Of or pertaining to a parallax.
Adj. form of → parallax.
Fr.: angle parallactique
Of an object in the sky, the angle between the → celestial pole, the object, and the → zenith. Since parallactic angle describes the orientation on the sky of the object for a particular observer, it can be an important quantity in some observations.
Fr.: ellipse de parallaxe
The path on the sky of the apparent position of a star as seen from the Earth, due to the Earth's annual motion around the Sun.
Fr.: inégalité parallactique
An irregularity in the Moon's motion caused by the Sun's gravitational attraction, which sets the Moon ahead or behind its normal orbital position. The Moon is about 2 arcminutes ahead of its expected position at first quarter, and a similar amount behind at last quarter.
Fr.: mouvement parallactique
The proper motion of a star due to the effect of the Sun's motion relative to the → local standard of rest.