Learn Dutch: Die kleine sterren draaien niet om ons. - Those small stars do not revolve around us.

In Dutch main clauses, niet usually comes after the conjugated verb (draaien) but before a prepositional phrase (om ons). It tends to sit just before the specific part of the sentence it negates or modifies, which in this case is the phrase starting with om.

Why does the adjective kleine have an -e at the end here?

We generally add an -e to adjectives when they come right before a plural noun. Since sterren (stars) is plural, the base word klein becomes kleine.

Why do we use die for "those" instead of dat?

Because sterren is a plural noun. In Dutch, all plural nouns act like de-words. That means they always use the pointing words deze (these) and die (those), even if their singular form was a het-word.

I remember using om for time, like om acht uur (at eight o'clock). Why is it used here?

While om is often used to tell time, its basic spatial meaning is "around." The combination draaien om literally means to revolve or turn around something.