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digital radio

(Encyclopedia)digital radio, audio broadcasting in which an analog audio signal is converted into a digital signal before being transmitted; also known as digital audio broadcasting (DAB) and high-definition radio....

day

(Encyclopedia)day, period of time for the earth to rotate once on its axis. The ordinary day, or solar day, is measured relative to the sun, being the time between successive passages of the sun over a stationary o...

Alpha Centauri

(Encyclopedia)Alpha Centauri ălˈfə sĕntôrˈē [key], brightest star in the constellation Centaurus and 3d-brightest star in the sky; also known as Rigil Kent or Rigil Kentaurus; 1992 position R.A. 14h39.1m, De...

Jaspers, Karl

(Encyclopedia)Jaspers, Karl kärl yäsˈpərs [key], 1883–1969, German philosopher and psychopathologist, b. Oldenburg. After receiving his medical degree (1909) he became (1914) lecturer in psychology and in 192...

solar system

(Encyclopedia)CE5 Solar system CE5 solar system, the sun and the surrounding planets, natural satellites, dwarf planets, asteroids, meteoroids, and comets that are bound by its gravity. The sun is by far the ...

astronaut

(Encyclopedia)astronaut, crew member on a U.S. manned spaceflight mission; the Soviet term is cosmonaut. Candidates for manned spaceflight are carefully screened to meet the highest physical and mental standards, a...

acceleration

(Encyclopedia)acceleration, change in the velocity of a body with respect to time. Since velocity is a vector quantity, involving both magnitude and direction, acceleration is also a vector. In order to produce an ...

Kuiper, Gerard Peter

(Encyclopedia)Kuiper, Gerard Peter or Gerrit Pieter gĕrˈĭt pēˈtər kīˈpər [key], 1905–73, American astronomer, b. the Netherlands. Kuiper is considered to be the father of modern planetary science for his...

universal time

(Encyclopedia)universal time (UT), the international time standard common to every place in the world, it nominally reflects the mean solar time along the earth's prime meridian (renumbered to equate to civil time)...

seasons

(Encyclopedia)CE5 The seasons are caused by the tilt of the earth's axis to the plane of its orbit about the sun. The Northern Hemisphere is tilted toward the sun in the summer and receives more direct rays than...