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infrared astronomy

(Encyclopedia)infrared astronomy, study of celestial objects by means of the infrared radiation they emit, in the wavelength range from about 1 micrometer to about 1 millimeter. All objects, from trees and building...

Doppler effect

(Encyclopedia)Doppler effect, change in the wavelength (or frequency) of energy in the form of waves, e.g., sound or light, as a result of motion of either the source or the receiver of the waves; the effect is nam...

ultraviolet astronomy

(Encyclopedia)ultraviolet astronomy, study of celestial objects by means of the ultraviolet radiation they emit, in the wavelength range from about 90 to about 350 nanometers. Ultraviolet (UV) line spectrum measure...

echidna, in zoology

(Encyclopedia)echidna ĭkĭdˈnə [key] or spiny anteater, animal of the order Monotremata, the egg-laying mammals. A short-legged, grayish brown animal, the echidna is covered with sharp quills and can protect its...

Roman roads

(Encyclopedia)Roman roads, ancient system of highways linking Rome with its provinces. Their primary purpose was military, but they also were of great commercial importance and brought the distant provinces in touc...

poppy

(Encyclopedia)CE5 Greater celandine poppy, Chelidonium majus poppy, common name for some members of the Papaveraceae, a family composed chiefly of herbs of the Northern Hemisphere having a characteristic milky ...

dandelion

(Encyclopedia)dandelion [Eng. form of Fr.,=lion's tooth], any plant of the genus Taraxacum of the family Asteraceae (aster family), perennial herbs of wide distribution in temperate regions. The dandelion has a ros...

dark matter

(Encyclopedia)dark matter, material that is believed to make up nearly 27% of the mass of the universe but is not readily visible because it neither emits nor reflects electromagnetic radiation, such as light or ra...

star

(Encyclopedia)star, hot incandescent sphere of gas, held together by its own gravitation, and emitting light and other forms of electromagnetic radiation whose ultimate source is nuclear energy. The universe co...

dogbane

(Encyclopedia)dogbane, common name for some members of the Apocynaceae, a family of herbs, shrubs, and trees found in most parts of the world but especially in the tropics, where they are often climbing forms. Many...