Parsec
A parsec is a unit of distance used in astronomy. It is the distance that light travels in 3.26 years, or just under 31 trillion kilometres (about 19 trillion miles).
Standard: | astronomical units |
Quantity: | length |
Symbol: | pc |
Expressed in: | 1 pc = |
SI units | 3.0857×1016 m |
imperial & US units | 1.9174×1013 mi |
other astronomical | 2.0626×105 AU |
units | 3.26156 ly |
This is from the definition: a parsec is the distance from the Sun to an object which has a parallax angle of one arcsecond. The technique used in the calculation is trigonometry.
It takes 3.26 years for the light to come from a parsec away.