Can bạn watch the stars when the sun is up?

No, because bạn shouldn't look at the sun! Your eyes will light on ngọn lửa, chữa cháy and burn if bạn do that.

..That's just one star, though. But seriously, it depends where the sun is in the sky. When it's rising/setting, maybe. When it's up in the sky, middle of the day, I doubt it. bạn are able to sometimes see the moon, though!

The stars on TV/Movies yes.

Stars in the sky no.

Yes.