Energy transmitted through space as waves or particles.

1. Rays of energy including gamma rays and X-rays which are just two of the types of energy waves often used in medicine.
2. The use of energy waves that diagnose or treat disease.

Differentiation of related organisms by adaptation to dissimilar environments or modes of living (as horses, wolves, seals, and whales, and all mammals).

The process of evolution by which species multiply, diverge into different niches; for example, species that are predators on different kinds of prey, and come to occupy the same or at least overlapping ranges.

The invasion, through time, of a wide diversity of adaptive zones and niches by a group of organisms undergoing evolutionary diversification.

Electromagnetic radiation left over from the original formation of the univiverse in the Big Bang.

Streams of high-energy particles from outer space, consisting of protons, alpha particles, and light nuclei, which collide with atomic nuclei in the earth's atmosphere, and produce secondary nuclear particles; primarily mesons (elementary particles responsible for the forces in the atomic nucleus); such as, pions and muons (types of subatomic particles), that shower the earth.

Radiation received from the sun after reflection and scattering by the atmosphere and ground.

Radiation received by direct solar rays.

Measured by a pyrheliometer with a solar aperture of 5.7 degrees to transcribe the solar disc.

Waves of energy which consist of a combination of electric and magnetic fields at right angles to each other.

Such radiation results commonly from the acceleration of an electric charge, and is propagated in a vacuum at the speed of light.

Electromagnetic radiation with wavelengths shorter than those of X-rays.

1. Electromagnetic radiation whose wavelengths lie in the range from 0.75 micrometer to 1000 micrometers; invisible long wavelength radiation (heat) capable of producing a thermal or photovoltaic effect, though less effective than visible light.
2. The part of the electromagnetic spectrum that lies between the microwave and visible wavelengths.

On either side of the band of visible radiation are electromagnetic radiations which are invisible, but which can nevertheless be perceived.

People know about the stars because they can be seen and because of this, optical telescopes are the traditional instruments of astronomy; however, it must not be forgotten that light is only one form of electromagnetic radiation, and that it forms only a narrow band in the electromagnetic spectrum.

The radiation which fills the universe uniformly in all directions, with a peak intensitiy at about one millimeter wavelength in the microwave region.

It is interpreted in the "big bang theory" as the remnant of the initial explosion.

A form of electromagnetic radiation emitted by an electric charge moving relativistically through a magnetic field.

It is characterized by being polarized.

The common name given to radio waves emitted at 1,420 megahertz as the result of the "flipping over" of the electron in a hydrogen atom in order to oppose the spin direction of the central proton.

The radiation is an example of line emission.

1. Two zones of charged particles around the earth's magnetosphere, discovered in 1958 by U.S. physicist Jame Van Allen.

The atomic particles came from the earth's upper atmosphere and the solar wind, and are trapped by the earth's magnetic field.

The inner belt lies above the equator, and contains protons and electrons from the solar wind.

2. One of two regions, lying at about 1,900 miles, 3,000 kilometers, and 12,500 miles, 20,000 kilometers, above the equator, in which charged particles, trapped in the earth's magnetosphere, oscillate between the magnetic poles.

The particles are caught from the solar wind or produced by collisions between air molecules and cosmic rays.