Why is a parsec named so?
Parsec is an acronym for 'parallax second'. It is a unit of distance used for measuring distances of deep sky objects. 1 parsec = 3.26156 light year.
Imagine an isosceles triangle of opposite side 1 AU against the angle 1 second = 1/3600 degree. The equal sides measure 1 parsec. A larger unit is mega parsec = 1 million parsec..