After successfully teaching N the world continents using Montessori method, i decided to use the same methodology to teach him the solar system. I searched and printed out the different planets, cut and paste them on a black background, like so. I also made my own labels by writing each planet name on a small cut out cardboard (nice size for the toddler's hands).
Using labels, i taught him the planets and their respective positions in the system. N picked up the concept quickly and was able to identify the planets & match the labels with its respective planet after just 2 lessons!