So many questions have been asked this year—questions about governments, pollsters, news media, celebrities, conspiracy theorists, star athletes, and politicians. Questions about the future of our country, our freedoms, our rights as citizens in the United States—the rights of our neighbors, our friends, our families…
The noise is everywhere and nowhere at once; it’s impossible to tune out and yet nearly as impossible to remain tuned in, up to date, alert about the latest malfeasance from some entity or another. These are the times that try our spirit and make us yearn for the simpler questions. For example: are we alone in the universe?
Okay, so that’s not exactly a simple question—scientists have been wondering and working on it for generations, searching for empirical evidence of extraterrestrial life forms, or, at the very least, celestial bodies that might be able to support it.
That’s precisely the motivation behind Kepler, NASA’s mission to examine our galaxy in search for other worlds. The project itself is massive—launched in March 2009, the spacecraft and mission cost $550 million. It was initially slated for just three years of orbit before being extended in 2012, and it certainly hasn’t been a waste. Back in May, NASA announced that the Kepler mission had discovered 1,284 new planets—the largest collection of planets ever discovered—more than doubling the amount previously discovered by Kepler and bringing the total number of exoplanets discovered since 1988 to 3,545 (as of this writing).
Those staggering totals include 2,660 planetary systems and 597 multiple planet systems, but even among those huge clusters, not all can handle life as we know it (which essentially means liquid water). Aside from being rocky, the exoplanets must exist within the circumstellar habitable zone, or “the annulus around a star where a rocky planet with a carbon dioxide-water-nitrogen atmosphere and sufficiently large water content (such as on Earth) can host liquid water on its solid surface.”
The circumstellar habitable zone, better known as the “Goldilocks Zone” (because things are juuust right—get it?) is a tall order to fill, but there remains the possibility that other solar systems are more densely packed than our own. The general consensus is that five rocky earth-like planets can safely exist within a given star’s habitable zone, but that depends on both star and planet size.
“The Kepler mission has shown us that very tightly packed systems exist, but they don’t quite reach the level of packing required to stuff five Earths in the habitable zone,” Christina Van Laerhoven, planetary scientist at the Canadian Institute for Theoretical Astrophysics in Toronto, said in a space.com article. “That said, finding small planets is challenging and I don’t think we’ve yet seen all the kinds of planetary systems that nature can create.”
That quote leaves open endless possibilities for solar system and planetary formation in the universe, let alone life in those systems. It’s entirely possible for organisms to exist on planets that don’t fit our standards for life—perhaps there are forms of life based on compounds humanity has yet to discover or even has the capability of comprehending.
But given this hypothetical infinity, this endless array of potential, another, more fundamental question still begs: why? Why bother searching for planets similar to Earth in size, makeup, distance from its star, especially when so many of them are so painstakingly far away?
The answer to that question is the answer to why the study of science exists at all—the quest for knowledge, the journey to understand forces that are outside of our control, and in this case, far greater than the sum of our collective parts. Until that planet exists, an exact mirror or replica or even cousin of Earth, we are, for all intents and purposes, alone in the vast chasm of the universe. It’s human nature to continue pushing outward, to aim for discovery.
In his book “A Brief History of Time,” famed theoretical physicist Stephen Hawking wrote that “the boundary condition of the universe is that it has no boundary.” Space is about as endless as we can imagine, and the Kepler mission is confined to only one section of our galaxy. Optimistic though the sentiment may be, earth-like planets could well exist far beyond the vast reaches of the Kepler spacecraft’s scope. Those may yet be unreachable, but given the unknown, untapped swaths of space, how on Earth could we stop now?
As the holidays roll around and the new year draws closer, the questions and conflicts surrounding our human systems will only grow louder. People will shout and clamor over what they think is right for all of us, while those they argue against will attempt to match their volume.
With all the uncertainty therein, it might come as comfort to remember there are bigger questions—literally—always being asked and trying to be answered about the skies above us and the possible worlds beyond our own.