Figure 4-6 RIVUXG Asteroid Family Portrait A collage of asteroids, shown to scale, from largest to smallest: Vesta, 330 mi (530 km) across; Lutetia, 81 mi (130 km); and Mathilde, Ida (and its moon Dactyl), Eros, Gaspra, 2867 Steins, and Itokawa. Most asteroids are too small to have enough gravity to pull them into spherical shapes.