Radiation

Radiation is energy that travels through space in waves or tiny particles. It is all around you, all the time. Sunlight is radiation. The heat from a campfire is radiation. So are X-rays, microwaves, and radio signals. Most radiation is harmless in small amounts. Some kinds can be dangerous if you get too much.

Scientists sort radiation into two main groups. The first is called non-ionizing radiation. It is the weaker kind. Visible light, radio waves, microwaves, and the warmth you feel from the sun all fit here. This radiation can heat things up, but it does not damage the tiny atoms inside your body.

The second group is called ionizing radiation. It carries enough energy to knock pieces off of atoms. X-rays, gamma rays, and the particles that shoot out of uranium all belong to this group. In small doses, this kind of radiation is useful. Doctors use X-rays to see broken bones. In large doses, it can hurt living cells and even cause cancer.

Some materials give off ionizing radiation on their own. This is called being radioactive. Uranium, radon gas, and a few other elements have atoms that are unstable. They slowly break apart and release energy. The French scientist Marie Curie discovered two new radioactive elements in the late 1800s. Her research won two Nobel Prizes. It also made her very sick. Nobody knew yet how dangerous the work was.

You get small amounts of radiation every day from natural sources. Rocks, soil, food, and even your own body give off tiny bits of it. Flying in an airplane raises the dose a little, because there is less air above you to block radiation from space. A single chest X-ray gives you about the same amount of radiation as ten days of normal life on the ground.

Radiation can also be very useful. Power plants use the energy from splitting uranium atoms to make electricity. Doctors use strong beams of radiation to shrink cancer tumors. Smoke detectors use a tiny radioactive source to sense smoke in the air. Spacecraft use radiation from the sun to charge their batteries.

When a nuclear power plant has an accident, ionizing radiation can spread far from the site. The Chernobyl accident in 1986 forced more than 100,000 people to leave their homes in Ukraine. Parts of the area around Chernobyl are still too radioactive for people to live in today, almost 40 years later.