Mars' orbit (not drawn to scale here) is elliptical and off-center in relation to the sun.
Earth's orbit is somewhat less elliptical.
when Mars is at its nearest point to the sun and Earth is at its furthest point, but both are on the same side of the sun, we have a close encounter.

[This message was edited by Inda on Wednesday August 27th, 2003 at 02:13 PM.]