"In the Celestial World Open: Or, Speculations on the Inhabitants, Plants, and Products of the Planetary Worlds" is a unique book written by the famous Dutch scientist Christian Huygens. In this work, the author offers exciting hypotheses about what creatures, plants and other creatures may exist on the planets of our solar system. Thanks to an inquisitive approach and scientific validity, Huygens opens up incredible opportunities for the reader and deepens the understanding of outer space. This book will help everyone revise the usual ideas about life outside the Earth and ask new questions about the mysteries of the universe.