkins University in Baltimore.

In 2002, the Nobel committee awarded Giacconi a share of the physics prize “for pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources.” The other half of the prize recognized Raymond Davis Jr. and Masatoshi Koshiba for “the detection of cosmic neutrinos.”

Giacconi was widely known as “the father of X-ray astronomy,” and the leader of the International Astronomical Union called him a determined, strong-minded visionary.

“World astronomy bears a huge debt of gratitude to Riccardo Giacconi,” IAU General Secretary Teresa Lago said in a statement.

For centuries, humans knew no more about the stars than their eyes could tell them. The starry universe seemed calm and immutable. But X-ray astronomy has helped create a new view, of turbulence, cataclysm, birth and death, creation and destruction.

Much of the modern understanding of the nature and dynamics of stars and galaxies, and the charged particles streaming between them, has been provided or supported by X-ray astronomy.

X-rays, although invisible to the eye, own just as firm a place on the electromagnetic spectrum as the light we can see. X-rays possess high energies and tell in turn of the high energy processes by which they are produced.

While they have streamed across the void of space for eons, only recently have scientists succeeded in capturing them, analyzing them and reading the messages that they carry about cosmic events at unimaginable distances.

The expansion of astronomy beyond visible light created a stir in science and beyond. Beyond the knowledge it provides of the cosmic environment in which we inhabit, X-ray astronomy is credited with yielding spinoff applications in industry, medicine, security and environmenºtal monitoring.

Blocked by Earth’s atmosphere, the X-rays emitted by the stars and galaxies have been detectable only by reaching high elevations or by launching observing equipment into space.

Giacconi and his colleagues developed telescopes suited to gathering the faintest X-ray signals from the far reaches of the universe. In addition to recognizing