"Planetarium" (プラネタリウム, Puranetariumu) is Ai Otsuka's tenth single, which was released on 21 September 2005.

The single had great success and became Otsuka's second #1 hit on the Oricon charts, selling 316,425 copies.

In 2005, Planetarium sold 215,114 copies, making it the #41 best-selling single of the year.

"[2] "Planetarium" was featured on Ai Otsuka's studio-album Love Cook.

All tracks are written by Ai Otsuka.† Streaming-only figures based on certification alone.