Encyclopedia of Astronomy & Astrophysics
eBook - ePub

Encyclopedia of Astronomy & Astrophysics

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eBook - ePub

Encyclopedia of Astronomy & Astrophysics

About this book

In a unique collaboration, Nature Publishing Group and Institute of Physics Publishing have published the most extensive and comprehensive reference work in astronomy and astrophysics. This unique resource covers the entire field of astronomy and astrophysics and this online version includes the full text of over 2, 750 articles, plus sophisticated search and retrieval functionality and links to the primary literature.

The Encyclopaedia's authority is assured by editorial and advisory boards drawn from the world's foremost astronomers and astrophysicists. This first class resource is an essential source of information for undergraduates, graduate students, researchers and seasoned professionals, as well as for committed amateurs, librarians and lay people wishing to consult the definitive astronomy and astrophysics reference work.

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Information

Publisher
CRC Press
Year
2001
Edition
1
eBook ISBN
9781000523096

Table of contents

  1. Cover
  2. Half-Title Page
  3. Title Page
  4. Copyright Page
  5. Table of Contents
  6. 61 Cygni
  7. Abastumani Astrophysical Observatory
  8. Abbe, Ernst (1840–1905)
  9. Abbott, Francis (1799–1883)
  10. Abell Clusters
  11. Aberration
  12. Abetti, Antonio (1846–1928) and Abetti, Giorgio (1882–1982)
  13. Absolute Zero
  14. Absorption Spectrum
  15. Abul Wafa Mohammad al-Buzjani (940–97)
  16. Acceleration
  17. Accretion
  18. Accretion Disks
  19. Ace (Advanced Composition Explorer)
  20. Achernar
  21. Achilles
  22. Achondrite
  23. Acousto-Optic Spectrographs
  24. Active Galactic Nuclei: Variability
  25. Active Galactic Nucleus
  26. Active Galaxies: Observations
  27. Active Galaxies: Observing their Variability by Amateurs
  28. Active Galaxies: Overview
  29. Active Galaxies: Unified Model
  30. Active Galaxy
  31. Active Optics
  32. Active Region
  33. Adams, John Couch (1819–92)
  34. Adams, Walter Sydney (1876–1956)
  35. Adaptive Optics
  36. Adelard of Bath (1075–1160)
  37. Aepinus, Franz Ulrich Theodosius (1724–1802)
  38. Aerolite
  39. Aglaonike (с. 200 ĐČс)
  40. Air Force Maui Optical Station
  41. Airglow
  42. Airy Disk
  43. Airy, Sir George Biddell (1801–92)
  44. Aitken, Robert Grant (1864–1951)
  45. Akebono (EXOS-D)
  46. al-Battani, Abu Abdullah [known as Albategnius] (c. 868–c. 929)
  47. al-Biruni, Abu Raihan (973–1048)
  48. al-Farghani, Abu’I-Abbas Ahmad ibn Muhammad ibn Kathir (c. 860)
  49. al-Khwarizmi [al-Khawarizmi; aÄŸKhwarizmi], Abu Abd-Allah [Abdullah; Ja’far] Mohammad [Muhammad] ibn Musa [Bin Musa] (с. 800–c. 850)
  50. al-Quhi, Abu Sahl Wayjan ibn Rustam (c. 940–c. 1000)
  51. al-Sufi, Abu al-Rahman (903–86)
  52. al-Zarqali [known as Azarchiel, Azaquiel, Azachel or As Sarkali] (around 1080)
  53. Albedo
  54. Albireo
  55. Albumazar [Abu Mashar al-Balkhi; Abu-Mashar; Abu Maschar] (787–885)
  56. Aldebaran
  57. Aldrin, Edwin Eugene, Jr [‘Buzz’] (1930–)
  58. Alexis (Array of Low Energy X-ray Imaging Sensors)
  59. Alfonso X [Alfonso X of Castile; Alfonso the Astronomer; Alfonso the Wise] (1221–84)
  60. AlfvĂ©n, Hannes Olof Gösta (1908–95)
  61. Algol
  62. Algonquin Radio Observatory
  63. Allegheny Observatory
  64. Allen, Clabon [‘Clay’] Walter (1904–87)
  65. Allen, David (1946–94)
  66. Allende Meteorite
  67. Almanac
  68. Alpha Centauri
  69. Alpha Centauri A+B
  70. Alpha Particle
  71. Alpher, Ralph Asher (1921–)
  72. Altair
  73. Altazimuth Mounting
  74. Altitude
  75. Alvarez, Luis Walter (1911–88)
  76. AM Herculis
  77. Amateur Astronomical Societies
  78. Amateur Spectroscopy
  79. Amateur–Professional Collaboration in Astronomy
  80. Ambartsumian [Ambarzumjan], Viktor Amazaspovich (1908–96)
  81. American Association of Variable Star Observers
  82. American Astronomical Society (AAS)
