Kepler On the Way to Search for Earth-Size Planets
The long-awaited launch of the planet-hunting Kepler spacecraft was successful Friday night, announced the Jet Propulsion Laboratory. Named for the 17th-century German astronomer-mathematician Johannes Kepler, the spacecraft will stare at 100,000 stars for over three years, looking for variations in their light that indicate the presence of planets. Follow-up studies may determine if some of these planets are earth-sized and orbit within their stars’ habitable zones. For more information on the mission, tour NASA’s Kepler website.
Johannes Kepler, a strong Lutheran Christian (see our online biography), speculated about space travel and the possibility of other worlds. In addition to his many scientific works on astronomy, optics, physics and mathematics, he wrote a fictional work, Somnium, or The Dream (see analysis by Gale E. Christiansen, which provides biographical background leading up to the writing). The book described what astronomy might be like from another world—our moon. Some have considered it the first work of science fiction. Kepler’s fanciful story considered the relationship of the inhabitants of the moon to their geography. Kepler revised the work for many years and was working on it when he died; the final version was published posthumously in 1634. Kepler’s three laws of planetary motion form the basis for celestial mechanics and space flight, of which his namesake spaceship is one of his many scientific legacies.
It is difficult to assess what Kepler thought about a plurality of worlds with intelligent life. The point of Somnium was to imagine astronomy from the surface of the moon. His extensive footnotes showed more interest in scientific aspects of habitability on another world than the philosophical and theological ramifications of his fictional beings. The moon was no longer a perfect celestial sphere; it was becoming a physical object orbiting the sun according to the laws he had developed within the new Copernican framework. Kepler did not make his fictional work a treatise on theology or a social commentary. But since he did take an existing genre of fiction about space travel into a new level of scientific rigor, and since he did speculate about habitable worlds other than our own, the Kepler mission is rightly named in his honor.
Several hundred extrasolar planets down to the size of Neptune are now known to exist. It seems rational that the size range of orbiting bodies is a continuum, but we really don’t have any hard data on how many Earth-class planets are out there. They could be common, they could be rare. Either answer is interesting. Alan Boss told Nature News that if Kepler comes up empty-handed it would be astonishing. Settling this centuries-old question with evidence once for all is a good thing for everyone, and we welcome it. More and better data are always preferable to speculation.
Assuming the Kepler mission is successful, and the idea of a universe filled with Earth-size planets gains a basis in empirical evidence, how will this affect philosophy and theology? Earth-size planets alone do not imply life, much less intelligent or sentient life. Future missions like the Space Interferometry Mission or Terrestrial Planet Finder may be able to sharpen our vision further. Advances in remote sensing may detect biosignatures, such as atmospheric gas ratios that would be surprising under natural conditions. Evidence for sentient life on another world would require an intelligent radio message (but even then, how would one ever prove it isn’t a lying demon?)
Assume, for the moment, that the conclusion of beings like us on other planets becomes inescapable. A Biblical worldview allows for that. Christians have not been idle in giving that possibility deep thought; the science fiction works of C. S. Lewis are a case in point. Some evolutionists are chomping at the bit to disparage Christianity, assuming that the Bible only allows for Earth to be the special abode of creatures made in His image. A million other inhabited worlds would cast severe doubt on the claims of Christianity, they think. But the Biblical Creator is far too transcendent and majestic for such a parochial view. Angelic beings, such as those described in the Bible, may already obey God’s bidding unrestricted to realms beyond earth. And a God capable of designing millions of species on our planet is certainly not lacking in power and creativity to decorate other worlds with living things appropriate to their geography. If evolutionists think such a discovery would support their naturalistic worldview, they need to read our online book and let it sink in that the chance origin of even one useful protein molecule is so unlikely, it would have less than a vanishingly small chance of ever happening anywhere in the universe. Read the book and see how even under the most generous conditions, getting a set of proteins or genes for a living cell is so unlikely, it is laughable to even entertain the thought. If life is out there, it was created.
For the time being, though, in the absence of proof of sentient physical life on other planets like ours, wasting time on unknowns is superfluous. An eventual discovery would threaten Christianity no more than did the discovery of a New World inhabited by strange civilizations. We would want to understand them and tell them of God’s grace. No future discovery will undermine our awesome wonder and appreciation for our privileged planet and the historical evidence for what God has done here. If we are alone, that would be no less thought-provoking. It might only mean we are alone now. The Bible describes a new heavens and new earth with eternal life. That could conceivably include space travel without physical limits. Earth may just be our testing ground. With bodies fit for the new creation, as the Bible describes (e.g., I Corinthians 15), freed from the limitations of gravity and other physical restrictions, who knows? We could be the skywalkers of galaxies far, far away, singing praises to the one true God from locations throughout the cosmos.
Enough speculation. Back to the real world. There’s a lot of work to do. Johannes Kepler set a good example. On occasion, his mind roamed among the stars, but he was always a man of responsibility, character, integrity, faithfulness, honesty and love. The Spirit of Christ anchored his soul in the heavens, and empowered his walk on the earthy ground.