A unit of distance in astronomy equal to 3.26 light-years, itself equal to about 19 trillion miles and derived from the distance a star would have to be for it to exhibit a parallax angle of 1 second of arc (hence par-sec) against the background stars as Earth orbits from one side of the Sun to the other [text coloring by post author].Tyson further tells us that the Oxford professor and former astronomer royal Herbert Hall Turner coined the term parsec. In 1930, Turner also played his part in promoting the name Pluto for a cosmic object discovered by Clyde Tombaugh and at first referred to as Planet X.
The Google calculator result for 1 parsec:
1 Parsec = 3.08568025 × 1016 meters
Still not satisfied? Find some nice video animations and lectures at wn.com/Parsec (for example Parsec definition and What is a Parsec?).
Keywords: physics, astronomy, units, history
References and more to explore
 Alan Isaacs: Oxford Dictionary of Physics. Oxford University Press, Oxford and New York, 2003 (reissued fourth edition).
 Neil deGrasse Tyson: The Pluto Files. W. W. Norton & Company, New York and London, 2009; page 9, 11.