But that's not it.
It is the remains of a planet that never was.
A bit dramatic, but stay with me:
There are billions of asteroids in the belt region. But when we sum up the total mass of the system, it comes out merely to be around 4% of that of our moon.
This is enough to ascertain that there was never a planet that could have collided and created asteroid belt. So, then what could it be?
Answer is simple and hidden in the story of foundation of our Solar dynasty.
4.6 Billions Years ago, when gas and dust from solar nebula was bundling up to light up our Sun, other planets were settling up nearby in their respective orbits.
Jupiter was huge and had an aspiration of becoming a companion star to the Sun (not that it ever could have enough matter to become one). But in the meanwhile Saturn, Uranus and Neptune also took away their chunck of support.
So, Jupiter had to settle as the largest gas planet of the solar synasty. Since it was big and formed fast, and lost support, it was furious (Fact: It exerted strong gravitational influence on nearby regions).
It did not allow settlement activities nearby. It even moved around the dynasty to gather support (Fact: Gas planets changed orbits during early phases of Solar System), but it only created chaos.
And this chaotic dynamics of early solar system, flung away much of the mass hear and there.
Specially in the belt region.
Resulting the belt region into a bunch of nomadic tribe, unable to allign themselves with any one planet.
Some of these nomads (around a million or so), some from else where joined the Jupiter’s party and got stuck into its Lagrangian points.
These asteroids are known as Trojan asteroids.
Some confuse these Trojan asteroids as the real astroid belt. I have seen some post declaring them as real astroid belts, but they are not.
These Lagrangian points are gravitational pockets where Jupiter catches any incoming astroid protecting the inner planets from imminent danger.
However, when Jupiter’s gravity is disturbed, some of these asteroids loosen up and fall towards the Sun, passing through the Earth.
So you see, how planets have a control on us?!