  83. Anaxagoras of Clazomenae (c. 500–c. 428 ВС)
  84. Anaximander of Miletus (c. 611–c. 547 BC)
  85. Anaximenes of Miletus (c. 585–c. 525 BC)
  86. Anderson, Carl David (1905–91)
  87. Andromeda
  88. Andromeda Galaxy
  89. Anglo-Australian Observatory
  90. Angstrom
  91. Ångström, Anders Jonas (1814–74)
  92. Angular Momentum
  93. Anomalous Cosmic Rays
  94. Anomaly
  95. Antapex
  96. Antares
  97. Anthelme, Voituret (с. 1618–83)
  98. Anthropic Principle
  99. Antimatter
  100. Antlia
  101. Antoniadi, Eugenios (1870–1944)
  102. Apache Point Observatory
  103. Apastron
  104. Aperture
  105. Aperture Synthesis
  106. Apex
  107. Aphelion
  108. Aphrodite Terra
  109. Apian [Bienewitz or Bennewitz], Peter (1495–1552)
  110. Apoapsis
  111. Apogee
  112. Apollo
  113. Apollonius [Apollonios] of Perga (200–100 BC)
  114. Apparent Solar Time
  115. Apparition
  116. Appleton, Edward Victor (1892–1965)
  117. Appulse
  118. Apus
  119. Aquarius
  120. Aquila
  121. Ara
  122. Arago, Dominique François Jean (1786–1853)
  123. Aratus [Aratos] (c. 315–c. 245 BC)
  124. Arcetri Astrophysical Observatory
  125. Archelaus (fifth century BC)
  126. Archimedes of Syracuse (287–212 BC)
  127. Arcturus
  128. Arecibo Observatory
  129. Argelander, Friedrich Wilhelm August (1799–1875)
  130. Argo Navis
  131. Ariel
  132. Ariel
  133. Aries
  134. Aristarchus of Samos (310–230 BC)
  135. Aristillus (c. 200 BC)
  136. Aristotle of Stagira (384–322 BC)
  137. Armagh Observatory
  138. Armillary Sphere
  139. Armstrong, Neil Alden (1930–)
  140. Arrhenius, Svante August (1859–1927)
  141. Art and Literature
  142. Artificial Satellite
  143. ASCA (Advanced Satellite for Cosmology and Astrophysics/Astro-D)
  144. Ashen Light
  145. Association of Universities for Research in Astronomy
  146. Asterism
  147. Asteroid Belt
  148. Asteroid Discovery in History
  149. Asteroids
  150. Astigmatism
  151. Astrid
  152. Astro
  153. Astro
  154. Astro Space Center, Moscow
  155. Astrochemistry
  156. Astrodynamics
  157. Astrolabe
  158. Astrology
  159. Astrometric Surveys
  160. Astrometry
  161. Astrometry with Hubble Space Telescope
  162. Astrometry: History
  163. Astrometry: Telescopes and Techniques
  164. Astron
  165. Astronomical Institute of Athens
  166. Astronomical Observing Notebooks for Amateurs
  167. Astronomical Photography by Amateurs with Telescopes
  168. Astronomical Societies and Publications
  169. Astronomical Society of Australia
  170. Astronomical Society of the Pacific
  171. Astronomical Spectroscopy
  172. Astronomical Unit
  173. Astronomical Wide-field CCD Imaging by Amateurs
  174. Astronomische Gesellschaft
  175. Astronomische Nederlands Satelliet (ANS)
  176. Astronomisches Institut der UniversitĂ€t WĂŒrzburg
  177. Astronomy
  178. Astronomy and Astrophysics in India
  179. Astronomy on the Web
  180. Astrophysical Bounds on Particle Properties
  181. Astrophysical Institute, Potsdam
  182. Astrophysical Jets
  183. Astrophysics
  184. Astrophysics to 1900
  185. Atacama Large Millimeter Array
  186. Atmospheric Pressure
  187. Atmospheric refraction
  188. Atom
  189. Aureole
  190. Auriga
  191. Aurora
  192. Aurorae: Observing by Amateurs
  193. Auroral Kilometric Radiation
  194. Australia Telescope National Facility
  195. Australian Astronomy
  196. Auzout, Adrien (1622-91)
  197. Axis (pl: axes)
  198. Azimuth
  199. Baade, Wilhelm Heinrich Walter (1893–1960)
  200. Babbage, Charles (1792–1871)
  201. Babcock, Harold Delos (1882–1968) and Babcock, Horace Welcome (1912–)
  202. Babylonian Astronomy
  203. Backlund, Jöns Oskar (1846–1916)
  204. Baffin, William (c 1584–1622)
  205. Bailey, Solon Irving (1854–1931)
  206. Baillaud, Édouard Benjamin (1848–1934)
  207. Bailly, Jean Sylvain (1736–93)
  208. Baily, Francis (1774-1844)
  209. Baily’s Beads
  210. Ball, Sir Robert Stawell (1840–1913)
  211. Balmer, Johann Jakob (1825–98)
  212. Banneker, Benjamin (1731–1806)
  213. Bappu, Manali Kallat Vainu (1927–82)
  214. Barlow Lens
  215. Barlow, Peter (1776–1862)
