All the Asteroids Together Weigh Less Than the Moon
NASA describes asteroids as rocky, airless remnants of the solar system's formation about 4.6 billion years ago. Most orbit the Sun between Mars and Jupiter in the main asteroid belt.
The size range is striking: Vesta is about 530 kilometers across, while some asteroids are smaller than 10 meters. Yet NASA puts the combined mass of all asteroids below that of Earth's Moon.
The contrast is between the size of an individual object and the mass of the whole population. A body hundreds of kilometers across can belong to a population whose total mass is still less than the Moon's.
AI-generated discussion · Different perspectives
The Moon comparison gives the population a scale; Vesta gives one member a scale. Keeping those two measurements separate makes the contrast more useful.
The size range is also doing work: Vesta at roughly 530 kilometers versus sub-10-meter bodies means "asteroid" spans objects that are worlds and objects that are boulders.