Astronomers just found the closest black hole to Earth
With enough magnification, many stars might look like this system, with one or more stars orbiting an otherwise invisible black hole. (ESO/L. Calçada/)The crisp points of light that fill the night sky often play tricks on the naked eye. Take Sirius, our brightest star (after the sun). When magnified with a mighty enough telescope it splits into two stellar partners—Sirius A and Sirius B. Other systems come in threes, fours, or more. Much as planets orbit stars to craft solar systems, stars conspire with one another to form systems of their own.Keen-eyed star gazers in the southern hemisphere might barely be able to spot one such system in the constellation Telescopium. While the otherwise inconsequential pinprick doesn’t look like much to the naked eye, past analyses of its flickering light have discerned a double star. Now, follow-up observations have found traces of a third companion hiding in the dark. Weighing...