A cikin 1999, masu nazarin sararin samaniya a Jami'ar Jihar San Francisco da Cibiyar Harvard-Smithsonian don Astrophysics sun yanke shawarar cewa tsarin duniya guda uku ya fi dacewa da bayanan. An sanya sabbin taurari biyu Upsilon Andromedae c da Upsilon Andromedae d. Tambaya: A wace shekara aka gano tsarin duniya guda uku shine mafi kyawun bayani don dacewa da bayanan?
Shekarar 1999