Columbia Encyclopedia

Search results

500 results found

elongation

(Encyclopedia)elongation, in astronomy, the angular distance between two points in the sky as measured from a third point. The elongation of a planet is usually measured as the angular distance from the sun to the ...

astronomical unit

(Encyclopedia)astronomical unit (AU), mean distance between the earth and sun; one AU is c.92,960,000 mi (149,604,970 km). The astronomical unit is the principal unit of measurement within the solar system, e.g., M...

heliotrope

(Encyclopedia)heliotrope hēˈlēətrōpˌ [key] [Gr.,=sun-turning] or turnsole, name for any plant that turns to face the sun, especially members of the genus Heliotropium of the family Boraginaceae. The garden he...

Nippon

(Encyclopedia)Nippon nĭpˈŏn, nĭpŏnˈ [key], name for Japan, derived from Dai Nippon, meaning Great Japan. The expression comes from the Chinese ideograph for the place where the sun comes from, or Land of the ...

Braille

(Encyclopedia)Braille brāl [key], in astronomy, a small asteroid notable because it has the same atypical geologic composition as the larger asteroid Vesta. In 1999 the space probe Deep Space 1 passed within 16 mi...

phase, in astronomy

(Encyclopedia)CE5 Phases of the moon phase, in astronomy, the measure of how much of the illuminated surface of a planet or satellite can be seen from a point at a distance from that body; the term is most ofte...

escape velocity

(Encyclopedia)escape velocity, the velocity a body must be given in order to escape the gravitational hold of some other larger body, e.g., the earth, moon, or sun. A body given less than the escape velocity will f...

Day, Benjamin Henry

(Encyclopedia)Day, Benjamin Henry, 1810–89, American journalist. He learned the printer's trade in the office of the Springfield (Mass.) Republican and opened a printing office in New York City. Lack of work duri...

ephemeris time

(Encyclopedia)ephemeris time (ET), astronomical time defined by the orbital motions of the earth, moon, and planets. The earth does not rotate with uniform speed, so the solar day is an imprecise unit of time. Ephe...

Tropic of Capricorn

(Encyclopedia)Tropic of Capricorn, parallel of latitude at 23°30′ south of the equator; it is the southern boundary of the tropics. This parallel marks the farthest point south at which the sun can be seen direc...