A biblical poet wrote, “The heavens declare the glory of God; the skies proclaim the work of his hands.” (Psalm 19:1). That poet, writing three thousand years ago before the discoveries of modern astronomy, didn’t know the half of it.
The science fiction author Isaac Asimov once wrote a novel with the title, The Stars Like Dust. That title severely underestimates the actual number of the stars. Perhaps if the title had been reversed it would have been more accurate.
Go to the beach and sit down on the sand—or if no beach is nearby, find a child’s sandbox. Pick up a handful of sand and bring it up to your face so you can see the individual grains; let them trickle through your fingers. Look up and down the beach at all the sand and imagine trying to count every last tiny mote of it.
Then, come evening, lie on your back and stare up at the black sky dusted with gleaming pinpricks and realize the unfathomable vastness of the universe: there are more stars in that sky above your head than there are grains of sand on all the beaches and in all the sandboxes in all the world.
The total number of confirmed planets beyond our own solar system, as of today (when I wrote this blogpost) is 1827. The latest HIP 116454b, was added to the list on December 18. It is a gas giant that was discovered by the Kepler spacecraft during its extended K2 mission. It is about 180 light years away and about two and a half times bigger than Earth, circling a K class star 3/4ths the size of our sun. Its “surface” temperature is estimated to be about 782 degrees Fahrenheit (417 Celcius). Probably not likely to harbor any life.
The technology that allows astronomers to find planets around other stars is still severely myopic, with very little detail beyond mass and orbital details discernable. New and better instruments will come along, assuming adequate funding for NASA, that will someday allow us to gather the more detailed information that will help us find what we want most of all: Earth clones with biospheres, along with evidence of intelligent inhabitants.
Our home galaxy, the Milky Way, contains at least 200 billion stars (estimates range between 100 and 400 billion. In this blog posting for today, I’ll aim for the middle). If only five percent of those stars have planets (more likely, its closer to 100 percent, but for this blog post I’ll be excessively conservative), that means that 10 billion solar systems exist beyond our own. And yet, that’s just the stars within one galaxy. The observable universe contains at least 100 billion galaxies averaging the size of our own Milky Way.
What does all that mean? That the number of planets in the universe is far vaster than the number of stars. And even odder to think about: if even only one percent of those planets are capable of harboring life, and if only one percent of those have intelligent beings on them who can look up at their night skies and wonder about what they are seeing—the number of civilizations in the universe will be uncountable billions.
There are 86,400 seconds in a day. There are about 31and a half million seconds in a year (if you figure a year at 365.25 days). If you were to start taking a photograph of each star in just our galaxy, and took a photograph once every second, twenty-four hours a day, seven days a week, with no time off for sleeping or anything else, it would take you over thirty-one years just to photograph the first one billion stars. To get photos of all the stars in the Milky Way Galaxy, given that there are 200 billion of them, would take you over six thousand years: the length of all recorded human history. Then you’d only have another hundred billion galaxies to go, just in the visible universe (and the universe is much larger than the tiny bit of it—a bubble about 30 billion light years across—that we can see). And that’s with spending only a single second on each star.
One can devote an entire lifetime to the study of a single subject, for instance Russian literature. And one could specialize further and devote oneself to the work of just one Russian author, say Dostoyevsky. Or maybe you’d like to devote yourself to the study of Russian history, perhaps twentieth century Russian history (I took a yearlong course in that in college as an undergraduate). Most of us in high school or college took a course in World Civilization, which covered the entire history of our planet in a single year. Not much detail in a class like that.
Now imagine trying to cram the history of multiple civilizations into your brain: the billions that lie scattered across our skies.
I marveled at the grains of sand trickling through my fingers one sunny sum
mer day not that long ago, while the waves were roaring in the background. And I couldn’t help imagining how they represented worlds scattered across endless oceans of night, each with waves and sunny beaches that I would never know.