Is there life on other planets? People have wondered over that question for centuries — and still do, as evidenced by the runaway popularity of the movie Signs this summer.

For the past 40 years, since the technology of large radio telescopes became available, astronomers have been listening in on nearby stars, hoping to pick up signals from intelligent extra-terrestrials. The U.S. government funded these studies for a while, but when no signals were picked up after three decades of listening, taxpayer support dwindled and eventually dried up altogether. However, so broad was the interest in the Search for Extra-Terrestrial Intelligence (SETI) project that private investors stepped in and provided millions of dollars to fund the search. It continues to this day.

SETI received a great boost in 1995, when astronomers confirmed the first planet orbiting an adjacent sun-like star. (The planet was not seen directly: It was discovered by detecting a “wobble” in the path of the star.) Since 1995, reports of planets shown to be orbiting sun-like stars, just as the earth orbits its sun, have been coming in at a steady rate. The count reached 100 this past July 1.

The late Cornell astrophysicist Carl Sagan probably did more than any other scientist to popularize the possibility of life on other planets. Through his writings and his popular TV show Cosmos, Sagan raised people's awareness about the immensity of the universe and the vast possibilities that may exist for life to appear.

In 1985, Sagan published a novel, Contact, describing the chain of events that might be set in motion by the discovery of intelligent life on other planets. Sagan's story is much more than fiction, however. It contains a respectful invitation to consider how science and religion might profitably interact. While the characters in the book are attempting to devise a response to the aliens, it is not only the scientists who are asked for an opinion: There is a place for religious figures to offer appropriate insights.

For a book authored by someone who was widely regarded as a dogmatic atheist, it is remarkable how well-balanced the characters in Contact actually are. There is no attempt to caricature the representatives of religion or to portray the scientists as universally enlightened. There is a mixture of good and bad on both sides of the religion-science divide, just as exists in real life.

Intelligent Life Elsewhere

Underlying the novel's plotline is the question: Is there really a God and, if so, what can science find out (and say) about him? Sagan does an intriguing job of outlining what a scientist might consider to be proof of God's existence in the natural world. The main character in Contact performs a mathematical test for God's existence, and Sagan's description of its results seem to suggest that he, himself, believed in the existence of God. This, of course, flies in the face of the popular perception of Sagan as a sort of “atheist-in-chief” among scientists.

The fact that Sagan was able to face squarely the question, “Is there a God?” is in marked contrast to what happened in the 1997 movie version of Contact(starring Jodie Foster and Matthew McConaughey). By the time the movie was in production, more than 10 years after the book appeared, Sagan, terminally ill, was in no shape to advise the screenwriters. The latter took great liberties with the text, slanting the story in a very different direction than the book had taken. The movie is unabashedly anti-religion — or, more specifically, anti-Christian; the Christian ministers in the movie are portrayed in a decidedly negative light.

Apparently, certain nonbelievers (including the screenwriters for the movie Contact) are convinced that religious people have no room in their belief system for the possibility of life on other planets. Religious believers are supposed to imagine that God “favors” human beings to such an extent than he could only have made intelligent life here, on earth. If we ever contact aliens, it will spell the end of organized religion as we know it, for no organized religion can accommodate a teaching about life on other planets.

Who's to say there are not many intelligent races of being in the univers?

Wrong again. At least one theologian laid the groundwork for Catholics to accept alien life forms within the context of the faith. And we are not talking about a modern theologian who just happens to be keeping up with the current scientific literature. No, the theologian in question, Thomas Aquinas, did his work more than 700 years ago, while he was a theology professor at the University of Paris.

What did Aquinas have to say that is relevant to life on other planets? Since the first public profession of faith in Christ's divinity — “You are the Christ, the Son of the living God” (Matthew 16:16) — Christians have known that there is more to Christ than meets the eye. In Christ is found the fullness of humanity as well as the fullness of divinity.

It took a few centuries for the Church to figure out how Christ can be simultaneously fully divine and fully human. But the Church Fathers finally decided, at the Council of Ephesus in 431, that the best human language could offer to explain the mystery was to condense it down to what is called the hypostatic union.

When Aquinas discusses the hypo-static union in his Summa Theologiae, he makes the following point: It is inevitable that the second person of the Trinity possesses at least one nature (the divine nature). As long as there is only one nature and one person (let us refer to this as the one-in-one case), there is no mystery involved. The mystery enters when we go beyond the one-inone to the two-in-one teaching of Ephesus. It is indeed a profound mystery of the Catholic faith how Christ can be one person with two natures.

And yet it is part of the story of Redemption that one of the divine persons took on human nature in order to redeem human beings.

Here is where Aquinas’ argument takes a surprising turn. He points out that, once a divine person chooses to take on more than one nature, there is no reason why that person should be limited to having merely two natures. There is, in principle, no reason why the divine person should not have the ability to take on three, four or many natures — all united in an expanded version of what we refer to in our poor human language as the hypostatic union.

Interplanetary Redemption

In view of the modern interest in life on other planets, this insight of Aquinas must be considered remarkable. For if there are rational creatures on other planets, endowed with free will, then it is possible that sin exists on other planets. And, if so, those fallen beings will require redemption just as we humans do. Presumably, the second person of the Trinity, through whom all things were made and for whom all things were made (Colossians 1:16), would be the one to effect the redemption of those fallen beings also. And how would he do that? By taking on their nature in addition to his own divine nature. His person would remain single (the second person of the Trinity), but he would perform his actions in that other world through the nature of the rational beings of that other world.

Using this insight of Aquinas, we Christians do not have to fear that “our God is too small” to accommodate the possibility of alien life. Instead, we can rejoice that it may not be only ourselves who can claim: “In him we live and move and have our being” (Acts 1:28). Perhaps there is another race of beings who can rightfully make the same claim. Who's to say there are not many such races?

To be sure, this race — or these races — may not live on any of the 100 sun-orbiting planets known to today's astronomers. But if such races exist, they must live on some planet somewhere. And someday, if God wills, we may be permitted to make contact with one of them.

Wouldn't that be the day! If God wills it, among the people who would rejoice we will see two former university professors — one from Paris, the other from Cornell.

Dermott J. Mullan writes from Elkton, Maryland.