Would Extraterrestrial Intelligent Life Spell Doom for Christianity?

By Guillermo Gonzalez

On February 1, 2011, NASA’s Kepler mission team announced that they had discovered 1,235 candidate planets orbiting other stars (exoplanets). Launched on March 6, 2009, the Kepler mission’s primary science objective is to determine the fraction of Earth-size planets that orbit within the circumstellar habitable zones (CHZs) of their host stars. A terrestrial planet within the CHZ can maintain liquid surface water, a prerequisite for life.

Kepler searches for planets using the photometric transit method, whereby a star dims slightly as a planet crosses between us and the star. This method has been employed successfully with small ground-based telescopes since 1999, but the Kepler telescope is much more sensitive thanks to its location outside Earth’s atmosphere.

What made this announcement truly historic was the discovery of three to six exoplanet candidates less than twice the size of Earth within the CHZs of their host stars. So, now we know for the first time in history that planets comparable in size to Earth orbit other sun-like stars. How common are they? Based on observations of more than one hundred fifty thousand stars during Kepler’s first four months of operation, astronomers estimate that 1 to 3 percent of sun-like stars have planets less than twice the size of Earth and within their CHZs.1 This result is still preliminary, given the short duration of the observations to date, but ongoing observations in 2012 and 2013 should give us a solid number.

These discoveries have brought back to the fore the ancient questions of life beyond Earth and our status in the universe. Are Earth-like planets rare? Are we alone, or might the universe be teeming with life? What are the broader philosophical and theological implications? We can give answers to these questions with varying degrees of confidence. Let’s take each in turn…


Would Extraterrestrial Intelligent Life Spell Doom for Christianity?