Muumindani no Suisei
Genres: Adventure, Comedy, Fantasy
Type: Movie, Episodes: 1
Aired: Aug 8, 1992
Studio: Visual 80
Source: Book
Rating: G - All Ages
Synopsis:
Unusual things have been happening in Moominvalley. Moomin, Sniff and Mee leave for the Observatory on the Lonely Mountains to confirm the Muskrat's words: a comet is about to hit Moominvalley and destroy everything. On the way they meet Snufkin, the Hemulen and the Snorks and experience many adventures. 

(Source: ANN)