gravity-collapse structure
21Stellar evolution — Life cycle of a Sun like star Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only a few million years (for the most… …
22Antarctica — /ant ahrk ti keuh, ahr ti /, n. the continent surrounding the South Pole: almost entirely covered by an ice sheet. ab. 5,000,000 sq. mi. (12,950,000 sq. km). Also called Antarctic Continent. * * * Antarctica Introduction Antarctica Background:… …
23Russia — /rush euh/, n. 1. Also called Russian Empire. Russian, Rossiya. a former empire in E Europe and N and W Asia: overthrown by the Russian Revolution 1917. Cap.: St. Petersburg (1703 1917). 2. See Union of Soviet Socialist Republics. 3. See Russian… …
24United States — a republic in the N Western Hemisphere comprising 48 conterminous states, the District of Columbia, and Alaska in North America, and Hawaii in the N Pacific. 267,954,767; conterminous United States, 3,022,387 sq. mi. (7,827,982 sq. km); with… …
25building construction — Techniques and industry involved in the assembly and erection of structures. Early humans built primarily for shelter, using simple methods. Building materials came from the land, and fabrication was dictated by the limits of the materials and… …
26Neutron star — redirects here. For the story by Larry Niven, see Neutron Star (short story). Neutron stars crush half a million times more mass than Earth into a sphere no larger than Manhattan. A neutron star is a type of stellar remnant that can result from… …
27Planet — This article is about the astronomical object. For other uses, see Planet (disambiguation) …
28White dwarf — For other uses, see White dwarf (disambiguation). Image of Sirius A and Sirius B taken by the Hubble Space Telescope. Sirius B, which is a white dwarf, can be seen as a faint pinprick of light to the lower left of the much brighter Sirius A …
29Impact crater — The prominent impact crater Tycho on the Moon. In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body. In most common usage,… …
30Many-worlds interpretation — The quantum mechanical Schrödinger s cat paradox according to the many worlds interpretation. In this interpretation every event is a branch point; the cat is both alive and dead, even before the box is opened, but the alive and dead cats are in… …
