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 ...

Stellar plasma can smear alien radio signals before they escape their star system, making them harder for astronomers to detect.

NASA's alien-hunting Europa Clipper spacecraft took seven hours of ultraviolet observations of interstellar comet 3I/ATLAS while both objects zoom toward Jupiter. When you purchase through links on ...

There’s no denying the allure of alien artifacts. Science fiction is awash in the material remnants of extraterrestrial civilizations, which surface in everything from the classic books of Arthur C.