[lemma=our] [word=solar] □ □
[lemma=our] [word=solar] [□] □
[lemma=our] [word=solar] □? □
He also took an interest , if somewhat more abstract , in astronomy , and knew , as was common knowledge in their day , that the planets of our solar system orbit the Sun in the same direction in a relatively flat orbital plane . Based on the kinds of bodies we now see in our solar system today , it is easy to imagine the infant Earth looking like an irregular clump of cratered rock when it was about a few hundred kilometers across .