Turning Point: Seven Earth-size planets that could potentially harbor life are discovered orbiting a star.
The more we gaze out into the universe, the more we suspect that someone may be gazing back. The possibility became even more intriguing earlier this year when an international team of astronomers discovered at least three planets in the nearby Trappist-1 star system that might be capable of supporting life.
The discovery of life on another world would change our own. It would fundamentally change the way each of us feels about being a living thing in the cosmos. And as always seems to be the case with discoveries in astronomy, it would be humbling.
You probably know of a few famous examples. Copernicus showed that Earth and the other observable planets move around the sun, not the sun around Earth. Galileo showed that the moon is covered with enormous craggy peaks and rugged valleys. Astronomers from all over have shown that our sun, our lifegiving star, is not any big deal; it's one among billions. Even our galaxy is hardly unusual. Billions of those, too.
Just imagine finding a planet with a comfortable surface temperature and an atmosphere with substantial amounts of not only water vapor, but also methane, the main component of natural gas. Although, nominally, there is more than one way to produce it, the main way we get new natural gas and organic molecules is by the natural processes of organisms. We're talking about microbes, either the ones inhabiting seas and swamps, or those that live inside creatures like us.
So where do we look if we want to find microbes? Better yet, how do we look? Finding a planet not too different from our own would be a logical place to start. What sets the Earth apart from all the other planets that we know well — Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune — is its distance from the sun, which enables it to have liquid water. It has a suitable atmospheric pressure and surface temperatures between liquid water's freezing and boiling points, 0 to 100 degrees Celsius (or 32 to 212 in those quaint "Fahrenheit" degrees).
The scientists who found the Trappist-1 system were searching for just that, and they found not one, but seven exoplanets — planets not in our solar system — orbiting the star. Three seem well-suited to having liquid water on their surfaces.
In the coming months and years, astronomers will refine the search, hoping to tease out the critical spectral data that would tell us whether there is water vapor in these remote atmospheres, as well as liquid water in an ocean.
Still, alien visitations are very unlikely. According to all the physics that we understand, there is no practical way for us to travel, in astronaut fashion, to another star system. There is just too much space in space. A spaceship would take tens of thousands of years to reach Proxima Centauri, the star closest to our own. It would be many times that distance to Trappist-1, which is 40 light years away. And despite decades of listening and looking, we haven't heard an intelligible signal from the cosmos. (Insert your own joke about Earthling politics here.)
Any signal, any twinkling, any beam from a distant star system would unleash a barrage of questions: Do they have written language? Do they have farms? Do they have sex? Do they need those things? Are they coming to visit? And then, what do we do if they are on their way? What would they think of us? Are we worthy correspondents, communicating across the vastness of space? Or, are human affairs too petty and trivial to concern another race of beings?
If these aliens could travel here, they probably wouldn't think much more of us than we think of termites: "These humans sure are interesting. They build [the equivalent of] complex living spaces (mounds) with only rudimentary instructions (constitutional governments, oligarchies, technocracies)."
But that would be about it. After all, we seem to be in the midst of making our home world unlivable for billions of our own kind, let alone the dozens of species in danger of extinction. If we got a signal from out there, would it change our attitudes?
The researchers of the Transiting Planets and Planetesimals Small Telescope (Trappist) program are said to be peace-loving deep thinkers, just like their program's namesake, the Trappist monks. We could learn something from them.
The world's military budget is about $1.7 trillion. With the right inspiration — say, keeping our planet whole long enough to see what's at the other end of that hypothetical alien signal — we could cut that in half and use the rest to unite, protect and strengthen our ailing Earth rather than tearing it apart.
Bill Nye is CEO of the Planetary Society, a nonprofit organization dedicated to the exploration of the solar system.