New Planet-Hunting Technique Finds Worlds We Can See Directly

When astronomers discovered the first worlds orbiting other stars thirty years ago, they also began taking what might be called the galactic planetary census, tallying up the numbers and types of exoplanets in the Milky Way. Although it’s infeasible to thoroughly survey all of our galaxy’s hundreds of billions of stars, a representative sample of them could offer important information. By studying the planetary populations of such a sample, researchers hope to learn which sorts of worlds are most common or rare—and how our own Earth and solar system measure up against them.

But there are several different ways to find planets, and each tends to work best for different types of worlds, leading to potentially skewed results. The dominant techniques to date infer a planet’s presence by looking for its subtle influence on its star, and they are most sensitive to giant planets very close to their stars. Such worlds have orbital “years” as small as a few days or weeks—and none exist in the solar system. In contrast, viewing planets directly—called direct…