Harvard's top astronomer lays out his controversial theory that our solar system was recently visited by advanced alien technology from a distant star

From this book, the reader will gain an insight into one of the most creative minds in the history of space exploration. Krafft Ehricke's contribution to space

Experts critically examine the belief that other intelligent life exists in our galaxy.

Originally published in Great Britain by Profile Books Ltd, 2016.

Are alien civilizations really possible? If extraterrestrials exist, where are they? How likely is it that somewhere in the universe an Earth-like planet suppor