The Divine Sense of a God Core Realm cultivator or demon beast can easily cover an entire Solar System. Still, one must not have the wrong idea that this is too big. Back in the Mortal Realm, a Peak Divinity Realm was able to cover entire galaxies! Obviously, using Divine Sense in the Mortal Realm and the Godly Path Realm is completely different.
Another big difference is that Spiritual Energy doesn't hinder Divine Sense. That means that you can use Divine Sense to observe an entire planet as long as there are no formations preventing your Divine Sense from viewing things.