  216. Barnard, Edward Emerson (1857–1923)
  217. Barnard’s Loop (Sh2-276)
  218. Barnard’s Star
  219. Barred Spiral Galaxy
  220. Barringer, Daniel Moreau (1860–1929)
  221. Barycenter
  222. Baryogenesis (baryon genesis or matter/antimatter asymmetry)
  223. Baryons
  224. Bayer, Johann (1572–1625)
  225. Be Stars
  226. Becklin–Neugebauer Object (BN Object)
  227. Beer, Wilhelm (1797–1850)
  228. Beijing Astronomical Observatory
  229. Bell, Susan Jocelyn [name following her marriage Burnell, or Bell-Burnell] (1943–)
  230. Bennett, Willard Harrison (1903–87)
  231. BeppoSAX (Satellite for X-ray Astronomy)
  232. Bessel, Friedrich Wilhelm (1784–1846)
  233. Beta Pictoris
  234. Beta Regio
  235. Betelgeuse
  236. Bethe, Hans Albrecht (1906–)
  237. Bevis, John (1695–1771)
  238. Biela, Wilhelm von (1782–1856)
  239. Bielids
  240. Biermann, Ludwig Franz Benedikt (1907–86)
  241. Big Bang Theory
  242. Big Bear Solar Observatory
  243. Big Dipper
  244. Binary Stars in Globular Clusters
  245. Binary Stars in Planetary Nebulae
  246. Binary Stars: Detached
  247. Binary Stars: Overview
  248. Binary System
  249. Binocular Astronomy
  250. Biot, Jean-Baptiste (1774–1862)
  251. Birkeland, Kristian (1868–1917)
  252. BiSON Network
  253. BL Lacertae
  254. BL Lacertae Objects
  255. Blaauw, Adriaan (1914)
  256. Black Drop
  257. Black Eye Galaxy
  258. Black Hole
  259. Black-Body Radiation
  260. Black-Hole Candidates in X-ray Binaries
  261. Blazar
  262. Blink Comparator
  263. Blinking Planetary (NGC 6826)
  264. Bliss, Nathaniel (1700–64)
  265. Blue Stars at High Galactic Latitudes
  266. Blue Stragglers
  267. Bode, Johann Elert (1747–1826)
  268. Bode’s Law
  269. Bok, Bart Jan (1906–83)
  270. Bolide
  271. Bolton, John Gatenby (1922–93)
  272. Bond, William Cranch (1789–1859) and Bond, George Phillips (1825–65)
  273. Bondi, Hermann (1919–)
  274. Bonestell, Chesley (1888–1986)
  275. BOOMERANG
  276. Boötes
  277. Borelli, Giovanni Alfonso (1608–79)
  278. Boscovich, Ruggero Giuseppe (1711–87)
  279. Bouguer, Pierre (1698–1758)
  280. Boulliau, Ismael (1605–94)
  281. Bouvard, Alexis (1767–1843)
  282. Bowditch, Nathaniel (1773–1838)
  283. Bowen, Edward George [‘Taffy’] (1911–91)
  284. Bowen, Ira Sprague [‘Ike’] (1898–1973)
  285. Boyle, Willard S (1924–)
  286. Boys, Charles Vernon (1855–1944)
  287. Bradley, James (1693–1762)
  288. Brahmagupta (c 598–c 665)
  289. Brashear, John Alfred (1840–1920)
  290. Brattle, Thomas (1658–1713)
  291. Braun, Wernher von (1912–77)
  292. Breccia
  293. Briggs, Henry (1561–1630)
  294. Bright Quasar 3C 273
  295. Brisbane, Thomas Makdougall (1773–1860)
  296. British Astronomical Association
  297. British Astronomy
  298. Brorsen, Theodore (1819–95)
  299. Brouwer, Dirk (1902–66)
  300. Brown, Ernest William (1866–1938)
  301. Brown, Robert Hanbury (1916–)
  302. Bruno, Giordano (1548–1600)
  303. Bubble Nebula (NGC 7635)
  304. Buffon, Georges Louis Leclerc Comte de (1707–88)
  305. Bulgarian Academy of Sciences, Institute of Astronomy
  306. Burbidge, Eleanor Margaret Peachey (1919−)
  307. Buridan [Buridano], John (bf. fourteenth century)
  308. Burnham, Sherburne Wesley (1838–1921)
  309. Byurakan Astrophysical Observatory
  310. Caelum
  311. Cagliari Astronomical Observatory
  312. Calar Alto Observatory
  313. Calendar
  314. Calendar in the Middle East and Europe
  315. California Nebula (NGC 1499)
  316. Callippus of Cyzicus (c. 370-c. 310 BC)
  317. Callisto
  318. Caloris Basin
  319. Caltech Submillimeter Observatory
  320. Camelopardalis
  321. Cameras
  322. Campanella, Tommaso [Giovan Domenico] (1568–1639)
  323. Campani, Giuseppe (1635–1715)
  324. Campanus of Novara [Campano, Giovanni] (1220–96)
  325. Campbell, William Wallace (1862–1938)
  326. Canada-France-Hawaii Telescope
  327. Canadian Astronomy
  328. Canals (Martian)
  329. Cancer
  330. Candy, Michael Philip (1928–94)
  331. Canes Venatici
  332. Canis Major
  333. Canis Minor
  334. Cannon, Annie Jump (1863–1941)
  335. Canopus
  336. Cape York Meteorite
