Dictionary of Space Concepts

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Definitions

Short Definition
Parallax is an angular apparent shift in an object’s position when it is observed from two separate viewpoints. Half the angle between two lines of sight is the magnitude of parallax.

Detailed Definition
The principle of parallax is widely used to measure large distances, i.e. to far away stars and planets. The Stellar parallax method allows one to obtain measurements from trigonometric parallax. Observations of the celestial body are taken from two opposite points of the Earth’s orbit (with a 6-month gap), the apparent movement of the object is considered with respect to its distant background. An isosceles triangle with the base of 2 astronomical units is then formed by the lines of sight. The distance to the object is equal to 1 AU over the parallax angle measured.

Etymology
From Ancient Greek παράλλαξις (parállaxis)“alteration”

Sample Sentences

Eyes of live creatures with binocular sight, humans included, exploit parallax to perceive depth and measure distances.

Translations of Terms/Concepts into Partner Languages

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Additional Translations of Terms/Concepts into Other Languages

Russian
параллакс

Ukrainian
паралакс

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