So Nasa learns thru Chandra Observatory that the early Universe was DARK and some UNKNOWN event made it LIGHT?

Actually, since God and his angels are/were aliens, they took people into space and showed them the Earth. That's how they knew it was covered in water and mountains. They learned how the universe works, how stars make elements, which make up all matter, including humans. They had never seen such technology or knowledge and therefor praised these beings as gods. If you traveled to another planet and its inhabitants worshipped you, wouldn't you use your godly status to your advantage and tell them to keep worshipping you?