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Quick, how many planets are in the solar system? Sidestepping the contentious issue of Pluto’s planethood, it’s safe to say you probably answered that less than ten planets orbit our Sun.
Now, how many planets are known outside the solar system? Twelve? Forty-two? A hundred? You’d be forgiven for not knowing the answer, because it changes all the time. And, to be fair, the tally has no immediately obvious implications for anyone’s daily life. At present, astronomers have confirmed the existence of about 460 extrasolar planets, or exoplanets. If that surprises you, this will too: That figure is set to double in less than a year.
The primary reason for this incoming deluge of alien worlds is a single NASA spacecraft, Kepler, which is looking for exoplanets around 156,000 stars within a 100-square-degree swath of the sky. Kepler only can find a small percentage of the exoplanets that exist around those stars; it’s only sensitive to transiting exoplanets, worlds aligned by chance so that in their revolutions around their stars they cast a shadow toward the vigilant spacecraft. For perspective, detecting an Earth-sized transiting exoplanet around a Sun-like star across an expanse of hundreds or thousands of light-years is not that different from spotting a single burnt-out pixel on your computer monitor from several kilometers away. That Kepler’s search method works at all sometimes seems too good to be true.
But it does work, nearly flawlessly. On Tuesday, the Kepler team announced that in only the first 43 days of the 3.5-year-mission, the spacecraft had already found more than 700 yet-to-be-confirmed planetary “candidates.” Of these, several will undoubtedly be false positives, but the bulk will likely prove to be actual worlds.
Some of the candidates are Earth-sized, and may even be Earth-like—unlike the vast majority of previously known exoplanets, which are bloated orbs of gas more akin to Jupiter or Neptune. The newly released data conclusively supports a long-standing hypothesis among astronomers that small planets are much more abundant than large ones. It also suggests that the architecture of our own solar system, where planets occupy the same plane in roughly circular orbits around the Sun, may be more common than once supposed. Put more simply, the data implies that the foundational conditions for life as we know it—small rocky planets in tranquil and temperate orbits around their stars—are quite prevalent in our galaxy.
Given that the new batch of candidates only represents a small portion of Kepler’s total observation time, it stands to reason that by the mission’s end it will have cataloged thousands of exoplanets, and perhaps hundreds of Earth-sized worlds, some of which, just maybe, could harbor life intelligent and otherwise. This data release is just a preview of much grander things to come.
Bizarrely, these newsworthy and historic revelations weren’t the main focus of most news coverage of the Kepler data this week. Instead, many media outlets paid more attention to the fact that the Kepler team only released data for just over 300 candidates—the additional 400 won’t be publicized until next February. The 300-odd candidates now known are all relatively humdrum finds; almost all the more tantalizing and revolutionary discoveries remain, for now, out of the public eye.
In response, some advocates of “open science” and more than a few planet-hunting astronomers unaffiliated with the Kepler mission have cried foul; typically, a taxpayer-funded NASA mission like Kepler would publicly release the entirety of its available scientific data after a year of proprietary usage. The spacecraft will likely produce enough data and enough planetary candidates to occupy a small army of researchers for years on end—surely the Kepler team should welcome all the help they can get!
Other than the obvious incentive of laying claim to discoveries generated by a project many of them have spent decades developing, Kepler’s scientists have more technical justifications for presently withholding the data: Verifying the mission’s most exciting finds is a painstaking and difficult process that usually requires gobs of observing time on the world’s largest ground-based telescopes, not to mention years of professional training and experience. Announcing the discovery of the first Earth-like planets beyond our solar system is something best handled with care, and the people least likely to make mistakes and “cry wolf” are those who are already intimately familiar with the machinery and the data. Allowing the Kepler team more privileged access for the time being seems justified.
I would guess that the real driving force behind the clamor over the Kepler data is the nature of the modern scientific career, in which researchers vie for shrinking pools of jobs and funding by trying to distinguish themselves from their peers in a meaningful way. Too often, that means scoring fractionally higher on a vast and muddy milieu of quantitative performance metrics made possible by the ongoing digitization of research.
The methods now available for slicing and dicing a scientist’s worth are seemingly endless. Yet, as detailed in a thoughtful series of articles in this week’s Nature, it’s unclear whether these metrics accurately measure the qualities that have historically proved so valuable to science: imagination, perceptivity, and persistence. “Scientometrics” is still a field where data proliferates at knowledge’s expense, and where the more artful sides of science tend to slip through the cracks. It’s worth asking whether a brilliant loner like Albert Einstein, an eccentric polymath like Isaac Newton, or a rebellious iconoclast like Richard Feynman would flourish or flounder beneath the weight of modern algorithmic scrutiny.
By contrast, being among the first to find celestial twins of Earth effectively sweeps all that clutter aside, and as far as planets are concerned the galaxy remains rich and undiscovered country. At present and for the next several years at least, there are abnormally few limits on the good science—and public outreach—that can be done. Such circumstances are rare in the average researcher’s lifetime.
Each and every author of the paper first formalizing an Earth-like planet’s discovery is all but guaranteed sky-high ratings in a host of performance metrics. This might not put them all in the history books, but it certainly would go a long way toward ensuring a lucrative reputation and steady employment in a pervasive atmosphere of shrinking budgets and limited opportunities. Which is why this era of astronomy may be remembered more as a planetary “gold rush” fueled by cutthroat competition rather than as a noble and honorable quest for cosmic meaning. Sordid and unfair though it might be, it’s hard to protest if the end result is still a comprehensive census of other living worlds.
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