New planetary discoveries renew questions about extraterrestrial life

Greg Rakozy via Unsplash 

What is the chance that extra-terrestrial life exists? It is a question that we astronomers often get asked, and I always respond by saying that we have no idea. To predict the probability of something occurring, you need to start with some relevant, prior knowledge. For instance, meteorologists can figure out how likely it is to rain tomorrow because they already have lots of data about weather patterns. But in the case of predicting how common it is for life to arise in the universe, we currently only have one datum: the existence of life on earth. That’s just not enough.

However, we are getting closer to having the extra data we need. On June 19, NASA announced that its Kepler space telescope team had identified 219 new planet candidates. This followed on the widely-covered February report by another team of scientists that they had discovered seven earth-sized planets, all orbiting a single star named “TRAPPIST-1.”


We assumed that planets orbiting other stars would look like the planets in the solar system. What we have found is that reality is much richer than we imagined.

What makes these exciting news stories is not the discovery of planets per se—thousands of extra-solar planets have been cataloged over the past 25 years—but that a few of them belong to a much shorter list of planets that are potentially habitable. They are similar in size to earth and, crucially, orbit their stars at a distance that could result in just the right temperature to host liquid water, a prerequisite for the only kind of life we know. The Kepler team has 10 new candidates of this kind (which still need to be followed up), while TRAPPIST-1 can boast three confirmed planets in the sweet spot.

According to Vatican Observatory astronomer Paul Gabor, S.J., an expert in planetary detection, the TRAPPIST-1 discovery is particularly tantalizing because so many Earth-sized planets have been found around such a small star: TRAPPIST-1 is only one 12th of the sun’s mass, roughly the size of Jupiter. “Thirty years ago,” Father Gabor comments, “we assumed that planets orbiting other stars would look like the planets in the solar system. What we have found is that reality is much richer than we imagined.” This richness has its benefits. Because TRAPPIST-1 is so small and dim, its habitable zone is much closer in, and its planets consequently complete their orbits in a matter of days. Detecting planets with such short orbital periods is more practicable because you do not have to observe their stars for long periods of time. Other small stars could thus provide rich terrain for Earth-like planet-hunting.

Still, to return to my initial point, we have no idea whether there might be life on these planets. They could be barren rocks with empty oceans. But scientists are already forecasting that if any of them have atmospheres, the James Webb Space Telescope, due to be launched next year, will be sensitive enough to detect atmospheric chemicals typically produced by biological processes, like oxygen and methane. And that could finally give some empirical grounds for inferring the existence of extraterrestrial life. Father Gabor says that such results would probably be “tenuous”—it is a really hard measurement to make—but that it could encourage funding for more advanced space telescope instrumentation to investigate further.

Right now, all we can do is speculate about what alien life might be like. And we cannot merely extrapolate from our knowledge of life on Earth. The bodies of alien species could be wildly different. Further, we cannot say whether evolution on other planets would result in higher forms of life analogous to those we have on Earth. It could be that life is common but intelligence is rare. And even if there are other rational creatures, their patterns of thought could be totally different from ours. Last year’s film “Arrival,” for instance, imaginatively explored the difficulties that might be involved in communicating with intelligent aliens.

These are only some of the questions to ponder about alien life, and that is before you even get to the religious issues—before you can ask the titular question of the recent book by Father Gabor’s colleagues, Guy Consolmagno, S.J., and Paul Mueller, S.J., Would You Baptize an Extraterrestrial? (Their answer in brief: It depends.)

So, it is too early for the Holy See to erect a Dicastery for Extraterrestrial Life. But at least in the meantime the Catholic faith has already made a concrete contribution to the search for alien life, albeit indirectly: The Belgian leaders of the recent study say that the mission acronym TRAPPIST was inspired by the beer brewed by the monks of the same name.

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J Cosgrove
10 months ago

Life is so incredibly improbable that it is extremely unlikely that it ever arose in the universe naturally. It could arise as the result of a massive intelligence but not naturally. Of course that begs the question as to the origin of the massive intelligence.

Also Earth is so rare and conducive to life that it is unlikely another such planet like it exists in the universe. The author and any interested readers should google "Privileged Planet" and watch it on Youtube.

Since this film was made more characteristics of the Earth have been discovered that make it a even more remarkable planet.

