Kepler is a planet hunter. The NASA craft stares at a small parch of sky containing about 150,000 stars and waits for something to pass in front of a star, blocking a tiny fraction of the star’s light.
You can tell the mass of the star, its distance, and its energy output using relationships with a star’s color worked out a century ago and most artistically depicted in a Hertzsprung-Russell diagram. You can then derive information about the object blocking the star’s light from measuring how much light gets blocked and for how long. There’s a lot of uncertainty about how large the blocking object is because you can’t see the object itself, so you have to make guesses about angles. However, you can tell whether it’s planet-sized quite easily, and then come up with constraints on its orbit around the star that tells you, in turn, things about the planet’s own temperature.
As reported in New Scientist , Kepler has so far found 1235 planets, of which 68 are small rocky worlds like earth (as opposed to gas giants like Jupiter). Fifty-four of the rocky worlds may be in the habitable zone around a star where temperatures permit liquid water on a planet’s surface.
Extrapolating from that small patch of sky and the limited chance to be located at the lucky angle to see planets cross a given star’s disk, the Kepler team estimates that about half of all stars have planets and about 1 star in ten has an earth-sized planet. About 8% of all stars would have an earth-sized planet in the habitable zone. Indeed, those statistics suggest that there could be 1,000,000,000,000,000,000,000 earth-like planets out there in the visible universe, according to the report.
Since astronomers, as well as physicists, like to play theologians on television, the AAAS meeting also had a conference panel on what the theological implications would be for major world religions. Jennifer Wiseman of the AAAS Science and Policy Office in Washington presented the special issues for Christianity, which, not surprisingly, relate to the special nature of Christ as the incarnation of God.
To quote from her presentation’s abstract:
“Christian thought throughout the ages has had mixed reactions to the idea of life elsewhere. While most Christian traditions of today can embrace a life-filled universe, especially one of simple life, as an extension of the abundant good gift of life on Earth, there are certain central Christian tenets that require special consideration. In particular the doctrine of “incarnation” – God becoming human to help and redeem us– deserves some special thought if there are many other intelligent life forms out there! Recent gatherings of scientists and theologians, such as those sponsored by the Pontifical Academy of Sciences, affirm the eagerness to consider these issues.”
Now, Mormonism didn’t get its own discussion at the AAAS meeting, but its theology of the physicality of God and the nature of the Incarnation makes its understanding of Jesus at least as different from that of mainstream Christianity as other world religions when it comes to intelligent life elsewhere.
Specifically, conventional Mormon interpretations seem to say that intelligent life has to be human in form, and imply that the fall of humanity was part of the plan of salvation. Hence, the death of Jesus is required for the return to God’s presence.
When there is one world where human life exists, the situation is fairly clear (although in Mormonism, Jesus took His testimony of His own resurrection beyond Judea). But what are we to make of a multitude of human worlds throughout space?
Must Jesus be born and crucified on each of them? Is baptism for the dead a much larger project than pictured? Or would detection of intelligent life elsewhere (especially in non-human form) pose a more fundamental shock for Mormon theology than for the rest of Christianity?