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To convert pc to light-years: multiply by 3.2616. To convert pc to AU: multiply by 206,265.
1 pc = 3.0857 × 10¹⁶ m = 3.2616 ly = 206,265 AU ≈ 30.857 trillion km.
For example, 1 Parsec (pc) = 3.085700e+31 Femtometer (fm).
| Parsec (pc) | Femtometer (fm) |
|---|---|
| 0.1 | 3.085700e+30 |
| 0.5 | 1.542850e+31 |
| 1 | 3.085700e+31 |
| 2 | 6.171400e+31 |
| 5 | 1.542850e+32 |
| 10 | 3.085700e+32 |
| 25 | 7.714250e+32 |
| 50 | 1.542850e+33 |
| 100 | 3.085700e+33 |
| 500 | 1.542850e+34 |
| 1000 | 3.085700e+34 |
The parsec is an astronomical unit of length defined as the distance at which one astronomical unit subtends an angle of one arcsecond.
1 pc = 3.0857 × 10¹⁶ m = 3.2616 ly = 206,265 AU ≈ 30.857 trillion km.
To convert pc to light-years: multiply by 3.2616. To convert pc to AU: multiply by 206,265.
Stellar catalogs, galaxy surveys, and cosmological distance calculations.
No known star is within 1 parsec of the Sun. Proxima Centauri is 1.30 pc away, making it the nearest star.
Pronouncing or interpreting 'parsec' as a unit of time (famously misused in Star Wars). It is strictly a distance unit.
The parsec is defined geometrically: if a star's parallax (apparent shift over 6 months) is 1 arcsecond, it's 1 pc away.
The femtometer is a unit of length equal to 10⁻¹⁵ meters, commonly used to measure the size of atomic nuclei.
1 fm = 10⁻¹⁵ m = 1,000 am = 10⁻⁶ nm. One meter equals 10¹⁵ femtometers.
To convert fm to meters: multiply by 10⁻¹⁵. To convert meters to fm: multiply by 10¹⁵.
Describing the size of protons (~0.87 fm radius) and nuclear diameters (1–15 fm depending on the element).
A proton's charge radius is approximately 0.87 fm. The diameter of a uranium-238 nucleus is about 15 fm.
Confusing femtometers with nanometers — a femtometer is one million times smaller than a nanometer.
Remember: atoms are ~0.1 nm, but nuclei are ~1–10 fm — nuclei are about 100,000 times smaller than the whole atom.



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