  337. Capella
  338. Capra, Baldassar [Baldassarre] (1580–1626)
  339. Capricornus
  340. Carbon Stars
  341. Carbonaceous Chondrite
  342. Cardan [Cardano; Cardanus], Jerome [Geronimo; Hieronymus; Girolamo] (1501–76)
  343. Carina
  344. Carlsberg Meridian Telescope
  345. Carnegie Observatories
  346. Carrington, Richard Christopher (1826–75)
  347. Carter National Observatory
  348. Cartwheel Galaxy
  349. Cassegrain Telescope
  350. Cassegrain, Laurent (c. 1629–93)
  351. Cassini Dynasty
  352. Cassini, CĂ©sar-François [Cassini de Thury, known as Cassini III] (1714–84)
  353. Cassini, Gian Domenico [Giovanni Domenico; Jean Dominique; known as Cassini I] (1625–1712)
  354. Cassini, Jacques [known as Cassini II] (1677–1756)
  355. Cassini, Jean-Dominique [known as Cassini IV] (1748–1845)
  356. Cassini/Huygens Mission
  357. Cassiopeia
  358. Cassiopeia A
  359. Castelli, Benedetto (1578–1643)
  360. Castor
  361. Cat’s Eye Nebula (NGC 6543)
  362. Cataclysmic Binaries: Classical and Recurrent Novae
  363. Cataclysmic Variables: the Magnetic Systems
  364. Cavendish, Henry (1731–1810)
  365. CCDs, Filters and CCD Photometry for Amateurs
  366. Celestial Coordinates
  367. Celestial Equator
  368. Celestial Latitude
  369. Celestial Longitude
  370. Celestial Mechanics
  371. Celestial Mechanics in the Eighteenth and Nineteenth Centuries
  372. Celestial Poles
  373. Celestial Sphere
  374. Cellarius, Andreas (fl. seventeenth century)
  375. Celsius, Anders (1701–44)
  376. Centaurs
  377. Centaurus
  378. Center for Astrophysical Research in Antarctica
  379. Center for High Angular Resolution Astronomy
  380. Centre National d’Etudes Spatiales
  381. Cepheid Period–Luminosity Relation
  382. Cepheus
  383. Ceres
  384. CERN
  385. Cerro Tololo Inter-American Observatory (CTIO)
  386. Cetus
  387. CH Cygni
  388. CH Stars and Barium Stars
  389. Challis, James (1803–82)
  390. Chamaeleon
  391. Chamberlin, Thomas Chrowder (1843–1928)
  392. Chandra X-ray Observatory
  393. Chandrasekhar, Subrahmanyan (1910–95)
  394. Charge-coupled Device
  395. Charlier, Carl Vilhelm Ludwig (1862–1934)
  396. Chaucer, Geoffrey (c. 1343–1400)
  397. Chemical Compositions of Stars
  398. Chicxulub Basin
  399. Chinese Astronomical Society
  400. Chinese Astronomy
  401. Chinese Astronomy in History
  402. Chiron
  403. Chladni, Ernst Florens Friedrich (1756–1827)
  404. Chondrites
  405. Christiansen, Wilbur Norman (1913–)
  406. Christie, Sir William Henry Mahoney (1845–1922)
  407. Chromatic Aberration
  408. Chromosphere
  409. Chromosphere: Emerging Flux Regions
  410. Chromosphere: Fibrils
  411. Chromosphere: Heating Mechanisms
  412. Chromosphere: Magnetic Canopy
  413. Chromosphere: Network
  414. Chromosphere: Spicules
  415. Chromosphere: Thermal Bifurcation
  416. Cidenas (fl. fourth century BC)
  417. Circinus
  418. Circumpolar Stars
  419. Clairaut, Alexis Claude (1713–65)
  420. Clark, Alvan (1804–87), Clark, George Bassett (1827–91), and Clark, Alvan Graham (1832–97)
  421. Clarke, Arthur C (1917–)
  422. Classification of Stellar Spectra
  423. Clavius, Christoph (1538–1612)
  424. Clementine
  425. Climate
  426. Close Binary Stars
  427. Close Binary Stars: Formation and Evolution
  428. Clouds in Planetary Atmospheres
  429. Clown Face Nebula (NGC 2392)
  430. Cluster
  431. Cluster Membership
  432. Cluster of Galaxies
  433. Co-orbital Satellites
  434. Coalsack
  435. Collimation
  436. Collisionless Processes in Astrophysical Plasmas
  437. Colombo, Giuseppe (‘Bepi’) (1920–84)
  438. Columba
  439. Coma
  440. Coma Berenices
  441. Coma Cluster
  442. Coma, Cometary
  443. Combustion
  444. Comet Arend–Roland (C/1956 R1)
  445. Comet Bennett (C/1969 Y1)
  446. Comet Biela (3D/Biela)
  447. Comet de Chéseaux (C/1743 X1)
  448. Comet Donati (C/1858 L1)
  449. Comet Encke (2P/Encke)
  450. Comet Family
  451. Comet Giacobini–Zinner (21P/Giacobini–Zinner)
  452. Comet Hale-Bopp (C/1995 O1)
  453. Comet Halley (1P/Halley)
  454. Comet Hyakutake (C/1996 B2)
