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  1. Home
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  3. Parallax
Observational Astronomy

Parallax

Definition

The apparent displacement of a nearby object against a distant background viewed from two positions. Stellar parallax measures distances to nearby stars by observing their shift as Earth orbits the Sun. It is the most direct method of measuring astronomical distances.

Related Terms

Parsec

A unit of distance equal to about 3.26 light-years (30.9 trillion km). Derived from parallax of one arcsecond. Professio...

Light-Year

The distance light travels in one year in a vacuum: approximately 9.461 trillion km. Used to express astronomical distan...

Astronomical Unit

A unit of measurement equal to the average distance between Earth and the Sun, approximately 149.6 million kilometers (9...

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