Free Astronomy Magazine November-December 2019

EXOPLANETS 5 he paradox NOVEMBER-DECEMBER 2019 A t night, under a streetlamp, there is a drunk who is looking for some- thing. A policeman approaches and asks him what he has lost. “I lost my house keys,” the man replies, and they both start looking for them. After looking for a long time, the policeman asks the drunk if he is really sure he lost the keys there, and he is told: “No, I think I lost them in the park.” “But then, why are you looking for them here?” “Because there is more light here!” This bizarre tale, taken up and adapted by various twentieth-century authors from a satirical tale of the thirteenth century, is today known as the “streetlamp” paradox. It is a type of observational distortion that consists of looking for something where it seems easier to find, even if if the re- searcher knows in advance that he will not find what he is looking for. At the very least from his efforts, he will show that it is not there. Astronomers looking for habitable exo- planets are today in the position of the A n imagined representa- tion of planet K2- 18 b, its star and the planet that accompanies them in the sys- tem. [ESA/Hubble, M. Kornmesser]