Moon Life

Author's Note: During the research for this essay, I read several articles from NASA, The Planetary Society and Space.com, among others. I've linked those articles for my reader to have a more in-depth look at the science behind my speculations. Enjoy.

The planet-killing cataclysm that rendered one quarter of our earth's mass into a space borne cloud of molten ash is inconceivable to us. Even those alive now who watched as Mt. St. Helens erupted, dashing hundreds of square miles of pine forest into kindling and sending pyroclastic clouds into the stratosphere would be unable to fathom the event that gave us our lone orbiting satellite. Such an occurrence, even done up in the grand cinematic style of movies that celebrate masochistic and catastrophic scenarios, is not something we can conjure in our most febrile dreams.

So why do we have a moon and where did it come from? Skipping over the mythological suppositions of our iron-age goat herding ancestors because we know what they believed, we can discuss at least two scientific theories worth considering. Early on in the discussion about our moon, it was widely held that a supermassive comet came hurtling out of deepest space, was knocked off course by an asteroid or other large object and then, zooming sunward, collided with our then somewhat larger home planet, cracking off a significant chunk which later solidified fairly rapidly into the moon. This is called the "capture theory" and it is at least mechanically feasible.  However, modern scientific research (including the Apollo trips to the moon to categorize the pumice on its surface) suggests something even more explosive occurred. It’s called “giant impact theory”. In this celestial melodrama, a smaller, Mars-sized planet on a dangerous orbital trajectory with our future home smashed into proto-Earth, filling the local neighborhood with chunks and splinters of both planets, but probably destroying the former almost completely.

What remains of this violent, literally earth-shattering event is our moon. That big white disc of floating spherical rock in the sky isn't just a moon, though. She is (ancients called her Luna or Diana, thus the female pronoun) almost a planet in her own right. She's nearly the size of Mars, our next neighbor proceeding outward in the Solar System and of a size with the largest of the other moons around us. The moon is completely devoid of life (except for remnants of our recent visits). She has no geological or volcanic activity. She has no subcutaneous water or signs of microbial history. She doesn't spin. She just floats there, providing a kind of mooring stability for Earth that is unique through the rest of our solar neighborhood. 

Other planets' moons cause gravitational disturbances that send their poles wobbling. This, in turn, encourages the weather on those planets (such as it is) to be unpredictable and malevolent. Some of the larger gas giants have many smaller moons, all of which provide incredible gravitational influence on their parent planets. Recently it was discovered that Jupiter had 12 more moons than originally believed. Not to be outdone, the Jovian gas giant's ringed brother planet, Saturn, proved to have 62 more moons.

I imagine the deeper gas giants as whirling monstrosities, gargantuan gods reveling in their own glory as they spin and swirl through our solar system. As they arc through space, they are pulled, pushed and pillaged by dozens of heavenly bodies caught in their orbit which torture their paths around our sun. Imagine trying to waltz with 62 children attached to you by ropes. Calamity will ensue.

By comparison, Earth is omni lunar. We deftly spin through the blackness of space, swaying not at all, our partner locked to us in a fittingly intimate gravitational embrace keeping us stable. As a result, we have tides, seasons, and even predictably dependent weather which allows for the rampant, glorious chaos of life in all sizes and all variations. Our moon may even be part of the reason why Earth rests in that ticklish realm of perfect temperance lovingly called The Goldilocks Zone because for life, it is “just right.” The ancient collision may have knocked us out of the infernally hot or desperately frigid zones occupied by Mercury and Venus respectively. True, our poles may be too cold and the equator too sultry, but nearly everywhere on the planet, including the teeming oceans, life can and does thrive. 

So far, life has eluded us elsewhere in the Solar System, or so we believe. We have found evidence on Mars of the possibility of life having existed at some point in the form of microbes in flowing water. It may be possible that life could thrive yet again, despite its current barren reality.

Our other solar siblings are either too hot (close to the sun), too cold (far from the sun) or are composed of atmospheres that, as part of their unknowable cyclopean qualities, would smash fragile space faring humanity like a steamroller hitting a fruit stand. In this deeply inhumane neighborhood of mind numbingly massive planets and vast distances, there is yet a small, albeit interesting possibility for life beyond earth: hundreds of moons. If there’s one thing our solar system does well it is to produce moons.

Recently, it has become a very pressing scientific goal to find earth-like planets that meet the nuanced criteria for supporting life. Not least among these doppelganger planets’ ideal traits is a watery, rocky terrain with a steady geological pulse. Lots of water and mountains, tectonic and volcanic activity, plus close enough to their own relative stars to create a habitat as similar to Earth’s as possible. The real problem with these particular ‘earth clones’ is that they are more distant than we could possibly even consider traveling to. We’re still daunted by the six-month commute to Mars. And yet, the distances around our own solar system are, while more manageable with the science we have now harnessed, slightly less inconceivable.

This is why scientists are also looking closely at some of the moons that have Jupiter and Saturn in raging competition. Three at least of those moons may be the kind of life-sustaining planet where humanity could survive and even thrive. Jupiter’s two elder children, Ganymede and Europa both have signs of icy surfaces, but they also seem to have oceanic water beneath the ice. Enceladus, Saturn’s moon (not his largest, but the only moon with its own rings), also seems to have oceans under the ice, as well as vast clouds of methane wafting from its icy surface.

Ganymede is the largest moon in our solar system, larger by a hair than the aptly-named Titan or the planet Mercury. Europa is on par with our own moon. Enceladus, though tiny, bears the stamp of life in the plumes of methane. A common byproduct of digesting plants, this world creates gobs of the gas, a nod to its possibly life-friendly manner. Except that they orbit their gas giant parents, they might very well be considered planets rather than moons in their own right, both because of their spherical shape and because of their comparative sizes to the inner planets. It is feasible that they were once planets that were drawn into the orbits of the gas giants and away from their original planetary circuits.

Powerful infrared telescopy which helps scientists to view the aurora on Jupiter’s moons caused by the Jovian magnetic field, allows discernable spectral analysis which suggests that there is water under the icy surfaces of two of the three moons. The warmth of Jupiter and the gravitational forces produced by the other moons in the area may be enough to keep those watery depths from freezing, which could mean that the intrusion of the seminal proteins and amino acids that conceived life on Earth may also have penetrated the ice on Ganymede and Europa while riding on asteroids or on bits of fractured comets. 

Is there any chance that those water-bound beings will have discovered their place in the solar system or that their science will have developed a means of traveling toward the local star, passing Earth and our lonely, barren moon as they swing by? No one really knows. 

Nevertheless, for right now, as those other worlds teeter and roll, keeping their powerful secrets, our moon keeps us balanced just enough so that we can continue to evolve our ability to look up and wonder about what’s really out there. Soon enough, if we keep on at the pace we are burning ourselves out of a homeworld, we may find that those icy moon seas are a home for us until we can break the barriers of time and space and colonize an earth-like planet in another system. I just hope that wherever that earth-like planet is, it has a life preserving moon.