Ypothesi:
To sympan apoteleitai mono apo ena astro kai enan planiti se troxia gyrw apo to astro. Astro kai planitis, ekteloyn kai peristrofi gyrw apo ton aksona toys kata tropo tetoio wste na vlepoyn panta thn idia plevra o enas toy allou.

Erwtiseis:
1. Mporei to parapanv na yparksei;

2. Ean nai, enas katoikos toy planiti, tha mporoyse peiramatika na diapistwsei thn peristrofi toy planiti toy gyrw apo to astro;