Subject: Why doesn't the earth just fall straight to the sun?

I understand (more or less) Einsteins theory behind gravity, but i don't see why
they don't go straight into the sun. My science teacher said the earth has its
own dip, and the sun's pull isn't strong enough to pull the earth over the hill
caused by the dip. But the earth has to go over the hill while orbiting too...
I was hoping you could further clarify this for me. THank you!

Re: Why doesn't the earth just fall straight to the sun?