Miguel A.F. Sanjuán is full professor of Physics at the Universidad Rey Juan Carlos in Madrid, Spain, where he is the Director of the Research Group in Nonlinear Dynamics, Chaos and Complex Systems. He has been a Visiting Research Professor at the University of Tokyo, funded by the Japan Society for the Promotion of Science; a Fulbright Visiting Research Scholar at the Institute for Physical Science and Technology of the University of Maryland at College Park, Visiting Research Professor at Beijing Jiaotong University, and Visiting Professor at the Kaunas Technological University. He is Honorary Professor of Sichuan University of Science and Technology (Zigong, China), and Honorary Professor of Huaqiao University (Xiamen, China). He also serves as the Editor General of the Spanish Royal Physics Society. He is a Corresponding Member of the Spanish Royal Academy of Sciences, a Foreign Member of the Lithuanian Academy of Sciences, and a regular member of the Academia Europaea. He has published the monograph Nonlinear Resonances (Springer, 2015). Juan C. Vallejo is an astrophysicist in the Nonlinear Dynamics, Chaos and Complex Systems Research Group at the University Rey Juan Carlos since 1999. His research has focused on analyzing the impact of chaotic dynamics in computer simulations for astronomy. He worked for twenty years at the European Space Astronomy Centre in Madrid, and is also working in the Joint Center of Ultraviolet Astronomy at the Universidad Complutense of Madrid.

• Preface.- Forecasting and chaos.- Lyapunov exponents.- Dynamical regimes and timescales.- Predictability.- Chaos, predictability and astronomy.- A detailed example: galactic dynamics.- Appendix.

Miguel A.F. Sanjuán is full professor of Physics at the Universidad Rey Juan Carlos in Madrid, Spain, where he is the Director of the Research Group in Nonlinear Dynamics, Chaos and Complex Systems. He has been a Visiting Research Professor at the University of Tokyo, funded by the Japan Society for the Promotion of Science; a Fulbright Visiting Research Scholar at the Institute for Physical Science and Technology of the University of Maryland at College Park, Visiting Research Professor at Beijing Jiaotong University, and Visiting Professor at the Kaunas Technological University. He is Honorary Professor of Sichuan University of Science and Technology (Zigong, China), and Honorary Professor of Huaqiao University (Xiamen, China). He also serves as the Editor General of the Spanish Royal Physics Society. He is a Corresponding Member of the Spanish Royal Academy of Sciences, a Foreign Member of the Lithuanian Academy of Sciences, and a regular member of the Academia Europaea. He has published the monograph Nonlinear Resonances (Springer, 2015). Juan C. Vallejo is an astrophysicist in the Nonlinear Dynamics, Chaos and Complex Systems Research Group at the University Rey Juan Carlos since 1999. His research has focused on analyzing the impact of chaotic dynamics in computer simulations for astronomy. He worked for twenty years at the European Space Astronomy Centre in Madrid, and is also working in the Joint Center of Ultraviolet Astronomy at the Universidad Complutense of Madrid.

• Preface.- Forecasting and chaos.- Lyapunov exponents.- Dynamical regimes and timescales.- Predictability.- Chaos, predictability and astronomy.- A detailed example: galactic dynamics.- Appendix.

Miguel A.F. Sanjuán is full professor of Physics at the Universidad Rey Juan Carlos in Madrid, Spain, where he is the Director of the Research Group in Nonlinear Dynamics, Chaos and Complex Systems. He has been a Visiting Research Professor at the University of Tokyo, funded by the Japan Society for the Promotion of Science; a Fulbright Visiting Research Scholar at the Institute for Physical Science and Technology of the University of Maryland at College Park, Visiting Research Professor at Beijing Jiaotong University, and Visiting Professor at the Kaunas Technological University. He is Honorary Professor of Sichuan University of Science and Technology (Zigong, China), and Honorary Professor of Huaqiao University (Xiamen, China). He also serves as the Editor General of the Spanish Royal Physics Society. He is a Corresponding Member of the Spanish Royal Academy of Sciences, a Foreign Member of the Lithuanian Academy of Sciences, and a regular member of the Academia Europaea. He has published the monograph Nonlinear Resonances (Springer, 2015). Juan C. Vallejo is an astrophysicist in the Nonlinear Dynamics, Chaos and Complex Systems Research Group at the University Rey Juan Carlos since 1999. His research has focused on analyzing the impact of chaotic dynamics in computer simulations for astronomy. He worked for twenty years at the European Space Astronomy Centre in Madrid, and is also working in the Joint Center of Ultraviolet Astronomy at the Universidad Complutense of Madrid.

• Preface.- Forecasting and chaos.- Lyapunov exponents.- Dynamical regimes and timescales.- Predictability.- Chaos, predictability and astronomy.- A detailed example: galactic dynamics.- Appendix.