Final answer:
Astronomer Giuseppe Piazzi discovered the missing planet between Mars and Jupiter through mathematical calculations, naming it Ceres. This led to the discovery of asteroids in similar orbits.
Step-by-step explanation:
The missing planet between Mars and Jupiter was discovered through the mathematical calculations of astronomer Giuseppe Piazzi in 1801. He predicted the existence of this planet and named it Ceres. This discovery led to the identification of asteroids or minor planets in similar orbits.