The first rung of the cosmic distance ladder. As Earth orbits, nearby stars appear to shift — and that tiny angle gives their distance directly.
Stellar ParallaxLive
the first rung of the distance ladder
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As Earth orbits the Sun, a nearby star appears to shift against the distant background. Half that annual shift is the parallax angle p, and distance in parsecs is simply 1/p (with p in arcseconds). One parsec is the distance giving a one-arcsecond parallax.
Reading this result: A parallax of 0.100″ puts this star 10.0 pc (32.6 ly) away — because distance is 1/p, halving the angle would double the distance, so the tiniest angles mark the most distant stars.
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How it works
Stellar parallax is the apparent shift of a nearby star against distant background stars as Earth moves across its orbit. The distance in parsecs is simply 1/parallax, with the parallax angle measured in arcseconds. This is the only direct geometric distance measurement in astronomy, and it calibrates everything beyond.
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The math, the assumptions, real-world uses, or a code translation — explained for this exact simulation.
Is this stellar parallax distance tool really free?▾
Yes. Stellar Parallax runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?▾
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
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How accurate are the results?▾
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.