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The theory by which planetesimals are assumed to collide with one another and coalesce, eventually sweeping up enough material to form the planets.
Industry:Astronomy
A lens of two or more components with different refraction indices (e.g., crown glass and flint glass), used to correct for chromatic aberration.
Industry:Astronomy
Compensating for atmospheric distortions in a wavefront by high-speed changes in the shape of a small, thin mirror.
Industry:Astronomy
The slow rotation of the major axis of a planet's orbit in the same direction as the revolution of the planet itself, due to gravitational interactions with other planets and/or other effects (such as those due to general relativity.)
Industry:Astronomy
1) In Aristotelian physics, the fifth element, of which the stars and planets are made. 2) In Classical physics, an invisible medium that was thought to suffuse all space.
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Industry:Astronomy
Art of bringing parts of the universe to the perfect state toward which they were thought to aspire - e.g., gold for metals, immortality for human beings.
Industry:Astronomy
Element in the second column of the periodic table (from the left.)
Industry:Astronomy
Metal in the first column of the periodic table
Industry:Astronomy
1) Spontaneous emission by a heavier element (such as uranium) of positively charged helium nuclei - alpha particles - comprising 2 protons and 2 neutrons. The result of this radioactive decay is that the original element is very gradually converted into another element, with a decreased atomic number and mass. Alpha particle emission may be simultaneous with beta particle decay. 2) The disintegration of an atomic nucleus, in which the final products are an alpha particle and a nucleus with two fewer protons and two fewer neutrons than the original.
Industry:Astronomy
