Le site de vulgarisation scientifique de l’Université de Liège. ULg, Université de Liège
Apastron – Perisastron

In astronomy, when one body gravitates around another, it in reality turns around the centre of the system’s common mass. Its orbit, which generally has the form of an ellipsis, has a perisastron and an apastron. The perisastron is the orbital point at which the two bodies pass the closest to one another, whilst the apastron is the orbital point where the distance between the bodies is at its maximum.


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