(FORTUNE Magazine) – Dramatic theme songs have opened national network news broadcasts for years. To viewers they're as familiar as Walter Cronkite's face and as powerful as Tom Brokaw's hair spray. But where did they come from? Who composed them? And most important, can we buy the CD?

Before 1987, CBS opened newscasts with the simple click-clack of a typewriter, because the network felt that adding music would make the show too light. Now, like Shaft, Dan Rather has his own theme: "The Theme to the CBS Evening News With Dan Rather," written by Rick Patterson of Patterson Walz & Fox Music in Los Angeles. CBS need not worry that Patterson's piece makes light of the news. It's belted out by an 85-piece orchestra, as if to announce, "Look out, America. Here comes something serious." "There are elements of strength and credibility--a feeling that this is a place that's rock solid to go to when you want real news," Patterson says.

For its theme, NBC turned to a man more familiar with Hollywood fiction than with hard news. John Williams, composer of the Star Wars, E.T., and Superman soundtracks, wrote a grave, 80-piece symphonic-orchestra track for The Nightly News With Tom Brokaw with the overblown title "The Mission, The Sound of News." The theme first aired Sept. 9, 1985, and still runs today.

While NBC's theme has a title fit for a John Donne poem, the ABC World News Tonight With Peter Jennings theme has no title at all. Veteran music man Bob Israel, composer of the contagious The Price Is Right and Family Feud intros, penned the authoritative 1 1/2-minute song in 1977. Now ABC uses it for most of its news programs. Israel is proud to have written one of the most instantly recognizable melodies on television. "That piece means the most to me of anything I've ever done," he says. The royalties must mean a lot too: He's paid each time the theme airs. In case you need to hear the ABC song more than once a day, Israel will soon release a CD with remixes of the theme, allowing you to feel serious and important anytime you like.

--Reed Tucker