Shin Taketori Monogatari: 1000-nen Joou(1980)

A new discovered 10th planet, called Lametal, will collide with earth on 9th September 1999. While the impact won't affect the giant ice planet critically, earth will be destroyed.
Yayoi, daughter of Lametal's queen and entrusted with the mission to abduct a large number of humans for slavery, befriends the orphaned boy Hajime and starts to question the intentions of her mother. Together with her human family and friends, she takes up the fight against Lametal and searches for a way to avoid earth's destruction.