Children's birthday parties and big-time sports events have a lot in common. They're loud, they're more expensive every year, and they usually feature colorful bags of helium floating through the sky -- balloons and blimps.
Helium is rare on Earth. But another big gas bag that floats across the sky has lots of it: the Sun. In fact, scientists discovered it in the Sun years before they found it here on Earth. So they named it "helium" after the Greek name for the Sun, "Helios."
Helium is the "ash" produced by nuclear reactions in the Sun's core.
Most of the core consists of hydrogen -- the lightest and simplest chemical element. The core's extreme heat strips electrons away from the hydrogen atoms, leaving only bare protons.
The protons have a positive electric charge, so they tend to repel each other -- just like the positive poles of two magnets. But in the superhot core, they're moving so fast that they sometimes ram into each and stick together -- a process known as fusion. When that happens, they form helium.
Today, the Sun converts about 600 million tons of hydrogen to helium every second. About four million tons of hydrogen is converted to energy -- and that's what makes the Sun shine.
Despite the staggering numbers, the Sun won't run out of hydrogen anytime soon. It's so huge that it'll continue to manufacture helium for several billion years longer -- enough helium to float quite a few balloons.
Script by Damond Benningfield, Copyright 2009
For more skywatching tips, astronomy news, and much more, read StarDate magazine.