Apsis
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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.