Astronomers use a measure of distance called the parsec, abbreviated pc, more often than the lightyear, another measure of distance. A star that is one parsec away has a parallax of one second of arc relative to the Earth’s orbit about the sun. (Parallax is the apparent displacement of a body due to its observation from two different positions.) One parsec is about 3.26 lightyears. Determine Hubble’s constant in km/s per Mpc.

Strategy We need to use conversions and the value of the Hubble constant. One Mpc is a megaparsec or 10^{6} pc.