If you want to go outside the cosmos, consider a "pop culture" figure. I, for one, enjoy the science of Alton Brown's shows. My 3 yr old loves AB as well. My mother is a family and consumer sciences teacher and uses his shows to demonstrate the science behind cooking. I'm a physician and enjoy the way he takes difficult topics and presents them in a (off-the-wall) manner for everyman. Don't limit your science to astronomy...