What would happen if the asteroid belt disappeared?

Surprisingly little. The asteroid belt doesn't really do all that much - its mass is quite low and it is so widely interspersed that it is of little gravitational consequence. That said, the orbital mechanics of our solar system are chaotic on long time scales - even small changes could result in major disruptions. read more

The total mass of the asteroid belt is estimated to be 2.8×10^21 to 3.2×10^21kilograms, which is just 4% of the mass of the Moon. The Asteroid belt doesn't have enough mass to affect any other planet. read more

The main asteroid belt lies between the orbits of Mars and Jupiter and consists of a huge number of rocky objects ranging in size from a grain of sand to 950km (590 miles) across for the belt’s only dwarf planet, Ceres. read more

If Jupiter (and it's mass) were to simply disappear the asteroid belt would surely become unstable at that instant and millions of asteroids small and large would all the sudden be dominated gravitationally by the Sun's pull and their orbits would go anywhere depending on how they slammed into each other and pulled by other larger gravitational forces, potentially slinging some back into the inner solar system on a collision course with Earth. read more