Vida extraterrestre : ¿Estamos solos en el universo o acompañados?

If it is estimated that there are between one hundred and four hundred billion stars in the Milky Way alone, just imagine the number of planets and moons. There are trillions of worlds out there! It seems logical to think that some of them might be inhabited, doesn't it? The truth is, we have no idea. What we *do* know is everything we’ll explain in this book about extraterrestrial life. What conditions must a planet meet to harbor life? Which are the best candidates we’ve found? Is there life on Mars? If aliens existed, what would they look like? Could we communicate with them? Have space expeditions been launched to find them? Suit up as an astronaut and get ready to explore the farthest reaches of the universe.