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transit
(Encyclopedia)transit, in astronomy, passage of a body across a meridian or passage of a small body across the visible disk of a larger one. (The passage of a large body across a smaller one is called an eclipse or...second
(Encyclopedia)second, abbr. sec or s, fundamental unit of time in all systems of measurement. In practical terms, the second is 1/60 of a minute, 1/3,600 of an hour, or 1/86,400 of a day. Since the length of the da...corona, in astronomy
(Encyclopedia)corona, luminous envelope surrounding the sun, outside the chromosphere. Its density is less than one billionth that of the earth's atmosphere. The corona is visible only at the time of totality durin...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 ...Eudoxus of Cnidus
(Encyclopedia)Eudoxus of Cnidus yo͞odŏkˈsəs, nīˈdəs [key], 408?–355? b.c., Greek astronomer, mathematician, and physician. From the accounts of various ancient writers, he appears to have studied with Plat...midsummer day and midsummer night
(Encyclopedia)midsummer day and midsummer night, names given to the feast of the nativity of St. John the Baptist (June 24) and the preceding night (St. John's Eve, June 23). Because midsummer is about the time of ...solar energy
(Encyclopedia)solar energy, any form of energy radiated by the sun, including light, radio waves, and X rays, although the term usually refers to the visible light of the sun. Solar energy is needed by green plants...De la Rue, Warren
(Encyclopedia)De la Rue, Warren dĕlˈəro͞o, dĕləro͞oˈ [key], 1815–89, British scientist and inventor. Especially noted as an astronomer, he was a pioneer in celestial photography. He adapted the wet-plate ...chromosphere
(Encyclopedia)chromosphere krōˈməsfērˌ [key] [Gr.,=color sphere], layer of rarefied, transparent gases in the solar atmosphere; it measures 6,000 mi (9,700 km) in thickness and lies between the photosphere (th...solar plexus
(Encyclopedia)solar plexus, dense cluster of nerve cells and supporting tissue, located behind the stomach in the region of the celiac artery just below the diaphragm. It is also known as the celiac plexus. Rich in...Browse by Subject
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