Q: How many meters are in one parsec? From the definition of a parsec, we can see 1 AU 150 x 10^(9) m 1 parsec = -------------- = ---------------------- tan (1 arcsec) tan ( 1/3600 degrees) = 3.09 x 10^(16) m Q: How many light years are in one parsec? One light year is the distance light travels in one year: 1 light year = (speed of light) * (one year) = (3 x 10^(8) m/s) * (365.25 days * 86400 sec/day) = 9.47 x 10^(15) m Thus, 3.09 x 10^(16) m 1 parsec = ------------------ = 3.26 light years 9.47 x 10^(15) m