Just for test

An exoplanet (or extrasolar planet) is a planet which orbits another star, outside of our own solar system. A few decades ago, it wasn't even known if other solar systems existed, but now they have been found to be common in our galaxy and the universe.
For thousands of years, the observation of planets was limited to those in our own solar system, as they were the only ones that could be seen or detected. During that time our knowledge of the solar system has grown immensely.