B
Boycott
Guest
Why the first two answers both gave you an identical answer... for MARS and Neptune, is beyond my realm of logic.
Both orbit Mercury and Neptune orbit the sun. So, they will be closer, say, when Mercury is at aphelion and Neptune is at perihelion and Neptune is at conjunction as seen from Mercury. <--- All that astronomy jargon basically means, when Mercury is farthest from the sun, and Neptune is closest to the sun, and they are both on the same side of the sun, they will be at their closest.
Dana M. gave you some good statistics for the semimajor axis of each.
Both orbit Mercury and Neptune orbit the sun. So, they will be closer, say, when Mercury is at aphelion and Neptune is at perihelion and Neptune is at conjunction as seen from Mercury. <--- All that astronomy jargon basically means, when Mercury is farthest from the sun, and Neptune is closest to the sun, and they are both on the same side of the sun, they will be at their closest.
Dana M. gave you some good statistics for the semimajor axis of each.