Here's another of the planets: Venus. I finished that one at Pennsic. Picture it: We're all dressed as gentlemen and ladies of the middle ages (I was dressed as a gentleman, because I hate skirts). We're sitting in class, learning about the arts of the middle ages. Around me, other ladies have baskets with them, and they're knitting Viking-style socks, or tatting lace, or reproducing Elizabethan embroideries... and then there's me, making planets.
I'll add the pattern for Venus here. For 3"x3" coasters, stitch on 18-count Aida. Click on the chart to enlarge; the thread list includes the colors for all the planets series, and the colors used in this chart are marked.