eCosmology

What differentiates asteroids with moons? In what ways are they different?

I just saw the article on Yahoo! news regarding the 'Trojans' accompanying Neptune. My law teacher was asking about the difference between asteroids and moons...and I was primarily guessing...I know a little bit about astronomy, but not enough to properly explain the discrepancies between moons and asteroids. I told him that I believe that moons are quasi- spherical in shape usually, and that asteroids are generally smaller, and can be amorphous in shape. Is this a correct assertion? Please, if you would, explain what defines an asteroid v. a moon. Also, is there a limit to how large a moon may be- I mean, is it constituted as a planet once it passes a certain size limit? Thanks.

Public Comments

1. well asteroids are just pieces of matter floating around aimlessly. Moons actually have a gravitational pull to its planet.
2. the basic difference between a moon and an asteroid is that moons orbit a certain planet, just like our Moon or any other moons in our solar system while asteroids,i think im not sure, are just "left-overs" of what our planets used to be. they are just chunks of rocks that ,in the case of our solar system, revolve around the sun. but they are too small to be considered planets. thats why they are also called "planetoids".
3. Moons orbit planets, asteroids orbit the sun directly. Most are concentrated in the asteroid belt between Mars and Jupiter.
4. asteroids revolve around stars... n moons revolve around planets.. asteroids may be smaller or larger than a moon in size....
5. moons have a gravitational pull from the planet they're revouling around astroids do not
6. A moon is usually a smaller spherical object, circling around a larger spherical object due to it's gravitational pull. An asteroid is nothing more than a chunk of irregularly shaped rock, of varying sizes, drifting freely through space, that is, unless, they too, become caught up in the gravitational pull of some other enormously larger spherical object, or thing, such as a blackhole.
7. Shape has nothing to do with it, it's what they orbit. As another person pointed out, moons orbit a planet, asteroids orbit the sun. There are some asteroids that have become moons of Jupiter, and some of Jupiter's moons have been recaptured by the sun to become asteroids. Just FYI, the Trojans move in Jupiter's orbit, not Neptune's.