Our eyes can only see as far as the horizon, due to the curvature of the Earth. For instance, an observer standing on a hill 100 feet (30 m) in height, their horizon is at a distance of 12.2 miles (19.6 km). Obviously, without the restriction of a horizon, we can look out far into space on a dark night and see our moon and many distant stars and planets with the naked eye - even better with a telescope. So the answer is we can see much further into space than our moon and sun.