Let’s set some perspective. Imagine standing in Washington, DC, and holding a grapefruit. If that grapefruit were the sun, the earth would be a grain of sand about 17 paces away. Our next closest star, Alpha Centauri, would be a clementine near Albuquerque, New Mexico.
That visual is amazing in and of itself. But let’s take it further: We have found nearly 4,000 of grains of sand orbiting stars much, much further away than that clementine in Albuquerque. And for each of those 4,000 grains of sand, we can also determine their size, composition, and whether they might be habitable.
How are we finding all of these “exoplanets”—planets beyond our solar system? And how can we tell if they might host life? That’s our focus as we continue our astrobiology series.
Finding the Grains of Sand
Several detection methods are detailed on the NASA Exoplanet Exploration website. The transit method is the most common, accounting for about 75% of the exoplanets detected so far. Precise instruments can measure how much an exoplanet dims the light each time it passes in front of its “host” star. Other methods detect tiny wobbles in the star due to gravitational forces. The amount of dimming (or the size of the wobble) helps scientists determine the size of the exoplanet.
Once an exoplanet is detected, scientists can focus other telescopes in that direction for further analysis. First, they try to find out if the planet is in a habitable zone—life, at least as we know it, cannot survive more than a small range of temperatures. So the planet must be just the right distance from its star. So far, only about 15 exoplanets have been clearly identified that fit these criteria, with the possibility of a couple dozen more.
Scientists also try to determine the composition of the exoplanet, a more complicated process. NASA describes it well, if you think about rainbows and barcodes. The light from any distant object includes a spectrum with a very distinct “bar code,” depending on what chemicals and materials exist on that object, or in its atmosphere. From this info, they begin to determine if a planet is rocky or gaseous, or if it has an atmosphere that reveals life signatures like water or carbon.
- NASA shows us how they detect exoplanets.
- Learn about exoplanets, habitable zones and signatures of life.
- To find aliens, perhaps we need to consider life as we don’t know it.
- In 1973, Carl Sagan addressed astrobiology in Rolling Stone.
- Tragedy drives one of the most tenacious hunters of earth-like planets.
- Check out the other posts in our series about defining life, aliens, astroethics, and what this all means for the church.
- An exoplanet researcher considers love.
- Br. Guy Consolmagno answers, “Does God love our intelligent life more than their intelligent life?”
Most of our search for life elsewhere begins with a common assumption—that it won’t be much different than life here. As a result, an unexpected word occasionally appears in the astrobiology literature: chauvinism. Planetary chauvinism. Carbon chauvinism. Even anthropic chauvinism.
Carl Sagan uses it in a 1973 Rolling Stone interview, readily admitting he’s a carbon chauvinist. But many scientists today challenge us to look wider, not to focus our search too narrowly. Alien life, as suggested last week, may or may not be much like earthly life.
My point here is not to pursue the science further, but to make connections to ministry and move toward two essentials of faith—Christ and love. How does our contemplation of life beyond earth inform (or at least reflect) the many chauvinisms in human affairs? How does it expand ideas like Galatians 3:26-28—that in Christ there is no longer Jew or Greek, male or female, maybe even earthling or alien? Do lessons like the Good Samaritan apply to how we love both our terrestrial and our extraterrestrial neighbors? And who do we consider a neighbor?
These are just a few of the questions that the search for extraterrestrial find life brings to the church. Exploring any of those questions with an open mind might just expand someone’s understanding of love and life in Christ.