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sextant

(Encyclopedia)CE5 Sextant sextant, instrument for measuring the altitude of the sun or another celestial body; such measurements can then be used to determine the observer's geographical position or for other n...

orientation

(Encyclopedia)orientation, in architecture, the disposition of the parts of a building with reference to the points of the compass. From remote antiquity the traditional belief in the efficacy of religious ceremoni...

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 ...

Antarctic Circle

(Encyclopedia)Antarctic Circle, imaginary circle on the surface of the earth at 661⁄2°S lat., i.e., 231⁄2° north of the South Pole. It marks the southernmost point at which the sun can be seen at the winter s...

Arctic Circle

(Encyclopedia)Arctic Circle, imaginary circle on the surface of the earth at 661⁄2°N latitude, i.e., 231⁄2° south of the North Pole. It marks the northernmost point at which the sun can be seen at the winter ...

Venus, in astronomy

(Encyclopedia)Venus, in astronomy, 2d planet from the sun; it is often called the evening star or morning star and is brighter than any object in the sky except the sun and the moon. Because its orbit lies between ...

latitude

(Encyclopedia)latitude, angular distance of any point on the surface of the earth north or south of the equator. The equator is latitude 0°, and the North Pole and South Pole are latitudes 90°N and 90°S, respect...

skin cancer

(Encyclopedia)skin cancer, malignant tumor of the skin. The most common types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma. Rarer forms include mycosis fungoides (a type of lymphom...

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...

Horrocks, Jeremiah

(Encyclopedia)Horrocks or Horrox, Jeremiah both: hŏrˈəks [key], 1618?–1641, English astronomer. He made the first observation of the transit of Venus. His Venus in sole visa, which narrates this experience, wa...