Astronomers have found thousands of exoplanets around single stars, but few around binary stars—even though both types of stars are equally common. Physicists can now explain the dearth.

Of the more than 4,500 stars known to have planets, one puzzling statistic stands out. Even though nearly all stars are expected to have planets and most stars form in pairs, planets that orbit both stars in a pair are rare.

Of the more than 6,000 extrasolar planets, or exoplanets, confirmed to date—most of them found by NASA’s Kepler Space Telescope and the Transiting Exoplanet Survey Satellite (TESS)—only 14 are observed to orbit binary stars. There should be hundreds. Where are all the planets with two suns, like Tatooine in Star Wars?