Gold

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Taurus plunges headfirst toward the western horizon on March evenings. A pattern of stars known as the Hyades forms his V-shaped face, with the star Aldebaran representing his bright orange eye. Taurus is also home to the best-known supernova remnant, the Crab Nebula -- debris from a star that people saw explode in the year 1054.

Supernova explosions are destructive, but they also have their creative side. They forge a beautiful and precious element: gold.

Gold is precious because it's beautiful and rare. In fact, it's one of the rarest elements in the universe. That's because it's hard for the factories that forge all the elements -- the stars -- to make gold. During their long lives, stars normally manufacture elements no heavier than iron. But gold is much heavier.

Stars like the Sun don't make gold at all. Instead, gold is forged only in the heaviest stars -- and even then, only at the ends of their lives.

A massive star ends its life by exploding as a supernova. During the explosion, a huge number of neutrons -- particles that have no electric charge -- ram into atoms of iron from the star's core. In an act of cosmic alchemy, this bombardment transforms some of the iron into gold. So the gold in your wedding ring -- and all the other gold on Earth -- was born in the hearts of dying stars, and flung into the galaxy when they exploded.

But supernova explosions don't make a whole pot of gold. That's why gold is rare -- and precious.

Script by Ken Croswell, Copyright 2007

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