Guest Post: Exoplanets and the Scientific Possibility of Alien Life
A guest post from Aurora Vesper:
I always get excited when I hear about a new discovery of an exoplanet and its possibilities in the news or through the grapevine. As someone long captivated by scientific explanations and discoveries that push the boundaries of our knowledge and our ability to picture the world, such news always manages to hit my smile button. It calls forth a glint of the wonder of a small child first receiving an answer to “What are the stars?” shining through the years of context and identity foreign to the raw mind in which it first was born.
Something so recently confirmed—the existence of extrasolar planets at all—stirs such visceral excitement concerning our journey to knowing, and expanding even our possibility of discovery in this vast universe. Not long ago were planets orbiting stars other than our sun simply a likely conjecture, as life possibly blooming across them is now. In fact, “[t]he first published discovery [of an extrasolar planet] to receive subsequent confirmation was made in 1988."
I remember catching clips of Carl Sagan's Cosmos, what seems like a very long time ago, in which he drew out the Drake equation for viewers. Many of the variables in that calculation still remain a mystery, but in '78 and '79 when Cosmos was produced, we did not even have confirmation that its second variable—the fraction of stars that have planets—was naught but our “exceptional” (as some would have us believe) sun. Today, we do. And our evidence for planets being common, mundane even—like the chemicals of life themselves—in our universe continues to mount. How thrilling.
So what are our prospects? So far, we have found 706 confirmed exoplanets . Of course, at this point the number and type of evidence we have found is limited by our detection methods and does not speak definitively on the probability of extraterrestrial life. Far from it, in fact, compare what we would need to know and what we can know with our current detection methods and how little evidence we do have becomes painfully and awesomely obvious: and perhaps all the more precious for it. But at this key juncture, watching the cosmic drama play out is irresistible. In spite of all that, intelligent speculation and juicy hints from key pieces of evidence can give us a taste of the possibilities.
Long before we had our first confirmed exoplanet, there was speculation on the likelihood of life on other planets in the science and philosophy communities, dating back to the 16th century . Since then, science fiction has dealt with the topic incessantly, and scientists have honed their speculation in ever more specific ways. Here, Carl Sagan lays out the Drake equation, which deals with intelligent life, far better than text would allow. The field of exobiology has also emerged, dealing not just with the probability of intelligent life, but life in general, in any manifestation, with any possibility—whatever life might look like evolving on a planet different from our own.
Specific extrasolar planets present their own, more imminent yet more undefined curiosities. A few have emerged with headlines proclaiming ways in which they may be similar to Earth, and thus their possibility for containing life. HD 85512 b and Gliese 581 d are currently considered to have the most potential to contain life . Both are classified as “super-Earths” at 3.6 and 5.6 times Earth’s mass, respectively  . HD 85512 b is the smallest exoplanets in the habitable zone the scientific community has yet identified, as the current methods favor larger planets. As our methods for detection and amount of data continue to advance, we'll no doubt see even more exciting clues and revelations. And this is one of the many reasons why it pains me so much to see science programs across the board, including the space program, defunded.
While writing this post I was inspired to once again look up melodysheep's Symphony of Science, and though it's a few months old, I ran across his “Onward to the Edge” installment for the first time. I can't imagine a better thing to close out this post:
 "Researchers find potentially habitable planet" (In French)
Aurora Vesper was raised on religious tracts pretending to be textbooks and her skepticism resulted naturally from the facepalm following the completely sincere assertion that evolution was just a theory in class. Thank Teapot for the saving sips of the Unholy Internet. She has an odd desire to learn absolutely everything: a quest in which some standard for distinguishing fact and fiction proves to be helpful. She has a passion for pondering of all sorts, good coffee, generally unpopular vegetables, and heretical smirks. She wishes to use some or all of these inclinations to make the world a better place.
Featured image credit: NASA