New Technique May Help Find Galaxy's 100 Billion Earth-Like Planets

Artist's illustration of how common planets are around stars in the Milky Way. The planets, their orbits, and their host stars are all vastly magnified compared to their real separations. Credit: ESO/M. Kornmesser Finding Earth-like planets is hard. For years, astronomers searching for worlds beyond our solar system found mostly gas giants like Jupiter, since those are bigger and easier to detect, even though smaller planets might actually be more common. But a paper in the Monthly Notices of the Royal Astronomical Society suggests a new way of looking for exoplanets may help find the estimated 100 billion Earth-like planets in the Milky Way. The new technique, which is actually just an improvement on an old technique, relies on an unusual quirk of nature. A heavy object warps the space-time around it, distorting the nearby universe. Sometimes this effect, called gravitational lensing, leads to a distant galaxy’s light “smearing” around a closer one, and sometimes even creating unique shapes. It turns out, though, that even planets can warp their stars’ light enough for scientists to notice — a phenomenon called microlensing. In the past, researchers could only detect the effect from larger gas and ice giants, but the new research spells out a way to increase the sensitivity enough to find the smaller Earth-like worlds. Actually putting this technique to work and finding the planets (and then determining which have Earth-like conditions suitable for extraterrestrial or human life) is still a ways off. Astronomers would need a worldwide network of robotic telescopes to more easily spot Earth-sized microlensing. Luckily, they should have just such a network within a few years, as the Las Cumbres Observatory Global Telescope Network becomes operational and can work together with NASA’s Kepler space telescope and other ground-based scopes. As these instruments and our understanding of the universe improve, it’ll only get easier to find Earth-like worlds. If there really are something like 100 billion of them out there, the odds are pretty good we’ll also find some with habitable conditions... and then who knows what else we could find.