Planets with two suns are mysteriously scarce, and scientists now think Einstein’s relativity is to blame. Credit: AI/ScienceDaily.com Out of more than 4,500 known planet-hosting stars, one surprising pattern stands out. While planets are expected to form around most stars and many stars exist in pairs, worlds that orbit both stars are unusually uncommon. Among the more than 6,000 confirmed extrasolar planets, or exoplanets, discovered so far -- most by NASA's Kepler Space Telescope and the