  455. Comet Ikeya-Seki (C/1965 S1)
  456. Comet IRAS–Araki–Alcock (C/1983 H1)
  457. Comet Kohoutek (C/1973 E1)
  458. Comet LINEAR (C/1999 S4)
  459. Comet Swift–Tuttle (109P/Swift–Tuttle)
  460. Comet Tempel–Tuttle (55P/Tempel–Tuttle)
  461. Comet West (C/1975 V1)
  462. Cometary Atmospheres
  463. Cometary Globule
  464. Cometary Nuclei
  465. Cometary Tails
  466. Comets
  467. Comets: Amateur Observing by Photography
  468. Comets: Kreutz Sungrazing
  469. Comets: Observing with CCDs by Amateurs
  470. Comets: Search and Discovery
  471. Common, Andrew (1841–1903)
  472. Compact Groups of Galaxies
  473. Compton Gamma Ray Observatory (CGRO)
  474. Comrie, Leslie John (1893–1950)
  475. Cone Nebula
  476. Conic Sections
  477. Conjunction
  478. Constellation
  479. Constellation Maps
  480. Constellations, Stars and Deep-Sky Objects: Nomenclature
  481. Continuous Spectrum
  482. Contour (Comet Nucleus Tour)
  483. Cook, James (1728–79)
  484. Cooling Flows
  485. Copenhagen University Astronomical Observatory
  486. Copernican System
  487. Copernicus (Crater)
  488. Copernicus (OAO-3)
  489. Cor Caroli
  490. Core
  491. Corona
  492. Corona Australis
  493. Corona Borealis
  494. Coronagraphs
  495. Coronal Cavities
  496. Coronal Heating Mechanisms
  497. Coronal Holes
  498. Coronal Loops
  499. Coronal Streamers
  500. Coronas
  501. Coronelli, Vincenzo Maria (1650–1718)
  502. Correlation Function and Power Spectra in Cosmology
  503. Correlators
  504. Corvus
  505. COS-B (Celestial Observation Satellite)
  506. Cosimo II de’ Medici (1590–1621)
  507. Cosmic Abundance of Elements
  508. Cosmic Background Explorer: COBE
  509. Cosmic Magnetic Fields: Origin of
  510. Cosmic Microwave Background
  511. Cosmic Rays
  512. Cosmic Rays: Extensive Air Showers
  513. Cosmic Rays: Propagation in the Heliosphere
  514. Cosmological Model
  515. Cosmological Principle
  516. Cosmology
  517. Cosmology: A Brief History
  518. Cosmology Standard Model
  519. Cosmos
  520. Cotes, Roger (1682–1716)
  521. Cowling, Thomas George (1906–90)
  522. Crab Nebula (M1, NGC 1952)
  523. Crab Pulsar
  524. Crabtree, William (1610–44)
  525. CramĂ©r–Rao Limit (or minimum-variance bound)
  526. Crater Constellation
  527. Craters
  528. Crescent
  529. Crimean Astrophysical Observatory
  530. Critical Density
  531. Crust
  532. Crux
  533. Cubewano
  534. Culmination
  535. Culpeper, Nicholas (1616–54)
  536. Cunitz [Cunitia], Maria (1610–64)
  537. Curtis, Heber Doust (1872–1942)
  538. Cusp Cap
  539. Cygnus
  540. Cygnus A
  541. Cygnus Loop
  542. Cygnus X-1
  543. Cysat, Johann Baptist [known as Cysatus] (1586–1657)
  544. d’Alembert, Jean-Baptiste Le Rond (1717–83)
  545. d’Arrest, Heinrich Louis (1822–75)
  546. Danish Space Research Institute
  547. Dante Alighieri (1265–1321)
  548. Dante, Egnatio [Egnazio, Ignazio] (1536–86)
  549. Dark Matter in Galaxies
  550. Dark Matter: Its Nature
  551. Dark Nebula
  552. Darwin, George Howard (1845–1912)
  553. Davenport, William (1782–1823)
  554. David Dunlap Observatory
  555. Dawes, William Rutter (1799–1868)
  556. Dawes’ Limit
  557. Day
  558. DB Pulsating Stars
  559. de ChĂ©seaux, Philippe Loys (1718–51)
  560. de Sitter, Willem (1872–1934)
  561. Deceleration Parameter
  562. Declination
  563. Dee, John (1527–1608)
  564. Deep Impact
  565. Deep Space (Space Technology)
  566. Deep Space 1
  567. Degenerate Matter
  568. Delambre, Jean Baptiste Joseph (1749–1822)
  569. Delaunay, Charles Eugene (1816–72)
  570. Delisle, Joseph-Nicolas (fl. eighteenth century)
  571. Delphinus
  572. Delta Aquarids
  573. Delta Cephei
  574. Democritus of Abdera (c. 470–c. 380 BC)
  575. Deneb
  576. Denning, William Frederick (1848–1931)
  577. Density
  578. Descartes, RenĂ© (1596–1650)
  579. Deslandres, Henri Alexandre (1853–1948)
  580. Detection of Faint Objects
  581. Detectors: Photography
  582. Detectors: Superconducting Tunnel Junction Devices
  583. Diamond Ring
  584. Dichotomy
  585. Dicke, Robert Henry (1916–)
  586. Differential Rotation
