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To convert Bohr radii to meters: multiply by 5.29177210903 × 10⁻¹¹.
a₀ = ℏ/(mec α) = 4πε₀ℏ²/(mee²) ≈ 5.29177 × 10⁻¹¹ m, where α is the fine-structure constant.
For example, 1 Bohr Radius (a₀) = 1.714934e-27 Parsec (pc).
| Bohr Radius (a₀) | Parsec (pc) |
|---|---|
| 0.1 | 1.714934e-28 |
| 0.5 | 8.574670e-28 |
| 1 | 1.714934e-27 |
| 2 | 3.429868e-27 |
| 5 | 8.574670e-27 |
| 10 | 1.714934e-26 |
| 25 | 4.287335e-26 |
| 50 | 8.574670e-26 |
| 100 | 1.714934e-25 |
| 500 | 8.574670e-25 |
| 1000 | 1.714934e-24 |
The Bohr radius is the most probable distance between the nucleus and the electron in a ground-state hydrogen atom, approximately 5.292 × 10⁻¹¹ meters.
a₀ = ℏ/(mec α) = 4πε₀ℏ²/(mee²) ≈ 5.29177 × 10⁻¹¹ m, where α is the fine-structure constant.
To convert Bohr radii to meters: multiply by 5.29177210903 × 10⁻¹¹.
Sets the characteristic scale for atomic sizes. Most atoms have radii of 1–3 Bohr radii.
The Bohr radius gives atoms their characteristic size of ~1 Å (10⁻¹⁰ m), explaining why matter has the volume it does.
Confusing Bohr radius with atomic radius — the Bohr radius is specific to hydrogen; other atoms have different sizes.
The Bohr radius tells you 'how big atoms are' — about 0.5 angstroms. It's the atomic analog of a ruler for atomic-scale physics.
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.



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