This is the 14763rd most frequent Russian word.
планетарием
A "planetarium" is a building or room with a dome-shaped ceiling for projecting astronomical displays.
Here, 'планетарий' is used as the object of the verb 'ходил' to describe a place where astronomical presentations are given.
В детстве я часто ходил в планетарий, чтобы узнать больше о звездах.
In childhood, I often visited the planetarium to learn more about stars.
The word 'планетарий' serves as the subject of the sentence, highlighting its role as an institution providing educational services.
Местный планетарий организует увлекательные лекции для посетителей.
The local planetarium organizes captivating lectures for visitors.
Here, 'планетарии' is used as the location where the astronomy course is conducted.