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planetary science
(Encyclopedia)planetary science or planetology, study of planets and planetary systems as a whole. Planetary science applies the theories and methods of traditional disciplines such as astronomy, geology, physics, ...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...gamma-ray astronomy
(Encyclopedia)gamma-ray astronomy, study of astronomical objects by analysis of the most energetic electromagnetic radiation they emit. Gamma rays are shorter in wavelength and hence more energetic than X rays (see...X-ray astronomy
(Encyclopedia)X-ray astronomy, study of celestial objects by means of the X rays they emit, in the wavelength range from 0.01 to 10 nanometers. X-ray astronomy dates to 1949 with the discovery that the sun emits X ...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 ...Periodic Table of the Elements: Mercury
(Encyclopedia)Periodic Table of the Elements: Mercury ...mercuric chloride
(Encyclopedia)mercuric chloride or mercury (II) chloride, chemical compound, HgCl2, a white powder of colorless rhombohedral crystals, somewhat soluble in water. It is also called bichloride of mercury or corrosive...amalgamation process
(Encyclopedia)amalgamation process əmălˌgəmāˈshən [key], in particular, a method to extract gold and silver from ores. The ore is crushed and treated with mercury, in which the metal dissolves. The amalgam i...In
(Encyclopedia)In, symbol for the element indium. ...perturbation
(Encyclopedia)perturbation pŭrˌtərbāˈshən [key], in astronomy and physics, small force or other influence that modifies the otherwise simple motion of some object. The term is also used for the effect produce...Browse by Subject
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