Astronomers measure large distances in light-years. One light-year is the distance that light can travel in one year, or approximately 5,880,000,000,000 miles. If a star is 8.7 light-years from the Earth, how far the star is from earth?

Mar 30, 2017

$\left(51.156 \times {10}^{12}\right)$ or $51 , 156 , 000 , 000 , 000$ miles

Explanation:

If
color(white)("XXX")1" light-year" = color(red)(5.88 xx10^12)" miles"
then
color(white)("XXX")color(blue)(8.7)" light years"=color(blue)(8.7) xx color(red)(5.88xx10^12)" miles"

color(white)("XXXXXXXXXXXX")=color(green)(51.156)color(red)(xx10^12)" miles"

[...and, yes, I know that in proper scientific notation this should be written as $5.1156 \times {10}^{13}$ miles]