Columbia Encyclopedia
Search results
500 results found
radar
(Encyclopedia)radar, system or technique for detecting the position, movement, and nature of a remote object by means of radio waves reflected from its surface. Although most radar units use microwave frequencies, ...Copernican system
(Encyclopedia)Copernican system, first modern European theory of planetary motion that was heliocentric, i.e., that placed the sun motionless at the center of the solar system with all the planets, including the ea...solstice
(Encyclopedia)solstice sŏlˈstĭs [key] [Lat.,=sun stands still], in astronomy, either of the two points on the ecliptic that lie midway between the equinoxes (separated from them by an angular distance of 90°). ...Euripides
(Encyclopedia)Euripides yo͝orĭpˈĭdēz [key], 480 or 485–406 b.c., Greek tragic dramatist, ranking with Aeschylus and Sophocles. Born in Attica, he lived in Athens most of his life, though he spent much time o...Sophocles
(Encyclopedia)Sophocles sŏfˈəklēz [key], c.496 b.c.–406 b.c., Greek tragic dramatist, younger contemporary of Aeschylus and older contemporary of Euripides, b. Colonus, near Athens. A man of wealth, charm, an...Sagan, Carl Edward
(Encyclopedia)Sagan, Carl Edward sāˈgən [key], 1934–96, American astronomer and popularizer of science, b. New York City. Early in his career he investigated radio emissions from Venus and concluded that the c...Struve
(Encyclopedia)Struve shtro͞oˈvə [key], family of astronomers. Friedrich Georg Wilhelm von Struve, 1793–1864, was born in Germany but later lived in Russia. While director (1817–39) of Dorpat Observatory he w...Theseus
(Encyclopedia)Theseus thēˈsyo͞os, –sēəs [key], in Greek mythology, hero of Athens; son of either King Aegeus or Poseidon. Before Aegeus left Troezen he placed his sword and sandals beneath a huge rock and to...revolution
(Encyclopedia)revolution, in a political sense, fundamental and violent change in the values, political institutions, social structure, leadership, and policies of a society. The totality of change implicit in this...zero
(Encyclopedia)zero, that number which, when added to any number, leaves the latter unchanged; its symbol is 0. The introduction of zero into the decimal system was the most significant achievement in the developmen...Browse by Subject
- Earth and the Environment +-
- History +-
- Literature and the Arts +-
- Medicine +-
- People +-
- Philosophy and Religion +-
-
Places
+-
- Africa
- Asia
- Australia and Oceania
- Britain, Ireland, France, and the Low Countries
- Commonwealth of Independent States and the Baltic Nations
- Germany, Scandinavia, and Central Europe
- Latin America and the Caribbean
- Oceans, Continents, and Polar Regions
- Spain, Portugal, Italy, Greece, and the Balkans
- United States, Canada, and Greenland
- Plants and Animals +-
- Science and Technology +-
- Social Sciences and the Law +-
- Sports and Everyday Life +-
