mason's planets sidewalk chalk set Little Chalk Solar System mason's planets sidewalk chalk set Little mason's planets sidewalk chalk set Little. Our planets are out of this world! What could be better for drawing and learning than a full nine piece solar system! $2 from every sale of Mason's Planets will go to the Children's Hospital of Philadelphia to support Autism research. Mars, Venus, Earth, Mercury, Neptune and Pluto have two layers of color an outer core and an inner core. Saturn, Jupiter, Uranus have three layers an inner core, outer core and crust. Each order includes: A full solar system of nine planets even Pluto! Dimensions: Large planets are 2. 5 inches in diameter & small planets are 1. 5 inches in diameter