http://earthsky.org/space/why-does-the-sun-shine http://earthsky.org/space/why-does-the-sun-shine http://earthsky.org/space/why-does-the-sun-shine http://earthsky.org/space/why-does-the-sun-shine http://earthsky.org/space/why-does-the-sun-shine http://earthsky.org/space/why-does-the-sun-shine