Radiation loosely refers to the travel of particles or energy in waves through a medium or space. There are two types of radiation: ionizing radiation and non-ionizing radiation. Light is a type of radiation. There are several practical uses for radiation, and different types of radiation can be either helpful or harmful. Nuclear radiation is well known as detrimental to health, but without light wave radiation, communications would be impossible. Radiation is integral to the world around us.


> Archaeological Sites and Collections

  • Regional Views: Report, images and archaeological data of all the regions.
  • Southeast Asia: A collection of Southeast Asian skeletal archaeological sites.
  • Greater Southwest: over 127,000 item documenting North America, South America and the Old World cultures.
  • Mesopotamia: Photographs of Mesopotamia archaeological sites.
  • Mesoamerica: A collection of Mesoamerica archaeological sites.

> History of Radiation


Wilhelm Rontgen observed and experimented with X-Rays while experimenting with vacuum tubes (glass tubes where there is no air or other matter present) in 1895. Researchers Marie & Pierre Curie, in 1899 coined the phrase “radioactivity” to describe whether an object emits radioactive waves, and also discovered that certain objects give off more radiation than others. In the early 1900s Earnest Rutherford, who is known for early models of the interior of an atom, distinguished between 3 types of radiation that he called positive, negative, and neutral radiation. Today these are known as Alpha, Beta, and Gamma, respectively.

  • The History of Radiation – This collection of links connects with volumes of information about radiation, and the history of its discovery.
  • Important Figures in the History of Radiation – This list contains biographies of people who played important roles in the discovery and understanding of radiation.
  • Wilhelm Rontgen – NASA discusses the advances in the knowledge of atoms by this famous physicist.
  • Marie Curie – Marie Curie made numerous contributions to the research of radiation, and discovered radium.
  • Peter Curie – Husband of Marie Curie, he worked with Marie Curie on several experiments involving radiation.
  • Ernest Rutherford – This biography details Ernest Rutherford’s discoveries regarding both atoms and radiation.
  • The Radium Water Jar – This article examines misunderstood applications of radium early in its history.
  • The History of Radiation – This article presents a really good summary of the discovery of radiation.

> Ionizing Radiation


There are two distinct types of radiation; ionizing and non-ionizing. Ionizing refers to the phenomena of radiation with high energy forcing electrons from their orbit around atoms, and thus ionizing them. There are many types of ionizing radiation, which includes Alpha, Beta, and Neutron radiation, as well as radiation like cosmic rays. Most ionizing radiation is dangerous to humans, especially if the exposure is long term.

  • Ionizing Radiation – This OSHA article discusses both what ionizing radiation is, as well as the health effects it can have on humans.
  • Radiation Safety – This article discusses the biological effects of ionizing radiation.
  • The Ionizing Radiation Fact Book – This book is practically an encyclopedia of the different types of ionizing radiation, as well as their effects on living things.

     Types of Ionizing Radiation

  • Alpha Radiation - Alpha radiation, or alpha decay, refers to radiation that is the result of an atom releasing neutrons or protons from its nucleus. Alpha radiation results from alpha decay, which is the most common form of cluster decay.
  • Beta Radiation- Beta Radiation, also known as beta decay, refers to radiation that is the result of an atom releasing electrons or positrons from its orbit. 
  • Gamma Radiation – Gamma refers to radiation involving photons; electromagnetic particles.
  • Neutron Radiation - Neutron Radiation is the result of nuclear fission, or nuclear fusion, as these cause free neutrons to be released from the center of an atom. Neutron radiation is the basis of nuclear fuel.
  • X-ray Radiation – X-Ray radiation occurs when electrons move between atoms. Usually this involves moving to atoms with lower atomic energy levels.

> Non-ionizing Radiation


Non-ionizing radiation does not have enough energy to knock electrons from their orbit. There are many types of non-ionizing radiation. Visible light waves are non-ionizing which is why visible light (unlike for instance ultra-violet light) is usually harmless to health. Micro waves, and radio waves are also non-ionizing. Generally ionizing radiation is considered harmful because it directly affects DNA. Non-ionizing radiation can be harmful for different reasons as well. These include through heat and electromagnetic fields, both of which have been shown to be harmful in certain situations.


