Question

one parsec equals 3.26 light years, where a light year is the distance light travels in one year. if the speed of light is 186000 mi/s, how many parsecs does it take for light to reach Mars from Earth, which is 60 million kilometers away? (1 km = 0.621 mi) Use "E" for scientific notation.

Answer 1

Parsec is a unit of distance (as stated 1 Parsec = 3.26 light years, wihch is 3.26 times the distance run by light in one year).

That distance is:

1 parsec = 3.26 mi× 186,000 mi/s × 3600 s/h × 24 h/day × 365 day/ year × 1 year = 19,122,168,960,000.mi.

So, the question of how many parsecs it takes for light to reach Mars from Earth does not make sense because parsecs is not a unit of time.


You can calculate how many parsecs is equivalent to the distance between Mars and Earth, 60,000,000 km. For this you can first calculate the  equivalence of which you do in this way:


60,000,000 km × 0,621 mi/km  × 1 parsec / ( 19,122,168,960,000 mi) = 1.94E-6 parsecs.