Millimeters
The millimetre is a unit of length in the metric system, equivalent to one thousandth of a metre (the SI base unit of length).
pc =
mm *
Parsecs
The parsec is a unit of length equivalent to around 20 trillion (20,000,000,000,000) miles, 31 trillion kilometres, or 206,264 times the distance from the earth to the sun.
A parsec is also equivalent to approximately 3.26 light years (the journey distance if you travelled at the speed of light for three years and three months).
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