Apsis

Ta ny h-apsissyn çheet er ny buill s'odjey (2) as s'niessey (3) ta corpane planaidagh cruinlee (2 as 3) roshtyn, as ad kianglt rish corpane toshee ny oastagh (1).

Ta apsis (voish ἁψίς (hapsís) "aae" y Çhenn Ghreagish) çheet er y voayl s'odjey ny s'niessey jeh corpane planaidagh 'sy chruinlagh echey mygeayrt e chorpane toshee. Ta linney ny h-apsissyn çheet er y linney ta kiangley yn daa chione-leagh.

Myr sampleyr, bentyn rish cruinlee mygeayrt y Ghrian, ta ny h-apsissyn enmyssit aphelion (y boayl s'odjey) as perihelion (y boayl s'niessey). Ta apsissyn yn Eayst jeant ass y voayl s'odjey, apogee, as y boayl s'niessey, perigee, jeh'n chruinlagh eck mygeayrt yn oastagh eck, y Chruinney. T'ad aphelion (y boayl s'odjey) as perihelion (y boayl s'niessey) yn daa apsis t'ec y Chruinney as ee cruinlaghey mygeayrt e oastagh, y Ghrian. Ta ny h-enmyssyn aphelion as perihelion currit rish cruinlee Jupiter as ny planaidyn elley, ny comaidyn, as ny roltagee ayns Corys ny Greiney bentyn rish nyn gruinlee mygeayrt nyn oastagh, y Ghrian.