Grain-sized remnants of alien technology may get caught in solar wind and land on plants and moons close to us ...

Billions of years ago, while the solar system was still young, a massive object may have drifted into it. It's not a spaceship, but it is an alien visitor in its own right—a colossal ...

Even at this early stage in our spacefaring age, humanity has already begun sending probes that will eventually reach other ...

Is the rest of the cosmos a pristine environment awaiting the arrival of humanity’s “post-human” descendants? Or is advanced ...