The Planet Mercury Travels in an Elliptical Orbit with Eccentricity $0.703$

The planet Mercury travels in an elliptical orbit with eccentricity $0.703$ . Its minimum distance from the Sun is $8 \times 10 ^ { 7 } \mathrm {~km}$ . If the perihelion distance from a planet to the Sun is $a ( 1 - e )$ and the aphelion distance is $a ( 1 + e )$ , find the maximum distance (in km) from Mercury to the Sun.