opposition
two celestial bodies are said to be in opposition when they are on opposite sides of the sky, viewed from a given place (usually Earth)
en-US/ˌɑpəˈzɪʃən/
en-GB/ˌɒpəˈzɪʃən/
two celestial bodies are said to be in opposition when they are on opposite sides of the sky, viewed from a given place (usually Earth)