  587. Differentiation
  588. Diffraction
  589. Diffraction Grating
  590. Diffuse Interstellar Bands
  591. Digges, Leonard (c 1520–c 1559) and Digges, Thomas (1545/6-95)
  592. Dione
  593. Direct Motion
  594. Disconnection Event
  595. Disk Galaxies
  596. Dispersion
  597. Distances (from Antiquity to 1900)
  598. Distribution of Galaxies, Clusters, and Superclusters
  599. Diurnal Motion
  600. Divided Instruments
  601. Divini, Eustachio (1610–85)
  602. Dixon, Jeremiah (1733–79)
  603. Dobson Unit
  604. Dobsonian Telescope
  605. Dollond, John (1706–61)
  606. Dome
  607. Dominion Astrophysical Observatory
  608. Dominion Radio Astrophysical Observatory
  609. Donati, Giambattista [Giovanni Battista] (1826–73)
  610. Doppelmayr, Johann Gabriel (1671–1750)
  611. Doppler Effect
  612. Doppler, Johann Christian Andreas (1803–53)
  613. Dorado
  614. Double Star
  615. Double Stars: Visual and Imaging Observations by Amateurs
  616. Douglass, Andrew Ellicott (1867–1962)
  617. DQ Herculis
  618. Draco
  619. Drake, Frank Donald (1930–)
  620. Draper, Henry (1837–82)
  621. Dreyer, John Louis Emil (1852–1926)
  622. Dubhe
  623. Dudley Observatory
  624. Dumbbell Nebula (M27, NGC 6853)
  625. Duner, Nils Christoffel (1839–1914)
  626. Dunlop, James (1793–1848)
  627. Dunsink Observatory
  628. Dust Tail, Cometary
  629. Dusty Circumstellar Disks
  630. Dutch Astronomy
  631. Dwarf Elliptical Galaxies
  632. Dwarf Galaxy
  633. Dwarf Irregular Galaxies
  634. Dwarf Spheroidal Galaxies
  635. Dwingeloo Observatory
  636. Dyer Observatory
  637. Dynamical Reference Frame
  638. Dynamics
  639. Dynamics Explorer (Explorer 62 and 63)
  640. Dynamo Theory
  641. Dynamos: Solar and Stellar
  642. Dyson, Sir Frank Watson (1868–1939)
  643. Eagle Nebula (IC 4703)
  644. Earth: Space-based Observations
  645. Earth’s Atmosphere
  646. Earth’s Interior
  647. Earth’s Rotation
  648. Earth’s Rotation: Theory
  649. Earthshine
  650. Eckert, Wallace John (1902–71)
  651. Eclipse
  652. Eclipsing Binary Stars
  653. Ecliptic
  654. Ecosphere
  655. Eddington, Sir Arthur Stanley (1882–1944)
  656. Edgeworth, Kenneth Essex (1880–1972)
  657. Education
  658. Effective Temperature Scale and Bolometric Corrections
  659. Effelsberg Radio Telescope
  660. Egg Nebula (CRL 2688)
  661. Einstein Observatory (HEAO-2)
  662. Einstein, Albert (1879–1955)
  663. EISCAT
  664. Ejecta
  665. Electromagnetic Radiation
  666. Electromagnetic Spectrum
  667. Electron
  668. Electronvolt
  669. Electroweak Force
  670. Element, Chemical
  671. Elementary Particles
  672. Ellipse
  673. Elliptical Galaxies
  674. Elongation
  675. Elsasser, Walter M (1904–91)
  676. Emission Spectrum
  677. Empedocles of Akragas (c. 492–c. 432 BC)
  678. Enceladus
  679. Encke, Johann Franz (1791–1865)
  680. Energy
  681. Environmental Threat to Astronomy
  682. Eötvös, Baron LĂłrĂĄnd [Roland] von (1848–1919)
  683. Ephemerides
  684. Epicurus of Samos (341–270 BC)
  685. Epoch
  686. Epsilon Aurigae
  687. Epsilon Lyrae
  688. Equation of Time
  689. Equator-S
  690. Equatorial Mounting
  691. Equinox
  692. Equuleus
  693. Eratosthenes of Cyrene (c. 276–c. 196 BC
  694. Erfle, Heinrich Valentin (1884–1923)
  695. Eridanus
  696. Eros
  697. Escape Velocity
  698. Eta Aquarids
  699. Eta Carinae
  700. Eta Carinae Nebula
  701. Ether (or Aether)
  702. Eudoxus of Cnidus (c. 400–c. 347 BC)
  703. Euler, Leonhard (1707–83)
  704. Euro-Asian Astronomical Society
  705. Europa
  706. Europa Orbiter
  707. European Astronomical Society
  708. European Southern Observatory (ESO)
  709. European Space Agency (ESA)
  710. Evening Star
  711. Evershed, John (1864–1956)
  712. Excitation and Ionization
  713. Exit Pupil
  714. Exobiology
  715. Exoplanets: Observing by Amateurs
  716. Exosat (European X-ray Observatory Satellite)
  717. Expanding Universe
  718. Explorer
  719. Extended Atmospheres
  720. Extragalactic Astronomy c. 1900-1950
  721. Extragalactic Background Light
  722. Extragalactic Reference Frames
