👉 The term "notaeum" is a Latin word that refers to an astronomical unit, which is approximately equal to 93 million miles (150 million kilometers) in length. It was discovered by Italian astronomer Nicolaus Copernicus in 1609 and later confirmed by other astronomers in the 20th century. The notaeum, or "not-a-thing" in Latin, is a term used to describe an object that cannot be seen from Earth