Jonathan Lunine
10 months ago

Rather than making such unsubstantiated claims (what evidence do you have that your first sentence is even reasonable?), let's keep looking. This article covered the astronomical search; within our solar system both Europa and Enceladus have subsurface oceans, and in the case of the latter, sampling by the Cassini spacecraft of a plume of gas and ice emitted from the ocean suggests the ocean may be habitable. If a future mission finds evidence of microbial life in Enceladus, that would certainly raise the stakes on finding intelligent life in other planetary systems.

J Cosgrove
10 months ago

Nothing is unsubstantiated. I suggest you read about how complicated even the simplest life is and how improbable it could happen.

Nobody is suggesting not to keep looking.

But truth has to be sought, not wishful speculation.

Bruce Snowden
9 months 4 weeks ago

Hi, Mr. Cosgrove, I understand that posting here is not simply an opportunity to freely express ideas and opinions, even though there's room for some of that too. I think its more about using this space as teaching moments, validating well rooted information and expanding thereon. I like how you do that but find myself doubting your asserting that, "Life is so incredibly improbable that it is extremely unlikely that it ever arose in the universe naturally."

On the contrary I believe that natural life arose naturally, a second action needed to produce human immortality, God the Sower creatively scattering seeds of life through the infinity of space allowing natural dynamism to take over, to take root. You see, its all about seeds without which there would be no life, no anything. So yes, I'm eager to find out that ever more perfected devises of human searching will reveal hiding places of new forms of life, or perhaps identical to life as we know it. How exciting that would be!

J Cosgrove
9 months 3 weeks ago

Hi Mr. Snowden,

My assessment is based on science. I have no problem with the possibility that life arose naturally. But it seems beyond any process we know exists except one, specific design. There is a very technical book called "The Signature in the Cell" written by Stephen Meyer that discusses it in detail.

There no known natural process that could have created life. Lots of speculation which all fall apart on scrutiny. Doesn't mean it didn't happen but extremely, extremely unlikely. People often assume that life is simple and that was the belief until the last century when scientists started unraveling how complicated it is, probably the most complicated thing in universe. I purposely did not get into much detail because it would get too complicated but just say that producing a Shakespeare' sonnet by randomly hitting keyboard keys would be easier.

By the way there is no agreed upon definition of life. All attempts fail to encompass everything we see in life. It is something I have been reading about for over 20 years since going to a Catholic sponsored conference on it in New York City.

Theologically, few have speculated on a God that designed such a universe. It seems to point to a God that built in interaction with His creation. A God we can pray to and consequently would affect His creation on an ongoing basis. Just as the Catholic God does.

Bruce Snowden
9 months 3 weeks ago

Hi Mr. Cosgrove, Thanks for your interacting response to my far less involved commentary than yours. You are an interesting contributor, obviously well-studied. Let me simply add that, yes, I do believe that God builds in an ongoing way, an interacting creation, one thing depending on another, purposefully orchestrated evolutionally under the fertility of the Divine baton, referencing the Jesuit astronomer George V. Coyne, S.J., who called the universe "fertile." Seeds and fertility link. Coyne further says, "God gave the universe its own creativity, its own dynamism and he works with the universe rather than dominating it." In a word, according to Father William J. O'Malley also a Jesuit, "Divine wizardry is in the power and fecundity of the universe itself." That's why I would dare suggest that seeds of life are scattered throughout the "multiverses" of the incalculable fling of celestial space. Again, thanks for responding,

Dimitri Cavalli
9 months 3 weeks ago

I think science fiction has projected many people's hopes and conditioned us to assume the following: (1) aliens are likely technologically superior to us (which can't be proven because we don't know); (2) are mono-lingual (unlike humans who continue to use hundreds of languages and dialects); and (3) will have one planet-wide government and will be united politically (unlike us).

If one believes that matter and life came into existence by chance and are just the product of random evolution, then one of the possibilities is that despite the infinite nature of the universe, we're the only ones here. If aliens do exist, then another possibility is that we're the most technologically advanced species in the universe and, perhaps in the distant future, we'll be visiting less developed alien civilizations, abducting its residents for experimentation, erasing their memories, and screwing up their lives.

Anyone notice that atheist scientists such as the late Carl Sagan, Richard Dawkins, and Stephen Hawking use similar philosophical arguments to prove (or suggest) the existence of extraterrestrial life that are often used to prove (or suggest) the existence of God?

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