Centre of direct/retrograde motion

https://www.theplanetstoday.com/

The Earth is about to overtake Mars at our relative closest distance so it will appear larger and brighter than at any other time in our mutual orbits around the Sun -

https://apod.nasa.gov/apod/ap160915.html

When the inner planets overtake us at the centre of retrogrades they appear darkest and lovingly understood during transits -

https://www.youtube.com/watch?v=_7U5VbasKr4&t=23s

The perspectives of direct/retrograde motions of the planets split between the faster and slower moving planets so this observation is now relative as we can see the Earth from the surface of Mars as a faster moving planet which will too show a dark phase at planetary transit.

No harm teaching the necessary partitioning at star parties as this is an enjoyable and decent thing to do.