     Types of Non-Ionizing Radiation

  • Visible Light Waves – This guide is a great, easy to understand, introduction to the facts about visible light waves.
  • Optical Radiation Protection – This article discusses situations where non-ionizing radiation can be harmful even though it does not affect DNA.
  • Electromagnetic Fields – This resource discusses the electromagnetic fields that can be generated by non-ionizing radiation.
  • Faraday Cages – This tutorial describes faraday cages, which can be used either intentionally or unintentionally to block non-ionizing radiation waves.
  • Measuring Non-ionizing Radiation – This guide describes ways to quantify non-ionizing radiation.
  • Magnetic Fields and Non-ionizing radiation – This guide discusses the effects of exposure to non-ionizing radiation, and magnetic fields.
  • Background Radiation – This resource helps you to identify how much non-ionizing radiation you are regularly exposing yourself to.
  • Mobile Phones & Your Health – How the non-ionizing radiation produced by the operation of cell phones can be a health concern.

> Electromagnetic Radiation


Electromagnetic radiation is any radiation produced by the movement of electrically charged particles. The electromagnetic spectrum is a special range of electromagnetic radiation, starting with radio waves, and ending in gamma waves. Infrared waves, microwaves, radio waves, as well as the visible spectrum of light waves, are all part of the spectrum of electromagnetic waves. Many forms of communication entail the use of electromagnetic waves. Radios, mobile phones, wireless Internet, remote controls; all of these require the use of electromagnetic radiation.


     Types of Electromagnetic Radiation

  • Infrared Radiation – An introduction to Infrared waves.
  • Microwaves – This article explains how microwaves are useful to communication, and differentiates them from the specific range of microwaves used to induce heat in objects.
  • Radiowaves – This article explains how radio waves work, and why they are used for communication.
  • Very Low Frequency Waves – Very Low Frequency (VLF) waves, one of the earliest used for communications, include waves like those used for long wave radios. 
  • Extremely Low Frequency Waves – Extremely Low Frequency waves (ELF), are produced by electric devices, and power lines, and basically anything that is using electrical current. These waves are the reason why radios often experience static when near power lines.
  • Thermal Radiation – Thermal Radiation refers to electromagnetic waves emitted by objects that experience heat.
  • Black Body Radiation – Black body radiation refers to the kind of electromagnetic radiation that can heat dark objects, like soot, causing them to heat up, but which passes through objects like glass.

> Uses of Radiation


Radiation and Communication

Numerous forms of communication rely on radioactive waves. Phone lines use electromagnetic radiation traveling across wires. Fiber optic lines use light waves traveling through specialized cabling. Radios use radio waves and one of two types of modulation to broadcast sound, or data. Cell phones use a special band of radio waves to send digital signals that encode data about sound, video, or data. Infrared remotes use infrared light to send information between devices. Microwaves can be used to send large amounts of data, at a high speed between two places. New technologies like Bluetooth, and WiFi both also use electrometric waves to transmit data. Some new technologies use very wide bands of electromagnetic radiation to send extremely large amounts of data quickly, with limited interference to other devices.


Radiation and Medicine

There are many types of waves that can be used in the field of medicine. One of the most well-known is X-Ray but there are others. Laser radiation is actually a type of electromagnetic radiation as well, and is used extensively in surgery. Radioactive treatments, like radioactive iodine, are used in the treatment of thyroid disorders like Graves disease. Over time the understanding of radiation has shown that some early medical uses of radiation, like radium water, were ill conceived and dangerous.


Radiation and Science

Radiation has a number of uses in science, aside simply from the study of radiation itself, which of course is a science in itself. Geiger counters are used in the study of earth movements, and use radioactive components. Certain elements emit different levels of radiation, or respond differently to radiation, so radiation is used in geology to study the makeup of different type of rocks, and rock formations. Carbon dating relies on the amount of radioactive carbon decay to determine the age of objects.

  • Radio Astronomy – How radio waves are used in the study of astrology to create color photos of distant parts of the cosmos with no use of lenses.
  • The Geiger Counter – How Geiger counters use radiation to detect radioactivity, and movement.
  • Uses of Radiation – A list of constructive ways radiation is used in science and other fields.
  • Ultraintense Lasers – How ultrafast, ultraintense lasers can be used in the sciences.
  • Radiation Emitting Devices – Several scientific applications for devices based on the use of radiation.
  • Spectrometry – Using light to determine the chemical properties of substances, including proteins.
  • Determining Moisture Content Using Microwaves – An overview of the theory behind how using microwaves can determine the moisture content of materials.

The History of X-Rays: A Complete Resource Guide