# Parsecs to Astronomical Units (pc to au) Source: https://www.unitconvertercalculator.com/length/parsecs-to-astronomical-units/ **1 pc = 206264.8062471 au** One parsec equals approximately 206,265 astronomical units. This is the fundamental conversion in stellar astronomy, connecting the solar-system unit (AU) with the stellar-distance unit (parsec). 1 parsec is the distance at which 1 AU subtends 1 arcsecond. ## Formula Convert Parsecs to Astronomical Units ## Conversion Table | Parsecs (pc) | Astronomical Units (au) | |---|---| | 0.001 pc | 206.2648062471 au | | 0.01 pc | 2062.648062471 au | | 0.1 pc | 20626.48062471 au | | 0.5 pc | 103132.40312355 au | | 1 pc | 206264.8062471 au | | 1.3 pc | 268144.24812123 au | | 2 pc | 412529.61249419 au | | 5 pc | 1031324.0312355 au | | 10 pc | 2062648.062471 au | | 100 pc | 20626480.62471 au | | 1000 pc | 206264806.2471 au | | 10000 pc | 2062648062.471 au | | 30000 pc | 6187944187.4129 au | ## Units ### Parsec (pc) The distance at which one astronomical unit subtends an angle of one arcsecond. Approximately 3.26 light-years or 30.857 trillion kilometers. The standard unit in professional astronomy. ### Astronomical Unit (au) Exactly 149,597,870,700 meters by IAU 2012 definition. Roughly the average distance from the Earth to the Sun. Used for distances within our solar system. ## Background 1 pc = 206,265 AU. Proxima Centauri at 1.3 pc is about 268,000 AU. The Oort Cloud extends to about 100,000 AU (0.49 pc). The parsec-to-AU conversion defines the transition from solar system to interstellar space. ## Good to Know The number 206,265 connects Earth's orbit to the stars. It is the conversion factor that transforms solar system geometry into stellar distances. Every stellar distance ever measured by parallax passes through this number. It is arguably the most important number in observational astronomy. ## FAQ ### How many AU are in 1 parsec? One parsec contains approximately 206,265 AU. This comes directly from the parsec's definition: the distance at which 1 AU subtends 1 arcsecond of parallax. ### How is the parsec defined using AU? 1 parsec = distance where 1 AU (Earth's orbital radius) creates 1 arcsecond of parallax angle. It is a geometric definition connecting Earth's orbit to stellar distances. ### Which is larger, 1 AU or 1 parsec? 1 parsec is about 206,265 times larger than 1 AU. The AU measures within the solar system; the parsec measures beyond it. ## Non-Frequently Asked Questions ### How many Earth orbits fit between us and the nearest star? Earth's orbit has a radius of 1 AU. Proxima Centauri is 268,000 AU away. That is 268,000 Earth-orbit-radii, or about 42,600 Earth-orbit-diameters. If Earth's orbit were a coin, you would need 42,600 coins to reach the nearest star. Stars are far apart even in solar-system units. ### Why is 206,265 such an important number? Because there are 206,265 arcseconds in a radian (360 degrees x 3,600 arcseconds/degree / 2 pi). The parsec is 1 AU x 206,265 = 1 radian of distance at 1 arcsecond resolution. It is pure trigonometry. The number 206,265 is pi's gift to astronomy. ### Could the solar system fit inside 1 parsec? Neptune orbits at about 30 AU. The Oort Cloud extends to about 100,000 AU. 1 parsec is 206,265 AU. So the entire solar system (including the Oort Cloud) fits about twice inside 1 parsec. The nearest star at 1.3 pc is about 2.6 solar systems away. 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