February 18, 2014
Imagine someone spent months researching new cities to call home using low-resolution images of unidentified skylines. The pictures were taken from several miles away with a camera intended for portraits, and at sunset. From these fuzzy snapshots, that person claims to know the city’s air quality, the appearance of its buildings, and how often it rains.
This technique is similar to how scientists often characterize the atmosphere—including the presence of water and oxygen—of planets outside of Earth’s solar system, known as exoplanets, according to a review of exoplanet research published in the Proceedings of the National Academy of Sciences. A planet’s atmosphere is the gateway to its identity, including how it was formed, how it developed and whether it can sustain life, stated Adam Burrows, author of the review and a Princeton University professor of astrophysical sciences. But the dominant methods for studying exoplanet atmospheres are not intended for objects as distant, dim and complex as planets trillions of miles from Earth, Burrows said. They were instead designed to study much closer or brighter objects, such as planets in Earth’s solar system and stars.
Nonetheless, scientific reports and the popular media brim with excited depictions of Earth-like planets ripe for hosting life and other conclusions that are based on vague and incomplete data, Burrows wrote in the first in a planned series of essays that examine the current and future study of exoplanets. Despite many trumpeted results, few “hard facts” about exoplanet atmospheres have been collected since the first planet was detected in 1992, and most of these data are of “marginal utility.”