In Kurt Vonnegut's 'Slaughterhouse-Five', what is the name of the alien planet?

In Kurt Vonnegut's 'Slaughterhouse-Five', the alien planet is called Tralfamadore.

Billy Pilgrim says he is abducted by flying-saucer occupants and taken to Tralfamadore, a planet many light-years from Earth. The Tralfamadorians place him in a transparent geodesic-dome exhibit in a zoo, where the display resembles a furnished human home. Montana Wildhack, a film actress who has also disappeared, is later placed there with him.

The planet is central to Vonnegut's unusual treatment of time, trauma, and death. Tralfamadorians perceive four dimensions and experience every moment as existing simultaneously. Their fatalistic philosophy teaches Billy to focus on pleasant moments rather than trying to alter events. Their response to death—“So it goes”—becomes one of the novel's defining refrains.

Tralfamadore is sometimes confused with a generic science-fiction setting or with planets from other works, such as Krypton or Magrathea. It is a recurring fictional world in Vonnegut's writing, but in 'Slaughterhouse-Five' it is especially tied to Billy's fractured experience of time and the psychological aftermath of the Second World War and the Dresden bombing.