  723. Extrasolar Planetary Companions and Brown Dwarfs
  724. Extrasolar Planets
  725. Extreme Ultraviolet Explorer (EUVE)
  726. Eye Relief
  727. Eyepiece
  728. Faber-Jackson Relationship
  729. Fabri [Fabry], Honoré (1607-88)
  730. Fabricius, David (1564–1617) and Fabricius, Johannes (1587–1616)
  731. Fabry, Marie Paul Auguste Charles (1867-1945)
  732. Faculae
  733. Fallows, Fearon (1789–1831)
  734. False Cross
  735. Far-Infrared and Submillimetre Telescope (FIRST)
  736. Far-Ultraviolet Spectroscopic Explorer (FUSE)
  737. FAST (Fast Auroral Snapshot Explorer/Explorer 70)
  738. Fermi, Enrico (1901–54)
  739. FG Sagittae (FG Sge)
  740. Field of View
  741. Filament
  742. Filar Micrometer
  743. Filterbanks
  744. Filters
  745. Finder
  746. Finding and Collecting Meteorites
  747. FinĂ©, Oronce (1494–1555)
  748. Fireball
  749. First Point of Aries
  750. First Point of Libra
  751. Fisher, Sir Ronald Aylmer (1890–1962)
  752. Fission
  753. Fitzgerald [FitzGerald], George Francis (1851–1901)
  754. Five College Radio Astronomy Observatory
  755. Fizeau, Armand (1819–96)
  756. Flagstaff Field Center
  757. Flame Nebula (NGC 2024)
  758. Flammarion, Nicolas Camille (1842–1925)
  759. Flamsteed, John (1646–1719)
  760. Flare
  761. Flash Spectrum
  762. Fleming, Williamina Paton Stevens (1857–1911)
  763. Fluid Dynamics
  764. Flux Density
  765. Focal Length
  766. Focal Ratio
  767. Focus
  768. Fomalhaut
  769. Fontenelle, Bernard le Bouyer de [Bernhard le Bovier de] (1657–1757)
  770. Force-Free Magnetic Fields
  771. Fornax
  772. Foucault, Jean Bernard LĂ©on (1819–68)
  773. Foucault’s Pendulum
  774. Fowler, Alfred (1868–1940)
  775. Fowler, William Alfred [‘Willy’] (1911–95)
  776. Franklin-Adams, John (1843–1912)
  777. Fraunhofer Lines
  778. Fraunhofer, Joseph von (1787–1826)
  779. Freja
  780. Frequency
  781. Freundlich, Erwin Finlay (1885–1964)
  782. Friedman, Herbert (1916–)
  783. Friedmann [Fridman], Aleksandr [Alexander] Aleksandrovich (1888–1925)
  784. Frost, Robert (1874–1963)
  785. Fuertes Observatory
  786. Fundamental Catalogs
  787. Fundamental Forces
  788. Fundamental Particles
  789. Fundamental Stars
  790. Fusion
  791. Gagarin, Yuri Alekseyevich (1934–1968)
  792. Galactic Astronomy c. 1900–c. 1950
  793. Galactic Bulge
  794. Galactic Latitude
  795. Galactic Longitude
  796. Galactic Metal-Poor Halo
  797. Galactic Nucleus
  798. Galactic Open Clusters
  799. Galactic Plane
  800. Galactic Star Clusters: Observing by Amateurs
  801. Galactic Thick Disk
  802. Galactic Thin Disk
  803. Galactic Year
  804. Galaxies at High Redshift
  805. Galaxies: Classification
  806. Galaxies: Interactions and Mergers
  807. Galaxy
  808. Galaxy Clusters
  809. Galaxy Evolution
  810. Galaxy Formation
  811. Galaxy Morphology-Density Relation
  812. Galaxy Redshift Surveys
  813. Galaxy Structure
  814. Gale, Walter Frederick (1865–1945)
  815. Galilean Telescope
  816. Galileo Galilei
  817. Galileo Mission to Jupiter
  818. Galle, Johann Gottfried (1812–1910)
  819. Gamma Draconis
  820. Gamma Rays
  821. Gamma-Ray Astronomy
  822. Gamma-Ray Bursts
  823. Gamma-Ray Telescopes
  824. Gamow, George (1904–68)
  825. Ganymede
  826. Gas Detectors
  827. Gas Giants
  828. Gas in Galaxies
  829. Gas Tail, Cometary
  830. Gascoigne, Sidney Charles Bartholemew (‘Ben’) (1915–)
  831. Gascoigne, William (1621–44)
  832. Gaseous Nebulae
  833. Gaspra
  834. Gassendi [Gassend], Pierre (1592–1655)
  835. Gauge Bosons
  836. Gauss, Carl Friedrich (1777–1855)
  837. Gellibrand, Henry (1597–1636)
  838. Geminga
  839. Gemini
  840. Gemini Observatory
  841. Geminids
  842. Geminus (c. 130–c. 70 BC)
  843. Gemma Frisius, Reiner [Regner, Regnier] (1508–55)
  844. General Relativity and Gravitation
  845. General Relativity Tests: Binary Pulsars
  846. General Relativity: Solar System Experiments
  847. General Theory of Relativity
  848. Genesis
  849. Geocentric Coordinate System
  850. Geodynamo
  851. Geomagnetic Storm
  852. Geotail
  853. Gerard of Cremona (c. 1114-87)
