What planet was discovered two hundred years after its first observation?

G. Galileo observed Neptune in a telescope back in 1612, not knowing that this object is a planet. Le Verrier discovered Neptune by calculation only 233 years later.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.