Ah, well, it seems I used a "fixed" background image for div#solar-system. And IE6 doesn't support "fixed" background images on anything other than the <body> element, that's what gives the illusion of transparency in Safari. IE7 does support this effect though.
You could just drop the "fixed" keyword from that declaration, and you should get the star background back, it won't look as cool as it does in Safari, but it should render.
In any case, this example wasn't really meant to be pixel-perfect. It was just meant as a quick, get your feet wet example. As you will have learned later in the book, you can fine tweak the various aesthetic anomalies present in IE with a conditional comment style sheet until you get a rendering that much more closely matches the other browsers.
Beginning CSS: Cascading Style Sheets For Web Design, 2nd Edition
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