Joana received a box from her brother containing several memory devices, some paper documents and a letter written a hundred and eighty years ago, at the turn of the XXI century. The arrival of an eclipse makes Joana the addressee of the letter. In this book, some of the documents are reproduced, an event that happened in 1905 is narrated and several events in a period of Joana's life in 2180 are recounted, describing her readings, thoughts and memories of things her brother told her. The story talks about computer science and physics, games and curiosities about the Moon, the travels of the Apollo missions and eclipses.

Antoni Amengual Colom is professor of Applied Physics at the University of the Balearic Islands and has published several books with Edicions UIB, including: Hablando de Física a la salida del cine(2005) and 30 temas de Física (2nd edition, 2010).