Aliens could be trapped on their own planets
Aliens could be submerged on waterlogged planets
Astronomers searching for extraterrestrial life are now putting their focus on Hycean planets - ones totally covered by oceans that have no sound.
Professor Elio Quiroga, of the Universidad del Atlantico Medio in Spain, explained that communication "might never emerge" in the waterlogged environments "even though it could be home to a fully developed civilisation".
The academic has also theorised that intelligent little green men are living on gigantic planets and have no chance of getting away due to the gravitational pull and higher escape velocities.
Professor Quiroga added: "Intelligent species on these planets would never be able to travel into space due to sheer physical impossibility."