A $26-$year$-$old biologist makes a trip to study alien life$-$forms in a distant planet $10$ light years away. The round$-$trip including a stay of $1$ year in the distant planet takes $21\mathrm{.}5$ years according to the clock on Earth. The biologist's son is $3$ years old when he leaves. Assume that the planet is not moving with respect to Earth, and the speed is the same for both the outbound and inbound part of the journey. What is the total distance traveled according to the biologist? Give your answer in light years.