In 2017, scientists at a Hawaiian observatory glimpsed an object soaring through our solar system, moving so quickly that it could only have come from another star. Avi Loeb, Harvard's top astronomer, showed that it was not an asteroid; it moved along a strange, orbit and left no trail of gas or debris in its wake. There was only one conceivable explanation: the object was a piece of technology created by a distant alien civilization. Now with a new afterword by the author, Extraterrestrial reveals the thrilling story of the first interstellar visitor spotted in our solar system, outlining a controversial theory with profound implications for science, religion, and the future of our species. Book jacket.