- See under parallax(def 2).
- the apparent displacement of an observed object due to a change in the position of the observer.
- Astronomy. the apparent angular displacement of a celestial body due to its being observed from the surface instead of from the center of the earth (diurnal parallax or geocentric parallax) or due to its being observed from the earth instead of from the sun (annual parallax or heliocentric parallax).Compare parallactic ellipse.
- the difference between the view of an object as seen through the picture-taking lens of a camera and the view as seen through a separate viewfinder.
- an apparent change in the position of cross hairs as viewed through a telescope, when the focusing is imperfect.
- Digital Technology. a 3D effect observed when images and other elements in the foreground of a screen move at a different rate than those in the background (often used attributively): parallax scrolling; Does this phone have parallax?
Origin of parallax
- an apparent change in the position of an object resulting from a change in position of the observer
- astronomy the angle subtended at a celestial body, esp a star, by the radius of the earth's orbit. Annual or heliocentric parallax is the apparent displacement of a nearby star resulting from its observation from the earth. Diurnal or geocentric parallax results from the observation of a planet, the sun, or the moon from the surface of the earth
Word Origin and History for annual parallax
1570s, from Middle French parallaxe (mid-16c.), from Greek parallaxis "change, alteration, inclination of two lines meeting at an angle," from parallassein "to alter, make things alternate," from para- (see para- (1)) + allassein "to change," from allos "other" (see alias). Related: Parallactic.
- The apparent displacement of an object caused by a change in the position from which it is viewed.
- A change in the apparent position of an object relative to more distant objects, caused by a change in the observer's line of sight towards the object. The parallax of nearby stars caused by observing them from opposite points in Earth's orbit around the Sun is used in estimating the stars' distance from Earth through triangulation.