This is the international symbol for radiation. It is often used to indicate that radioactive materials are stored nearby.
Click on image for full size
Original artwork by Windows to the Universe staff.
Some materials give off radiation. We say that those substances are "radioactive". Radioactive materials are often, though not always, hazardous to living things.
There are many different types of radioactive materials. Some emit particle radiation, like alpha or beta particles or neutron radiation. Some give off electromagnetic radiation, such as gamma rays or X-rays.
Most elements come in various "versions", called isotopes, with different numbers of neutrons and slightly differing properties. In many cases, less-common isotopes of common substances are radioactive. For example, the rare isotope of carbon called carbon-14 is radioactive. It has 8 neutrons (instead of the usual 6) and radiates beta particles. When they emit radiation, radioactive substances undergo radioactive decay. The element may be transformed from one isotope to another, or may become a different element altogether. When carbon-14 decays by emitting a beta particle, it becomes nitrogen-14. Isotopes that do not decay are said to be "stable".
Radioactive isotopes can be dangerous to living things and damaging to equipment such as electronics. The level of danger depends, however, on the amount of radioactive substance present and the type of radiation and the rate of decay. Radioactive materials exist (mostly in trace quantities) in nature all around us. Small enough doses of most types of radiation cause us little harm.
Humans make use of radioactive materials in many ways. We use them in medicine to "label" and detect certain substances or tissues. We use them to determine the ages of artifacts via radiocarbon (carbon-14) dating. We also use them for nuclear power and in nuclear weapons.
Shop Windows to the Universe Science Store!
Learn about Earth and space science, and have fun while doing it! The games
section of our online store
includes a climate change card game
and the Traveling Nitrogen game
You might also be interested in:
Radiation comes in two basic types: electromagnetic radiation transmitted by photons, and particle radiation consisting of electrons, protons, alpha particles, and so forth. Electromagnetic radiation,...more
Radiation can be harmful to living creatures. Radiation can harm living things directly by damaging their cells. The cells might stop functioning, or they might be unable to reproduce. Radiation can also...more
One main type of radiation, particle radiation, is the result of subatomic particles hurtling at tremendous speeds. Protons, cosmic rays, and alpha and beta particles are some of the most common types...more
Electromagnetic radiation is the result of oscillating electric and magnetic fields. The wave of energy generated by such vibrations moves through space at the speed of light. And well it should... for...more
An element (also called a "chemical element") is a substance made up entirely of atoms having the same atomic number; that is, all of the atoms have the same number of protons. Hydrogen, helium, oxygen,...more
Isotopes are different "versions" of a chemical element. All atoms of an element have the same number of protons. For example, all hydrogen atoms have one proton, all carbon atoms have six protons, and...more
Carbon-14 is an isotope of the element carbon. All carbon atoms have 6 protons in their nucleus. Most carbon atoms also have 6 neutrons, giving them an atomic mass of 12 ( = 6 protons + 6 neutrons). Carbon-14...more