From [Wikipedia Article on Parsec](https://en.wikipedia.org/wiki/Parsec):

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> The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System. A parsec is obtained by the use of parallax and trigonometry, and is defined as the distance at which one **astronomical unit** subtends an angle of one arcsecond, i.e. 1/3600th of a degree.
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From [Wikipedia Article on Astronomical Unit](https://en.wikipedia.org/wiki/Astronomical_unit):

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> The astronomical unit (symbol: au, ua, or AU) is a unit of length, roughly the distance from Earth to the Sun and equal to about 150 million kilometres (93 million miles). However, that distance varies as Earth orbits the Sun, from a maximum (aphelion) to a minimum (perihelion) and back again once a year. **Originally conceived as the average of Earth's aphelion and perihelion**, since 2012 it has been defined as exactly 1.495978707×1011 m. The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length, the parsec.
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So, as *Star Wars* happens in a galaxy far far away, why are they using the average distance between Earth and the Sun as a distance of measure and how do they know it?