magnetic field

Desert ants spend the first four weeks of their lives in their underground nest. They keep themselves busy by digging tunnels, building chambers, and doing general maintenance inside.

The Earth needed a number of things to become habitable. First of all, it needed to be close to a star, but not too close. It also needed water, a rocky surface and atmosphere. Most important of all, however, it needed a magnetic field.

Go to the hospital to have a doctor check out an internal problem and you're liable to hear about MRI scans, CT scans and PET scans. All of these scans take detailed pictures of your body's insides.

Do you ever think about the risks the Apollo astronauts took in the name of science? It's amazing. Actually, the astronauts were at risk of something many people don't know about: the Sun.

The Northern Lights, also known as the Aurora Borealis, are waving ribbons of green, red and purple in the sky. These curtains of light can be seen as far south as the South Pole. In the southern hemisphere, however, they're called the Aurora Australis. They can also sometimes be seen in New Zealand or Chile.