Is our planet alone in its ability to host life? So far, it’s unique in the Solar System, which is dominated by apparently lifeless bodies, but it may not be unique in the universe. Astronomers have long speculated about the presence of extraterrestrial life elsewhere in the cosmos, but thanks to two planet-searching projects — ESO’s HARPS project and NASA’s Kepler mission — they are closer than ever to finding suitable candidate hosts orbiting other stars. Teams for both have announced intriguing discoveries in the last year, the latest of which includes detection by HARPS of a planet that is only 3.6 times the mass of Earth.
While Kepler is a space-based mission that searches for planetary transits — planets periodically passing in front of their host stars — HARPS (High Accuracy Radial velocity Planet Searcher) is part of the land-based La Silla telescope located in the Atacama Desert of Chile. The HARPS spectrograph looks for periodic shifts in the light from stars, tell-tale signs of gravitational tugs by orbiting planets. Most of the planets discovered by Kepler are orbiting distant stars; the planets discovered by HARPS, however, are orbiting nearby stars, and will be much easier to observe in follow-up projects to detect, for instance, spectral signs of water and other substances necessary for life as we know it.
The HARPS team at ESO recently announced the discovery of 50 new extra-solar planets, or exoplanets, including 16 planets designated as “Super-Earths.” A Super-Earth is a planet 2-10 times the mass of the Earth, but not necessarily rocky in composition; such planets could also be gas dwarfs without any discernible solid surface. One of the recently-discovered Super-Earths, designated HD 85512 b, is a rocky planet located just within the habitable zone around its parent star. The habitable zone is the orbital proximity to a parent star that allows the presence of liquid water on a planet’s surface. The holy grail, as it were, of planet searches is an Earth-like planet with the presence of liquid water — the essential ingredient for life as we know it. The mass of HD 85512 b is tantalizingly close to that of Earth — about 3.6 times greater. Professor Dimitar Sasselov, an astronomer at Harvard University (and the scientist who coined the term “Super-Earth”), speculates that such planets may be even better suited for life than our own Earth due to increased tectonic activity and stable rotation.
Astronomers point out that the frequency of exoplanet discoveries is increasing, and we seem to be on the verge of discovering that the universe is awash in potential hosts for life. So what does all this mean for Christians? Personally, I do not rely on the uniqueness of Earth to bolster my belief in a Creator. It may well be that many planets suitable for advanced life exist elsewhere in the universe, and such planets and life would be part of God’s purpose, as the many different continents and the variety of life on Earth are undoubtedly part of God’s purpose. Furthermore, the existence of many potentially life-supporting planets in the vast universe in no way diminishes the power of the fine-tuning argument, which says that the many physical constants and parameters that permit the existence of life as we know it — nearly 100 characteristics as identified by Hugh Ross — are so finely tuned that even the ostensibly atheist astrophysicist, Fred Hoyle, concluded “the universe looks like a put-up job.”