Clasificación de la Biblioteca del CongresoQB44.2

16th century(179) 17th century(307) academic(108) aliens(243) asteroids(68) astrobiology(252) astrology(391) astrophysics(680) biographies(152) biography(3,241) biology(308) black holes(118) children(365) children's(499) cosmology(1,636) cosmos(163) earth(270) education(168) educational(69) Europe(116) evolution(164) experiments(74) exploration(86) extraterrestrial(53) Extraterrestrials(173) galaxies(247) galaxy(82) Galileo(905) general science(66) geography(145) gravity(43) guide(318) guidebook(106) history(3,483) history of ideas(61) history of science(1,773) how-to(97) informational(147) inventors(61) Isaac Newton(32) Italy(377) Jupiter(64) juvenile(178) juvenile non-fiction(104) kids(127) maps(125) Mars(111) math(475) meteors(47) moon(473) nasa(65) natural science(344) nature(572) observation(145) outer space(340) philosophy of science(115) photographs(97) photography(306) physics/astronomy(44) picture book(564) planet(68) planets(1,575) Pluto(44) popular science(477) quasars(28) reference(1,993) reference guide(28) religion(285) Renaissance(307) rockets(46) science(16,512) science and technology(123) science biography(43) science nonfiction(63) scientific instruments(19) scientific revolution(55) scientists(333) solar system(1,141) space exploration(269) space flight(50) stars(2,050) time(91) universe(790)