Recall the Pythagorean theorem, which relates the three sides of a right triangle:
\[
a^2 + b^2 = c^2
\]
Where \( a \) and \( b \) are the legs of the triangle, and \( c \) is the hypotenuse. In this problem, we are given:
\[
a = 8,
c = 17,
\text{and we need to find}
b.
\]
Substitute the known values into the Pythagorean theorem:
\[
8^2 + b^2 = 17^2
\]
\[
64 + b^2 = 289
\]
Now, subtract 64 from both sides:
\[
b^2 = 289 - 64 = 225
\]
Take the square root of both sides to solve for \( b \):
\[
b = \sqrt{225} = 15
\]
Thus, the length of the other leg is \( \boxed{15} \).