What are the similarities and differences between a parsec and a light year?

1 Answer
Feb 14, 2016

Both are units for expressing great distances in-between space bodies. Light year is related to Earth year and speed of light. Parsec is related to parallax angle and Earth-Sun distance, AU.


Light year can be reduced to light second = 299792458 km/s, as unit. Average Earth-Sun distance AU = 149597870.7 km. Easily, AU = 499.005 light seconds. For stellar distances, mega parsec = 1 million parsec can be used as alternative to light year.1 parsec = 3.27925 light year..