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Dione, in astronomy

(Encyclopedia)Dione dīōˈnē [key], in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn IV (or S4), Dione is 695 mi (1,120 km) in diameter, orbits Saturn at a mean distanc...

crossing over

(Encyclopedia)crossing over, process in genetics by which the two chromosomes of a homologous pair exchange equal segments with each other. Crossing over occurs in the first division of meiosis. At that stage each ...

Enceladus

(Encyclopedia)Enceladus ĕnsĕlˈədəs [key], in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn II (or S2), Enceladus is 310 mi (500 km) in diameter, orbits Saturn at a m...

altitude

(Encyclopedia)altitude, vertical distance of an object above some datum plane, such as mean sea level or a reference point on the earth's surface. It is usually measured by the reduction in atmospheric pressure wit...

Golden Section

(Encyclopedia)CE5 Rectangle ABCD is a golden rectangle. Removing the square AEFD leaves the rectangle EBCF Golden Section, in mathematics, division of a line segment into two segments such that the ratio of the...

Janus, in astronomy

(Encyclopedia)Janus jāˈnəs [key], in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn X (or S10), Janus is an irregularly shaped (nonspherical) body measuring about 122 m...

Academy

(Encyclopedia)Academy, school founded by Plato near Athens c.387 b.c. It took its name from the garden (named for the hero Academus) in which it was located. Plato's followers met there for nine centuries until, al...

Tethys , in astronomy

(Encyclopedia)Tethys tēˈthĭs [key], in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn III (or S3), Tethys is 659 mi (1060 km) in diameter, orbits Saturn at a mean dista...

Trinity , doctrine in Christianity

(Encyclopedia)Trinity [Lat.,=threefoldness], fundamental doctrine in Christianity, by which God is considered as existing in three persons. While the doctrine is not explicitly taught in the New Testament, early Ch...

radical, in chemistry

(Encyclopedia)radical, in chemistry, group of atoms that are joined together in some particular spatial structure and that take part in most chemical reactions as a single unit. Important inorganic radicals include...