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