The search for worlds like our own Journal Item

The direct detection of Earth-like exoplanets orbiting nearby stars and the characterization of such planets— particularly, their evolution, their atmospheres, and their ability to host life—constitute a significant problem. The quest for other worlds as abodes of life has been one of mankind’s great questions for several millennia. For instance, as stated by Epicurus *300 BC: ‘‘Other worlds, with plants and other living things, some of them similar and some of them different from ours, must exist.’’ Demokritos from Abdera (460–370 BC), the man who invented the concept of indivisible small parts—atoms—also held the belief that other worlds exist around the stars and that some of these worlds may be inhabited by life-forms. The idea of the plurality of worlds and of life on them has since been held by scientists like Johannes Kepler and William Herschel, among many others. Here, one must also mention Giordano Bruno. Born in 1548, Bruno studied in France and came into contact with the teachings of Nicolas Copernicus. He wrote the book De l’Infinito, Universo e Mondi in 1584, in which he claimed that the Universe was infinite, that it contained an infinite amount of worlds like Earth, and that these worlds were inhabited by intelligent beings. At the time, this was extremely controversial, and eventually Bruno was arrested by the church and burned at the stake in Rome in 1600, as a heretic, for promoting this and other equally confrontational issues (though it is unclear exactly which idea was the one that ultimately brought him to his end). In all the aforementioned cases, the opinions and results were arrived at through reasoning—not by experiment. We have only recently acquired the technological capability to observe planets orbiting stars other than Research and Scientific Support Department, ESA, European Space Research and Technology Centre, Noordwijk, the Netherlands. Universidad Autonoma de Madrid, Madrid, Spain. Max-Planck Institut für Astronomie, Heidelberg, Germany. Space Research Institute, Austrian Academy of Sciences, Graz, Austria. Université Paris-Sud, Orsay, France. Department of Radio and Space Science, Chalmers University of Technology, Onsala, Sweden. Istituto Nazionale di Astrofisica, Rome, Italy. Royal Observatory Edinburgh, Blackford Hill, Scotland. Space Science & Technology Department, CCLRC Rutherford Appleton Laboratory, Oxfordshire, UK. Landessternwarte, Heidelberg, Germany. Leiden Observatory, Leiden, the Netherlands. University of Bordeaux 1, Bordeaux, France. The Open University, Milton Keynes, UK. Laboratoire d’Astrophysique de l’Observatoire de Grenoble, Saint Martin d’Heres, France. Institut d’Astrophysique et de Geophysique, Liège, Belgium. SRON, Netherlands Institute for Space Research, Utrecht, the Netherlands. Observatoire de Paris-Meudon, Laboratoire de l’Univers et ses Théories, Meudon, France. Department of Physics and Astronomy, University College London, London, UK. Payload and Advanced Concepts Division, ESA, European Space Research and Technology Centre, Noordwijk, the Netherlands. NASA Exoplanet Science Institute, California Institute of Technology and Jet Propulsion Laboratory, Pasadena, California, USA. Jet Propulsion Laboratory, Pasadena, California, USA. NASA Goddard Space Flight Center, Greenbelt, Maryland, USA. United States Naval Observatory, Washington DC, USA. Lunar and Planetary Laboratory, Tucson, Arizona, USA. Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA. ASTROBIOLOGY Volume 10, Number 1, 2010 a Mary Ann Liebert, Inc. DOI: 10.1089=ast.2009.0380