I am a 17 year old high school student in Alabama, and after my astronomy test today, I decided to calculate the mass of all interstellar gas and dust in our solar system (under the assumption that the solar system extends to 55,000 AU in all directions) and I calculated the mass to be a combined 6x10^24 kg (I believe. I left my notes at school.), which is less than the 2x10^30 kg of the Sun. I excluded the mass of the planets, moons, asteroids, and comets to be negligible, and I'm curious as to how close I actually am to the correct number, if anyone knows. p.s., I was doing this because my astronomy teacher said that the Sun composed 99.9% of the Solar System, by mass, and I suggested that the mass of the gas and dust would be greater, and he agreed that it was possible. in the end, he was right in the first place, with the Sun (in my approximation) composing 99.00% of the Solar System. just curious to your thoughts.