Back in Time is an education book app for iOS about the history of the universe, earth, life and mankind that uses a time analogy to explain different timescales. Released on September 22, 2011, it was developed by the software company Landka in collaboration with scientific institutions such as ESA/Hubble Space Telescope. The app was featured worldwide in the App Store and rapidly became a success, reaching the top sales of iPad book apps in 38 countries. Back in Time was distinguished by The New York Times and selected for the top 10 apps of the year. In 2012 it was recognized with a World Summit Award (UN based initiative). Features Back in Time is a cross between a history textbook and a multimedia encyclopedia. The app presents 50 key events since the beginning of the universe until the present day covering different timescales such as the chronology of the universe, the geological history of earth, the evolutionary history of life and human history. In order to better understand these timescales, the app proposes a time analogy where the entire age of the universe (13.7 billion years) is scaled into a 24-hour clock. Navigation is possible by browsing several timelines or by rewinding the pointers of a clock to go back in time. The text of each chapter is complemented with images, videos, interactive timelines, animations and trivia. The app's soundtrack was produced by Rodrigo Leão. Time analogy Back in Time presents the most relevant events in history using a 24-hour clock as a time analogy. This analogy scales the entire age of the universe (13.7 billion years) into a single day (24 hours) so that the beginning of the universe (Big Bang) started at 0:00h and at present time the imaginary clock reads 24:00h. Back in Time uses this analogy as a method to visualize and compare key events in the history of the universe, of earth, life, and human history. This analogy was originally proposed by Astronomer Bob Lambert from the John J. McCarthy Observatory as a tool for helping students visualizing large timescales. * milliseconds before midnight Development and release Back in Time was developed by the Portuguese software company Landka over a period of 10 months. The iPad version was released on the App Store on September 22, 2011. The initial version included 44 chapters and was available in 5 languages (English, Spanish, German, French and