We should keep in mind the difference between "ต่างดาว" and "ต่างด้าว". The former means "of a different star" as in "มนุษย์ต่างดาว" (extraterrestrial being) and "คนต่างด้าว" (a foreigner or alien, i.e., a person who does not have citizenship in the country where he resides).
compare http://www.thai-language.com/id/224291#def2 and http://www.thai-language.com/id/131731#def2 .