Venus is 64in x 64in. The clever template keeps all of your bias at the center of the block so you're not dealing with wavy edges when you stitch your quilt top together. It also means you're only stitching a quarter circle curve at a time though it looks like you're working the half circle. Venus is also a great scrap buster; you can get two half-clam template pieces out of a 10in square.
The Venus template is available, but not required, to help with cutting your curved piecing. The pattern is five full color pages to help you keep track of color placement plus an additional template page.