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One parsec, the distance at which a star shows 1 arcsecond of parallax, equals about how many light-years?

About 3.26 light-years.

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  1. Exactly 1 light-year
  2. About 1.5 light-years
  3. About 3.26 light-years ✔

Why: Parsec is short for parallax arcsecond. Using Earth's orbit as the baseline, a star 206,265 AU away shifts by 1 arcsecond. That is about 3.26 light-years, or 31 trillion km.

Huh, didn't know that: Despite a famous movie line, a parsec is a unit of distance, not time.

The dad joke
I'd tell you a parsec joke, but it's a bit of a stretch. About 3.26 light-years, actually.
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References

Answer: About 3.26 light-years. Parsec is short for parallax arcsecond. Using Earth's orbit as the baseline, a star 206,265 AU away shifts by 1 arcsecond. That is about 3.26 light-years, or 31 trillion km.

  1. OpenStax Astronomy 2e, 19.2 Surveying the Stars openstax.org/books/astronomy-2e/pages/19-2-surveying-the-stars
    The answer turns out to be 206,265 AU, or 3.26 light-years.
    Checked 2026-10-10.

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