V neob'yatnom more yarkih tochek, useivayuschih zvezdnoe nebo, est' svetila, kotorye v milliony raz blizhe k nam i imeyut sovershenno inuyu prirodu, nezheli vse ostal'nye zvezdy. Zagadochnaya osobennost' etih zvezd zamechena byla uzhe v glubokoj drevnosti. Chelovechestvo davno vydelilo ih iz tysyach drugih, prisvoiv im obschee naimenovanie "planet," t. e. (po-grecheski) "stranstvuyuschih" ili "bluzhdayuschih" svetil. Oni takie zhe miry, kak i obitaemyj nami zemnoj shar, tol'ko rassmatrivaemye s ogromnogo rasstoyaniya v teleskop. Ob etih nebesnyh sestrah nashej Zemli i budet idti rech' v etoj knige.
Yakov Isidorovich Perelman (Russian: Яков Исидорович Перельман; December 4, 1882 – March 16, 1942) was a Russian and Soviet science writer and author of many popular science books, including Physics Can Be Fun and Mathematics Can Be Fun (both translated from Russian into English).