Welcome to my blog, which I happen to be starting on the day after it was announced that Kepler, NASA’s planet hunting satellite, discovered an Earth-size planet around a star some 173 parsecs from Earth. The star hosting this monumental discovery is located between the constellations Cygnus and Lyra.
This planet is the second one discovered in the system, having a mass of about four and a half Earths and a radius approximately one and a half times that of the Earth. Though an amazing discovery, this Earth-size planet is most certainly not Earth-like. With a year that is shorter than a single day on Manhattan, the planet zips around its star in an orbit smaller than that of Mercury. The planet’s high density implies a rather large metallic core, and hosts a surface gravity more than twice that encountered in Central Park. No doubt New Yorkers would find the oppressive gravity and overwhelming heat on par with an evening spent in Hoboken, and if we find the conditions unbearable, then it is highly unlikely that any form of life has evolved on this remarkable find. For members of the numerati, specific data about the system has been released by NASA. The high probability that Kepler-10b cannot sustain life is supported by the fact that it lies outside the habitable zone of its parent Star.
The concept of a habitable zone is an interesting model used by Astronomers to describe the region where the necessary conditions for Life, as we know it to come into being and to persist, exist. The underlying idea behind it is that the complex chemical dance behind the cellular machinery of Life needs liquid water as its medium, hence to sustain Life, a planet must have this precious resource. If the planet gets too far away from its host star, the sunlight impacting on its surface won’t be enough to prevent water from freezing into the crystalline lattice we all know as ‘rocks’ in our well-aged whiskey. Inversely, too close a proximity will cause water to evaporate and turn into steam, puffing away the lakes, seas, and oceans to create a planet-sized sauna.
Though interesting as a toy model, the concept is still in its infancy, requiring quite a bit of refinement before astrobiologists can say for certain that they know where to look to find Life. Both atmospheric and geophysical conditions can drastically affect the temperature on a planet, causing liquid water to form even if its orbit lies outside of the habitable zone. A planet’s albedo (how much light the surface reflects), atmosphere (through greenhouse effects as explained to us by Al Gore), axial tilt (causing certain parts of the planet to receive sunlight for extended periods of time), and rotational speed (causing the planet to get dizzy) can all act to help increase surface temperatures by trapping heat. Geophysical effects can further heat things up, not just on planets, but in the moons that orbit them. Gravitational tidal forces generated by Jupiter heat the cores of Europa and Io like a sculptor’s hands kneading clay, causing the moons to have molten cores rather than leaving them simple, cold and inert spheres floating through the dark. Like gargantuan fortune cookies, there are no doubt vast treasures waiting underneath the crusts of these two active moons for future scientific exploration to uncover, even though their host planet is well outside the outer edge of the habitable zone of our solar system.
To further throw a wrench into a room full of Billyburg hipsters, the very premise that the chemical reactions of Life require liquid water as the stage upon which to act out their vibrant dance could be at fault. There are no reasons, a priori, why liquid methane cannot provide a similar enough environment for amino acids to form in. Along similar lines of reasoning, it was believed that the elements Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorous and Sulfur (easily recalled with the acronym CHNOPS thanks to my high school AP Biology teacher, Mr. Reid) were required for Life to exist. A controversial study done by NASA scientists in 2010 found evidence that this long cherished dogma could be wrong: apparently a certain species of bacteria found in Mono Lake, California, has replaced the Phosphorous in its biochemistry with Arsenic, a deadly poison!
Who can tell what other surprises scientists will find as they continue to study life on Earth? Undoubtedly our understanding of Life’s ability to endure the harshest of environments is far from complete, and as it grows in magnitude so too will we see the expansion of that green highlighting we have called the habitable zone. As Kepler continues to find Earth-size planets in our galactic neighborhood it is within the realm of possibility that its gaze will happen upon a place were the miraculous happenstance that occurred here on Earth four billion years ago was mirrored by the threads of fate, and perhaps, with remarkable synchronicity, the inhabitants of that sister-rock look out into the heavens as well, for clues that they are not alone.
Damn… all that waxing philosophic has made me hungry. I hope you’ve enjoyed this fun, fact-filled post, and I look forward to providing you with many more in the future. Now, what’s that number for Ollies…