Stars can be seen with the naked eye, but planets orbiting other stars are incredibly difficult to see, even with the most powerful telescopes ever made. It wasn't until 1992 that astronomers imaged an exoplanet, meaning a planet in another solar system; prior to that, some astronomers thought our solar system may be unique, and thought planets were perhaps rare.
By the 2010s, however, exoplanet discoveries were so frequent as to become quotidian; now, there are over 9,000 likely or confirmed exoplanets, according to NASA. Because of a selection bias that favors large bodies that are close to their parent stars, many of these planets are larger than Jupiter. Smaller bodies are much harder to see — and when it comes to bodies smaller than planets, like moons or asteroids, there are candidate bodies though none that are actually confirmed.
