More Moon and Jupiter
Ordinary elements can do some extraordinary things deep inside Jupiter and Saturn, the largest planets in the solar system. Hydrogen and helium may be squeezed so tightly that they form metals. And the two of them may blend together to form an odd alloy -- one that generates strong electric currents, which in turn produce magnetic fields that surround the planets.
Jupiter is the larger and more massive of the two planets. It has a small, dense core surrounded by thick layers of hydrogen and helium. The planet's gravity squeezes the hydrogen and helium like a blob of Silly Putty caught in a vise grip. The pressure may be up to a hundred million times greater than the air pressure at Earth's surface.
Experiments have shown that under these conditions, the hydrogen around the core forms a liquid metal. It spins at a different rate from the solid core, producing a dynamo effect -- like an electric generator. And that produces the planet's strong magnetic field.
More recent experiments have shown that the same thing may happen to the helium. And mathematical models suggest that the hydrogen and helium may mix together, forming a layer of liquid metal that's thousands of miles thick.
Look for Jupiter just barely to the upper right of the Moon this evening. It looks like a brilliant cream-colored star. We can't see inside Jupiter, but we know that some extraordinary things are happening deep inside this giant planet.
Script by Damond Benningfield, Copyright 2008
For more skywatching tips, astronomy news, and much more, read StarDate magazine.