What are the density and physical dimensions of the solar system's asteroid field?

Question

Is the asteroid field at uniform density and dimension across its diameter? What is the density within the asteroid belt? What are the dimensions, both average and specific, of the asteroid belt?

Answer 1

From what I can find in a fairly shallow search, the asteroid belt has a very low density, as seen below. Based on that, I cannot believe that it's uniform, but was unable to find anything one way or the other. You can find the dimensions below. The links should be a good place to start if you need more information. Also, try http://www.madsci.org/ and search their archives for "asteroid belt." They have great science questions and answers.

"Despite popular imagery, the asteroid belt is mostly empty. The asteroids are spread over such a large volume that it would be highly improbable to reach an asteroid without aiming carefully.

"Nonetheless, tens of thousands of asteroids are currently known, and estimates of the total number range in the millions. About 220 of them are larger than 100 km. The biggest asteroid belt member is Ceres, which is about 1000 km across. The total mass of the Asteroid belt is estimated to be 3.0-3.6×1021 kilograms[1][2], which is 4% of the Earth's Moon. And of that total mass, one-third is accounted for by Ceres alone." (1)

"Known as "minor planets," tens of thousands of asteroids congregate in the so-called main asteroid belt: a vast, doughnut-shaped ring located between the orbits of Mars and Jupiter from approximately 2 to 4 AU (186 million to 370 million miles/300 million to 600 million kilometers)."(2)

"If all the materials of all the asteroids were squashed up into one planet it would be smaller than our moon." (3)

"The asteroids are so widely separated that it's easy for a spacecraft to maneuver through the belt without even seeing an asteroid, much less running into one." (4) (This is taken from a section about science fiction, so the spacecraft is imaginary. )

Answer 2

I'm only writing to say "Thank You" for bringing this to my attention. I am an amateur Astronomer, and have always "ignored" the Astroid Belt that orbits the Sun between Mars and Jupiter. The thing that's most curious to me, is as to "why" does the Astroid Belt even exist where it does. I think it's a curious thing in itself that, the Astroid Belt orbits the Sun between the inner, smaller planets of the Solar System, and then outside the Astroid Belt, the "Jovian" (extremely large) bodies of mass orbit the Sun (excluding Pluto, however, which is debatable as to whether or not it can be considered a "true" PLANET of the solar system.