1. The problem asks to express the product of $1.7 \times 10^6$ watts and $5 \times 10^5$ watts in gigawatts (GW). 2. First, multiply the numbers and powers of ten separately: $$ (1.7 \times 10^6) \times (5 \times 10^5) = 1.7 \times 5 \times 10^{6+5} = 8.5 \times 10^{11} \text{ watts} $$ 3. Recall that 1 gigawatt (GW) equals $10^9$ watts. 4. To convert watts to gigawatts, divide by $10^9$: $$ 8.5 \times 10^{11} \div 10^9 = 8.5 \times 10^{11-9} = 8.5 \times 10^2 = 850 \text{ GW} $$ 5. Therefore, the product expressed in gigawatts is $850$ GW.