Distance to Proxima Centauri
| Value | 4.0175e16 m |
| Status | Measured: ± 3,000,000,000,000 m (0.000075 relative) |
| Source | Gaia DR3 parallax, 768.07 ± 0.05 mas |
| Categories | Astronomicalstellar |
| Planck length | 2.4856845e+51 lP |
| femtometer | 4.0175000e+31 fm |
| picometer | 4.0175000e+28 pm |
| bohr radius | 7.5919747e+26 a0 |
| angstrom | 4.0175000e+26 Å |
| nanometer | 4.0175000e+25 nm |
| micrometer | 4.0175000e+22 μm |
| thou | 1.5816929e+21 thou |
| point | 1.1388189e+20 pt |
| millimeter | 4.0175000e+19 mm |
| pica | 9.4901575e+18 pc |
| centimeter | 4.0175000e+18 cm |
| inch | 1.5816929e+18 in |
| decimeter | 4.0175000e+17 dm |
| hand | 3.9542323e+17 hh |
| link | 1.9970870e+17 li |
| foot | 1.3180774e+17 ft |
| US survey foot | 1.3180748e+17 ftUS |
| yard | 4.3935914e+16 yd |
| meter | 4.0175000e+16 m |
| fathom | 2.1967957e+16 ftm |
| rod | 7.9883480e+15 rd |
| chain | 1.9970870e+15 ch |
| cable length | 216,927,650,000,000 cb |
| furlong | 199,708,700,000,000 fur |
| kilometer | 40,175,000,000,000 km |
| mile | 24,963,588,000,000 mi |
| nautical mile | 21,692,765,000,000 nmi |
| league | 8,321,195,900,000 lea |
| megameter | 40,175,000,000 Mm |
| Earth radius | 6,305,917,400 REarth |
| light-second | 134,009,380 ls |
| lunar distance | 104,513,800 LD |
| solar radius | 57,747,592 Rsun |
| light-minute | 2,233,489.6 lmin |
| astronomical unit | 268,553.29 AU |
| light-year | 4.2465009 ly |
| parsec | 1.3019831 pc |
| kiloparsec | 0.0013019831 kpc |
| megaparsec | 0.0000013019831 Mpc |
| gigaparsec | 1.3019831e-09 Gpc |
Learning zone
Every distance in this library beyond the solar system starts from geometry like this one: Proxima's parallax of 768.07 milliarcseconds — the largest of any star, yet still under a thousandth of a degree — inverts to 1.302 parsecs. Gaia measures it to one part in 15 000, so the nearest star's distance is known to about ±3 billion km, roughly the radius of Neptune's orbit. Robert Innes found the star in 1915 and named it for its proximity; it has held the title ever since and will keep it for about 25 000 more years.
The number is also the yardstick of interstellar ambition. Voyager 1, the fastest outbound object, covers this distance in 75 000 years; the Breakthrough Starshot concept of laser-driven gram-scale sails at a fifth of light speed was formulated around reaching precisely this star within a generation. Its planet Proxima b, found in 2016, is the nearest possible target for the question of life elsewhere.