Two pioneers of space exploration, Robert Esnault-Pelterie and Ary Sternfeld, introduced the words 'astronautics' and 'cosmonautics, ' respectively, into the scientific language. The origin of the term 'astronautics' is well documented. In contrast, the history of the word 'cosmonautics' remains poorly known. Ary Sternfeld is also largely forgotten. The fiftieth anniversary of the breakthrough to space, celebrated in 2007, makes it especially appropriate to remember those visionaries who paved the way to cosmos. The book tells the stories of 'astronautics' and 'cosmonautics' and describes a most unusual life journey of Ary Sternfeld