What would you calculate to come up with the AU portion of the following...

1pc = 3.26ly = 2.06 × 10^5 AU where 1ly = 9.46 × 10^15m

I was understanding the light-year calculations fine, but I am not able to come up with 2.06 × 10^5 AU from 3.26ly

Thank You.

Question

What would you calculate to come up with the AU portion of the following...

1pc = 3.26ly = 2.06 × 10^5 AU where 1ly = 9.46 × 10^15m

I was understanding the light-year calculations fine, but I am not able to come up with 2.06 × 10^5 AU from 3.26ly

Thank You.

anonymous · Answer

The simplest definition of an AU (though not strictly correct) is the semi-major axis of the earth's orbit around the sun - 149 597 870 700m. 

to convert ly to AU's: 
3.26 ly * (3 x 10^8m/s * 1 yr)/ly * 365.25d/yr * 24 h/d * 3600s/h * 1AU/149597870700m 

This is just a "chain-link" conversion

anonymous · Answer

Stan, thank you for the reply.

I understand all of that except where you got (3 x 10^8m/s * 1 yr) from.
What does that represent?

Thanks.

anonymous · Answer

he distance light travels in a year is its speed times the time (d = v*t). Speed is 3 x 10^8 m/s, time is 1 year