They are discovered when they dim a star they pass by is true Exoplanets.
The exoplanets are the planets that move round stars except the sun.
Exoplanets they are also called extra solar planets which means that these planets orbit around other planets except the sun.
Exoplanets is not part of the solar system because in the solar system, the planets revolve around the sun.
Examples of exoplanets are Kepler-186f , 55 Cancri e.
Therefore, Exoplanets are discovered when they dim a star they pass by is true Exoplanets.
For more details on Exoplanets, check the link below.
https://brainly.com/question/21880131.