In these science fiction books, extraterrestrial beings are sympathetic, horrifying and everything in between.

For over six decades, the Search for Extraterrestrial Intelligence (SETI) has been tirelessly scanning the cosmos for signs of alien life. Despite its extensive efforts, the universe remains eerily ...

(cokada/iStock/Getty Images) Alien megastructures built to harvest stellar energy or alter the orbits of stars may be ...

Trump has ordered a UFO data release. But if aliens exist, what would they think of us? - For generations, human beings have ...

The third known visitor from another star system, Comet 3I/ATLAS, has been racing through the Solar System with just enough weirdness to ignite a familiar debate: is it natural or could it be ...

Comet 41P/Tuttle-Giacobini-Kresak has begun acting a little unusually, but there are likely natural explanations before we go ...

Over hundreds of thousands of years, humans somehow evolved a type of intelligence found nowhere else in the animal kingdom, at least on Earth. According to the most famous theory describing the ...

Movies like "Disclosure Day" and "Project Hail Mary" renew our fascination with extraterrestrials and the idea that humankind ...