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Mars, in astronomy

(Encyclopedia)Mars, in astronomy, 4th planet from the sun, with an orbit next in order beyond that of the earth. Mars has two natural satellites, discovered by Asaph Hall in 1877. The innermost of these, Phobos...

Cretaceous period

(Encyclopedia)Cretaceous period krĭtāˈshəs [key], third and last period of the Mesozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table), lasting from approximately 144 to 65 millio...

Chordata

(Encyclopedia)CE5 Common features in representative groups of the phylum Chordata Chordata kôrdāˈtə, –däˈ– [key], phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal ...

contemporary art

(Encyclopedia)contemporary art, the art of the late 20th cent. and early 21st cent., both an outgrowth and a rejection of modern art. As the force and vigor of abstract expressionism diminished, new artistic moveme...

geography

(Encyclopedia)geography, the science of place, i.e., the study of the surface of the earth, the location and distribution of its physical and cultural features, the areal patterns or places that they form, and the ...

Persian Gulf Wars

(Encyclopedia)Persian Gulf Wars, two conflicts involving Iraq and U.S.-led coalitions in the late 20th and early 21st cent. The First Persian Gulf War, also known as the Gulf War, Jan.–Feb., 1991, was an armed co...

ocean

(Encyclopedia)ocean, interconnected mass of saltwater covering 70.78% of the surface of the earth, often called the world ocean. It is subdivided into four (or five) major units that are separated from each other i...

transplantation, medical

(Encyclopedia)transplantation, medical, surgical procedure by which a tissue or organ is removed and replaced by a corresponding part, usually from another part of the body or from another individual. A life-saving...

Guinea-Bissau

(Encyclopedia)CE5 Guinea-Bissau bĭsˌsouˈ [key], officially Republic of Guinea-Bissau, republic (2015 est. pop. 1,771,000), 13,948 sq mi (36,125 sq km), W Africa. It borders on the Atlantic Ocean in the west, ...

insect

(Encyclopedia)CE5 External anatomy of a female grasshopper, representative of the class Insecta insect, invertebrate animal of the class Insecta of the phylum Arthropoda. Like other arthropods, an insect has a ...