Solar analog (–0.21) for solar twin. 16 Cygni B is sometimes noted as twin, but is part of a triple star system and is very old for a solar twin at over 9 Gyr. Another way of defining solar twin is as a "habstar" — a star with qualities believed to be particularly hospitable to an Earth-like planet. Qualities considered include variability, mass, age, metallicity, and close companions. The requirement that the star remain on the main sequence for at least 3 Ga sets an upper limit of approximately 1.5 solar masses, corresponding to a hottest spectral type of F5 V. Such
Battle for Terra Battle for Terra Battle for Terra, originally screened as Terra, is a 2007 American 3D computer animated action-adventure science fiction film, based on a short film of the same name about a peaceful alien planet which faces destruction from colonization by the displaced remainder of the human race. The film was directed by Aristomenis Tsirbas who conceived it as a hard-edged live action feature with photo-real Computer-Generated Imagery (CGI) environments. The close collaboration with producing partner and investor Snoot Entertainment redirected the project to become fully animated and appeal to younger audiences. The film features the voices of Evan Rachel