# How far would an antimatter asteroid made inside our solar system? [closed]

Imagine right now an antimatter asteroid the size of Hawaii of extraterrestrial origin enters our solar system and is on a collision course with one of the inner planet, Mercury at a fantastic speed of 100km/s. I wonder how far would it made assuming Murphy's law holds true(excluding crash landing on object 100 times more massive than itself) ? But you know antimatter would completely and utterly annihilate ordinary matter to release huge amount of energy, term and condition apply.

• actually, this asteroid would detonate the moment it come into being, so this scenario is not anything I would regard as possible, if not unlikely – Mr. Anderson Jun 21 '20 at 6:57
• It wouldn't in a real vacuum. It would only annihilate if it came into contact with positive matter. – meaninglessname Jun 21 '20 at 9:18
• Related question. – A Rogue Ant. Jun 21 '20 at 17:00

Hawaii has a surface of $$10,500 km^2$$. Lets assume the asteroid is roughly cubic, he would have a length of $$100km$$ in every direction. For unknown asteroids its usual to take an average-density of $$2g/cm^2$$ or an average $$1.5*10^{23} particles/cm^2$$. Particle density in outer space is $$10^6 particles/m^2$$ or $$10^2 particles/cm^2$$. For simplicity we will assume al particles to be identical so one particle negates one anti-particle. By that our asteroid will lose $$1cm$$ of its length for every $$10^{21}cm$$ it moves. The asteroid is about $$10^7 cm$$ in length so it roughly gets $$10^{28}cm=10^{23}km=6,7*10^{14}AU$$ into the solar system. As the solar system is less than 2,000 AU in diameter, rhe asteroid will hit Mercury with more than 99.9% of its initial mass, the energy of this extinction event should destroy mercury.