Parsec, or pc is a real life unit used in the game measuring the distance between star systems. One parsec is equal to 30.86×1012 kilometres, or 3.26 light-years.
A parsec is calculated by drawing an imaginary triangle between the Earth, the Sun and a distant star. Where the angle at the end of the triangle closest to the distant star is one arcsecond (i.e. 1/3600th of a degree) and the side of the triangle opposite to this angle is equal to one astronomical unit (AU) the distance between the Sun and the distant star is one parsec. There are no stars within one parsec of the Earth, the closest being Proxima Centauri at roughly 1.3 parsecs.
Your spaceship is limited to travelling within a maximum distance in parsecs that your Interstellar Drive can cover in one jump.
When hovering one's cursor over the spaceship icon (above the Badge Point Promotion Bar), the distance to the center of the galaxy displayed is exaggerated by a factor of 20 when compared to the distance shown by hovering the cursor over a nearby star. For example, if one travels 10 parsecs to a star in the direction of the center of the galaxy, then the distance to the center shown in the bar below will decrease by 200 parsecs accordingly.
A possible reason for this discrepancy is that it reduces the number of stars needed to populate the Spore Galaxy by a factor of 400 (202) than the amount that is implied by the radius of the galaxy (as seen by visiting the very edge of the galactic disk).