1) Counterearth 2) English-language journal 
Antichthon is the peer-reviewed academic journal of the Australasian Society for Classical Studies. The focus of the journal is ancient Greece and Rome, however, its scope is broadly defined so as to embrace the ancient Near East and the Mediterranean from the beginnings of civilisation to the Early Middle Ages. ...
hypothetical second Earth on the opposite side of the sun
• (n.) Inhabitants of opposite hemispheres. • (n.) A hypothetical earth counter to ours, or on the opposite side of the sun.
An·tich'thon noun ; plural Antichthones [ Greek ...; ... against + ... the earth.] 1. A hypothetical earth counter to ours, or on the opposite side of the sun. Grote. 2. plural Inhabitants of opposite hemispheres. Whewell. 
antichthon 1. A hypothetical earth which is counter to ours, or that is on the opposite side of the sun. 2. Inhabitants of opposite hemispheres.
counterearth.