parallax

[ par-uh-laks ]

noun

1. the apparent displacement of an observed object due to a change in the position of the observer.
2. 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.
3. 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.
4. an apparent change in the position of cross hairs as viewed through a telescope, when the focusing is imperfect.
5. 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?

parallax

/ ˌpærəˈlæktɪk; ˈpærəˌlæks /

noun

1. an apparent change in the position of an object resulting from a change in position of the observer
2. 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

parallax

/ păr′ə-lăks′ /

1. 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.

Derived Forms

• ˌparalˈlactically, adverb
• parallactic, adjective

Other Words From

• par·al·lac·tic [par-, uh, -, lak, -tik], adjective
• paral·lacti·cal·ly adverb

Word History and Origins

Origin of parallax¹

First recorded in 1585–95; from Greek parállaxis “alternation, change of position” derivative of parallássein “to cause to alternate,” equivalent to para- + allássein “to change, alter, vary” (derivative of állos “other”) + -sis; para- ¹( def ), allo- -sis

Word History and Origins

Origin of parallax¹

C17: via French from New Latin parallaxis, from Greek: change, from parallassein to change, from para- ¹+ allassein to alter

Example Sentences

"Gaia increased by a factor of 10,000 the number of stars whose parallaxes are measured thanks to a massive gain in accuracy over its predecessor, the ESA Hipparcos mission," he says.

From Science Daily

The institute attracts people who are far more comfortable talking about stellar parallaxes or maintaining century-old gears than schmoozing with donors or generating buzz.

From Los Angeles Times

Because of a phenomenon called the parallax effect, Synthetaic’s founder knew that the balloon would appear as several blobs of different colors in the satellite photos.

From New York Times

A person’s principles parallax with the priorities of the Left, or of society at large.

From Washington Post

This is called parallax, and it also works on astronomical scales, changing the moon’s relative position in the sky depending on your latitude and longitude.

From Scientific American