Algodoo

Our solar system without moons. Sizes of the planets (excluding the sun) are in proportion to each other, as are the distances from the sun. The distances are not in porportion with sizes though. The orbit times are not in proportion either, that's something that could be worked on. Would be cool if you could accurately see how much longer or shorter other planets take to orbit the sun.

You can make the light from sun visible by pressing Enter. This way you can see how planets shadow each other from time to time.

Planets orbit via gravity so you can create own asteroids, put them into motion and see what happens