Tuesday, May 21, 2013

Planet Bruno

In the year 1600, Giordano Bruno went up in smoke in the Campo de' Fiori in Rome, the Field of Flowers. Among his many theological transgressions was the heretical belief that the stars were other Suns with other inhabited planets. How strongly the latter belief figured in his condemnation is a matter of controversy, but certainly it was part of the unorthodox stew Bruno held in his head.

Today, a statue of Bruno stands, dark and brooding, on a pedestal in what is now a busy market square, erected by Freethinkers in the 19th century. Not far away is Saint Peter's Square, which remains an epicenter of orthodoxy. The Church doesn't burn heretics anymore, but it doesn't tolerate dissent lightly. Just ask the American Catholic nuns who have lately run afoul of the Vatican.

Many years ago, I visited the Campo de' Fiori and made my nod to the man who entertained one of the most daring ideas of all time: a myriad of Suns, a multitude of inhabited worlds. Today you can visit with Google Street View without leaving your easy chair.

Meanwhile, astronomers are busy putting Bruno's ideas to the test of empirical verification. They have long since determined that the stars are indeed other Suns, or rather that the Sun is a typical star. Now they are engaged in a pell-mell search for extrasolar planets. Upwards of a thousand planets around other stars have been verified, and hundreds more are discovered every year. It now seems likely that most, if not all, stars have planetary systems. And a few of these are in the so-called habitable zone, defined as "the annulus around a star where a rocky planet with a CO2-H2O-N2 atmosphere and sufficiently large water content can host liquid water on its solid surface."

Next comes detection of a planet with the chemical signature of life. The May 3 issue of Science has a special section on how this might be done, and in the not so distant future. If and when it happens, an obvious name is waiting for the planet.