In this book, Philip Plait — an American astronomer and popular science writer — takes readers on a journey through the cosmos in his spaceship. From lunar regoliths to the event horizon of a black hole, via Saturn’s rings and the Orion Nebula, Under Alien Skies is a book that lives up to its name. The 10 chapters that make up the book follow each other like the different stages of a journey, taking the reader further and further away — both in space and time — to discover landscapes that are sometimes breathtaking, sometimes disturbing, but always intriguing. In spite of everything, Under Alien Skies remains a work of popular science: Philip Plait ensures, thanks to his pen and his abundant imagination, that his readers not only contemplate, but also understand the workings of the Universe in which they live.
In the collective imagination, a space tourist leaps onto the ground of a distant planet, wearing his space suit. In this vision we find two of the major constraints associated with a pedestrian excursion to an alien world, largely dealt with in the first five chapters dedicated to our solar system.
The first constraint is gravity. Since the hum
