Future ScienceThere are two possibilities regarding the universe. Either Earth is the only planet with life on it, or there is another planet somewhere supporting other creatures. Both possibilities are at least intimidating to the common mind. And when you truly realize the vastness of space, both these possibilities seem scarier. The observable universe is 92 billion light years in diameter, 9.5 quadrillion meters! This means that the closest galaxy to our very own Milky Way is a good 25,000 light years away! Because of this great distance between us and any other potential life forms, it is rather strange and unusual for an unknown foreign object to enter into our galaxy, let alone our solar system.
Credit The Space Wind