Join two curious kids as they explore their backyard, and contemplate their place within our vast universe in this adorable picture book that's full of comparisons to help kids understand cosmic size.If Pluto was a pea… the Sun would be like a tent, Mercury would be a marble, and Earth would be a golf ball. Pluto is the smallest planet in our solar system, but how small is small? As it turns out, it only takes the contents of a lunchbox and a backyard to find out.