The line of sight of the brightest star in the sky,
Sirius has a maximum parallax angle of `delta = 0.74 pm 0.02` arc second when observed at six month interval. The distance between two positions of earth (at six - month interval) is `r = 3.000 xx 10^(11) m`
Calculate the distance of Sirius form the Sun with uncertainty, in unit of light year. Given 1 `1y = 9.460 xx 10^(15) m , pi = 3.14`
