Almost 30 years ago, the late astronomer Carl Sagan wrote “we are creatures of the cosmos… we are star stuff.” This is not merely a bit of poetic license. The death throes of large stars are the workshops where the heavier elements (e.g., carbon and iron) that make up our bodies were once made. There is nothing in us, except possibly a few hydrogen atoms in the water in our tissues, that was not once in a star. Mr. Sagan eloquently captured this idea once and for all with his memorable turn of phrase.

This is also one of the core ideas visited by the Life and Death of a Star, episode 10 of the 13-part series The Universe on The History Channel. During this fairly fascinating hour of television, we learn about the biology of stars — how they are born, live, and die. And make no mistake: stars live very interesting lives.

Consider, for example, the fundamental thing that makes one star different from another: size. Size is everything to a star. Be born big, and you end up being blue, aging very fast, and dying in a massive explosion that may produce a black hole. Be born small, and you end up red, live for a very long time, and may turn into a white dwarf. Be somewhere in between, and you end up like our Sun — yellow, of medium lifespan, and may become a neutron star. Three very different processes, all dependent on how much hydrogen is present when a star is born.

Being a star also involves a perpetual struggle between two opposing forces. Hydrogen fusion powers stars, producing tremendous energy through a sort of continuous, controlled explosion. This explosion wants to fling stellar material away from the center of the star, but stars are huge — so huge that gravity reins in and contains the material of the star in a bright ball. That nearly eternal tension between the explosive power of nuclear fusion and gravity governs the behavior of the star through much of its life and death.

Life and Death of a Star is an engaging piece of television. Other programs with strong cosmological components, such as Mr. Sagan’s Cosmos and Stephen Hawking’s A Brief History Of Time, have covered much of this material before, and sometimes done it better. The presentation of the material is also sometimes a bit uneven and weighed down by overly earnest efforts to make the physics understandable to everyone. The episode still shines brightly, however, because of its source material. Science has learned a great deal about the life and habits of stars since anyone last tackled this subject in a lucid, general way. The presentation of that material alone makes this an hour worth viewing.

The Universe series episodes air on Tuesday at 9pm on the History Channel through September 4, 2007, and will be available on DVD October 30, 2007.