How did Sumerians know about the 12 planets

ANCIENT MYSTERIES - The ancient Sumerians knew 12 planets. Only 5 planets of our solar system are visible with the unaided eye. And one of them, Uranus, was (re)discovered only in the 17th century and named a planet in the 18 century.

Sumerian tablet

Neptune, which can only be seen through a telescope, was discovered in the 19th century. Pluto was discovered as late as 1930. In 2006 a new definition of planets was proposed by astronomers, which would result in a total of 12 planets for our solar system.

The Sumerians lived some 5,000 years ago. They had no telescopes that we know of. Yet they clearly knew of 12 ‘celestial bodies’, including the sun and the moon. They depicted the 12 planets and wrote about them on clay tablets. The Sumerians described not only the existence of these celestial bodies, but knew exactly their names and roles in the solar system and the universe. Were they masters of mathematics and astronomy? Some say that the Sumerians must have received information from aliens, from outer space.