TRAPPIST-1: Alien planet could be an “Earthlike water world” with lots of oxygen
The seven exoplanets that make up the system are all rocky, Earth-sized planets
Arecibo Message: How researchers sent the first interstellar radio message and why they did it (video-photos)
Google Doodle honours the 44th anniversary of the Arecibo Message
Oumuamua: Asteroid that flew past Earth could have been a spacecraft sailing past us, Harvard scientists suggest
"A more exotic scenario is that 'Oumuamua' may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization"