Parallax
The apparent shift in position of an object viewed from two different locations.
Also: stellar parallax · trigonometric parallax
Definition
Parallax is the apparent displacement of an object's position when viewed from two different vantage points. In astronomy, stellar parallax is the apparent annual shift of a nearby star's position against background stars as Earth orbits the Sun. The parallax angle is inversely proportional to the star's distance, and the parsec is defined as the distance at which a star has a parallax of one arcsecond. It is the most direct method of measuring stellar distances.
Example
“Hold your finger at arm's length and alternately close each eye: your finger appears to jump against the background—this is parallax. Astronomers use the same principle but with Earth's orbital diameter as the baseline to measure distances to nearby stars.”
Synonyms
- stellar parallax
- trigonometric parallax
- annual parallax
Images
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Related Terms
- Stellar Evolution
- Redshift
- Hubble's Law
- Distance Ladder