If you think we’ve done a great job with planet-finding so far, just wait until you learn what’s possible with microlensing!
When we think about finding planets in the Universe, we typically look for ways to detect them as they orbit their parents stars, either affecting their star’s position or velocity, or blocking or reflecting a certain portion of their light.
But what about the planets that are too small to be detected that way? What about the planets whose effects are imperceptible? And what about the rogue planets: the ones that no longer (or perhaps never did) orbit a star of their own?
Well, they’re not doomed to be invisible! In fact, we can measure and characterize them extremely well, through the power of gravitational microlensing. This isn’t some pipe dream of science fiction that may someday come to fruition; it’s real, current science that expects a tremendous explosion of planetary discoveries with WFIRST’s launch in the mid-2020s.