In the last decade however, we have made enormous advances in the field of exoplanet studies. Telescopes on the ground have become sensitive enough to discern the faintest stellar “wobbles,” as orbiting planets tug gently against their gravitational bonds. With the National Science Foundation’s Atacama Large Millimeter Array, and the Hubble Space Telescope, we have peered into interstellar clouds where new planets are forming and have detected the presence of all the elements necessary for life.
New discoveries are coming fast and furious. On February 23, 2017, NASA announced that a nearby star system, TRAPPIST-1, has seven planets orbiting it, three of which lie within the star’s “Goldilocks zone,” making them potentially habitable. And on April 19, the Harvard Smithsonian Center for Astrophysics and the European Southern Observatory announced the discovery of a “super Earth”—a rocky, planet 40-percent larger than Earth, orbiting a red-dwarf star just 39 light years away. Indeed, we are finding thousands of planets orbiting other stars. Data from NASA’s Kepler Space Telescope suggests that almost every star in the sky has at least one planet around it. We may even find extraterrestrial life in our own solar system: Both Jupiter’s moon, Europa, and Saturn’s moon, Enceladus, have liquid water beneath their icy crusts, and on April 13, 2017, NASA announced that its Cassini Spacecraft discovered molecular hydrogen in water plumes emanating from Enceladus, indicating the presence of two key requirements for life—liquid water and a source of energy.
With all of these discoveries and with 1023 stars in the universe, it would seem statistically very likely that life exists in some of these alien solar systems. Indeed, in June of last year, The New York Times acknowledged this new perspective with an optimistic piece titled, “Yes, There Have Been Aliens.”
But not so fast. As Ross Andersen argued in a rebuttal to that New York Times article, these optimistic statistics and promising discoveries can’t tell us for sure that we aren’t alone. The only place we know life exists is here on Earth. And yes, on our planet it is tenacious—thriving 20,000 feet down, where strange organisms flourish on deep-sea vents without sunlight or oxygen, and 20,000 feet up, where cacti and insects have found a niche in the Atacama Desert. And yes, it is also resilient, adapting to ponds as corrosive as battery acid and feeding off radioactive waste in Chernobyl. And yet, we don’t know how life actually began here on Earth. Additionally, modern DNA analysis tells us that complex life, anything beyond a single cell organism, resulted from a random “event” in which two cells came together to form eukaryotes—something that apparently happened only once in the 4.5-billion-year history of our planet. Every worm on a deep sea vent, or cactus eking out an existence in the high Andes, every human who hunted on the plains or stood on the moon owes their existence to a single chance meeting of two cells that learned to get along.