Final answer:
Ceres is the largest asteroid, with a diameter just under 1000 kilometers, but is now considered a dwarf planet. The number of asteroids grows exponentially with smaller sizes. The Dawn mission provided extensive data by orbiting both Ceres and Vesta.
Step-by-step explanation:
The largest asteroid in our solar system is Ceres, with a diameter just under 1000 kilometers. Ceres was initially classified as a planet upon its discovery, but it was later deemed an asteroid and is now categorized as a dwarf planet, similar to Pluto. Although reclassified, Ceres is still often referred to as the largest of the asteroids, compared with others like Pallas and Vesta, which have diameters of about 500 kilometers. The asteroid population increases exponentially with smaller sizes, indicating there are many more small asteroids than large ones. As of 2016, astronomers had discovered nearly a million asteroids. The Dawn spacecraft conducted the most comprehensive mission to date by orbiting Ceres and Vesta, providing valuable information about their composition, structure, and history.