Mirror Earth


Are you curious about why the NASA space observatory whose mission is to search out other worlds should be named after seventeenth-century astronomer Johannes Kepler? True, he was a seminal genius in the star-gazing biz, but so are many others who could have legitimately contributed their moniker. But Kepler had one extra arrow in his quiver. He was arguably history’s first hardcore science fiction writer, at least in the eyes of such experts as Carl Sagan and Isaac Asimov. His novel Somnium stands pretty much alone as first to speculate realistically about life on other planets. Literature adds that dash of glory and public acclaim to science every time!

Before Kepler, other planets and their putative inhabitants were seen merely as extensions of terra firma, like exotic China or India. “There is little in most…pre-twentieth-century accounts to distinguish other worlds from the strange Earthly lands featured in many travelers’ tales and romances,” notes critic Brian Stableford at the Science Fiction Encyclopedia. But once other worlds were conceptualized as equal in status, yet truly alien and distant, they could then enter the realm of proper scientific research. And so to Kepler goes the credit for launching the field of exoplanetary science.

As Mirror Earth, Michael D. Lemonick’s engrossing new account of this relatively young field, reveals — in a swift, thrilling narrative, replete with passionate characters, suspense, politics, setbacks, and triumphs — exoplanetary science languished as a kind of pencil and paper speculative game until the right technology and the right visionary inspirations coincided. After that, the riches began to rain down from the heavens. Now we stand poised on the threshold of the ultimate coup: finding a “mirror Earth,” or twin to our hospitable home.

Lemonick’s schema is to convey to the reader both the Dark Ages and the new Golden Age of exoplanetary research, and he does so with panache and deep understanding. He starts with instant immersion, by reporting on some fairly recent exciting discoveries centering around the Kepler telescope. Then he backtracks all the way to the Classical era, when ancient Greeks were just beginning to theorize about the “plurality of worlds.” After that backstory, we return to the recent twentieth century, when competing and cooperating teams of scientists began to codify the techniques for affirming the existence of other planets outside our solar system, incredible lightyears away. With utmost clarity, employing plenty of vivid metaphors, Lemonick details the two major techniques of planet discovery: radial-velocity searches (how a planet perturbs the motion of its star) and transit searches (how a planet can be spotted as it crosses the face of its star). A third method, gravitational lensing, is less potent, but still useful, and gets its focus as well.

The Kepler instrument employs the transit technique, and is the star of this saga. Launched only in 2009, it has since revealed over a thousand candidates for planethood. Its creation was not without arduous battles by hundreds of committed, true-believer scientists, and Lemonick’s generous portraits of these men and women — the “exoplaneteers” — are full of empathy, affection, and respect. He conjures up the love they have for the wonders of the cosmos — as well as their normal human quirks and failings — with brush strokes both minute and broad, as necessary. Note, for example, Chapter 11’s sensitive and respectful depiction of a “horrible breakup, like the worst divorce” that happened amongst several researchers.

One of the big revelations that Lemonick delivers is how surprising the universe remains. Scientific expectations were undermined and reversed throughout this quest, and entire new unsuspected categories of objects emerged. I am particularly fond myself of the notion of a planet featuring “a core of pure diamond, with diamond continents sloping down to seas of tar.”

As the book’s title suggests, much of the excitement in the field revolves around finding a world with the parameters of Earth, hence a possible refuge for living organisms, and Lemonick traces their bloodhound-like pursuit of the prize in many exciting stages. The pioneers involved in exoplanetary research are not just collecting Big Blue Marbles, but are intent on establishing humanity’s role in the universe: freakish singleton, or member of a galactic community.

The Speculator

Paul Di Filippo’s column The Speculator appears monthly in the Barnes & Noble Review.  He is the author of several acclaimed novels and story collections, including Fractal Paisleys, Little Doors, Neutrino Drag, and Fuzzy Dice.

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