If you are fortunate enough, and are willing to travel to remote locations, you may at some point experience a solar eclipse. You can see Jupiter with its great red spot change hourly, study the cloud bands and watch its moons shuttle back and forth. Study Saturn and its splendid ring structure, watch Venus and Mercury as they go through their moon-like phases. Observe Mars and see its polar cap changes or watch the dust storms and deserts bloom with life. Galaxies exist in a variety of sizes with regular and irregular shapes.
Magnificent comets are routinely visible through telescopes .
These are pairs of stars orbiting around a common center of gravity, often of different and contrasting colors. What you can see is dependent on a lot of factors. The most important of these for astronomy is aperture. You won't be able to see the American flag on the surface of the moon or black holes. Most telescopes can be used to see things on the Earth.