What does pericynthion mean?
A pericynthion is the point at which a spacecraft or any other man-made object launched from earth into the orbit of our moon is nearest to the centre of the moon.
When a spacecraft is in the orbit of any celestial object (in this case our moon), it isn't always at the same distance away from the centre of the moon because of a couple of different factors such as:
- The moon isn't a perfect sphere
- The spacecraft won't go around the moon in a perfect circle.