  854. German Astronomy
  855. Ghost of Jupiter (NGC 3242)
  856. Giacconi, Riccardo (1931−)
  857. Giacobinids
  858. Giant Impactor Theory
  859. Giant Planets
  860. Gibbous
  861. Gilbert [Gilberd], William (1544–1603)
  862. Gill, Sir David (1843–1914)
  863. Ginga (Astro-C)
  864. Giotto
  865. Giovanelli, Ronald Gordon (1915–84)
  866. Glazenap [Glasenapp], Sergej Pavlovich [von] (1848–1937)
  867. Global Oscillation Network Group
  868. Globular Cluster Systems in Interacting Galaxies
  869. Globular Cluster Systems in Normal Galaxies
  870. Globular Cluster X-ray Sources
  871. Globular Clusters
  872. Globule
  873. Goddard Space Flight Center
  874. Goddard, Robert Hutchings (1882–1945)
  875. Gold, Thomas (1920–)
  876. Goldberg, Leo (1918–87)
  877. Goodricke, John (1764–86)
  878. Gould Belt
  879. Gould, Benjamin Apthorp (1824–96)
  880. Graham, George (c. 1674–1751)
  881. Granat
  882. Grand Unified Theory
  883. Granulation
  884. Gravitation
  885. Gravitational Lensing
  886. Gravitational Lensing by Clusters of Galaxies
  887. Gravitational Radiation
  888. Gravitational Radiation Detectors on Earth and in Space
  889. Gravitational Waves
  890. Graviton
  891. Gravity Probe B
  892. Gray, Stephen (1666–1736)
  893. Grazing Incidence Optics
  894. Great Circle
  895. Great Red Spot (GRS)
  896. Great Rift
  897. Great Wall
  898. Green Bank (National Radio Astronomical Observatory)
  899. Greenhouse Effect
  900. Greenstein, Jesse Leonard (1909–)
  901. Gregorian Telescope
  902. Gregory [Gregorie], James (1638–75)
  903. Grimaldi, Francesco Maria (1618–63)
  904. Groombridge 1830
  905. Groups of Galaxies
  906. Grubb, Thomas (1800–78) and Grubb, Howard (1844–1931)
  907. Gruithuisen, Franz von Paula (1744–1852)
  908. Grus
  909. Guide Telescope
  910. Gum Nebula
  911. Gum, Colin (1924–60)
  912. H I Region
  913. H II Regions
  914. Hadley, John (1682–1744)
  915. Hadrons
  916. Hagen, Johann Georg (1847–1930)
  917. HALCA (Highly Advanced Laboratory for Communications and Astronomy/Muses-B)
  918. Hale, George Ellery (1868–1938)
  919. Hall, Asaph (1829–1907)
  920. Halley, Edmond (1656–1742)
  921. Halo, Galactic
  922. Hamilton, James Archibald (1748–1815)
  923. Harding, Karl Ludwig (1765–1834)
  924. Haro, Guillermo (1913–88)
  925. Harriot, Thomas (c. 1560–1621)
  926. Harrison, John (1693–1776)
  927. Hartebeesthoek Radio Astronomy Observatory
  928. Hartmann, Johannes Franz (1865–1936)
  929. Harvard–Smithsonian Center for Astrophysics
  930. Hat Creek Radio Observatory
  931. Hawking, Stephen W (1942–)
  932. Hawkins, Gerald
  933. Hay, William Thompson [Will Hay] (1888–1949)
  934. Haystack Observatory
  935. Heavy Elements
  936. Heckmann, Otto Hermann Leopold (1901–83)
  937. HEGRA Experiment
  938. Hektor
  939. Heliocentric Coordinate System
  940. Helios
  941. Helioseismic Observations
  942. Helioseismology
  943. Helioseismology: Theory
  944. Helium (He)
  945. Helix Nebula (NGC 7293)
  946. Hell [Höll], Maximilian [Miksa] (1720–92)
  947. Hellas Planitia
  948. Helmholtz, Hermann Ludwig Ferdinand von (1821–94)
  949. Henderson, Thomas (1798–1844)
  950. Henry, Paul (1848–1905) and Henry, Prosper (1849–1903) [known as Frùres Henry]
  951. Heracleitus of Ephesus (c. 540–c. 475 BC
  952. Heraclides of Pontus (c. 388–315 BC)
  953. Herbig–Haro Objects and Exciting Stars
  954. Herbig, George Howard (1920–)
  955. Hercules
  956. Hercules X-1
  957. Hermes
  958. Herrick, Edward Claudius (1811–62)
  959. Herrick, Samuel (1911–74)
  960. Herschel Family
  961. Hertzsprung–Russell Diagram
  962. Hertzsprung, Ejnar (1873−1967)
  963. Herzberg Institute of Astrophysics
  964. Herzberg, Gerhard (1904-)
  965. Hesiod (eighth century BC)
  966. Hess, Harry Hammond (1906–69)
  967. Hess, Victor Franz (1883−1964)
  968. Hevelius, Johannes [Jan Hewelcke] (1611–87)
  969. Hewish, Antony (1924– )
  970. Hey, James Stanley (1909–90)
  971. Hidalgo
  972. High Altitude Observatory
  973. High Energy Astrophysical Observatory (HEAO)
  974. High Energy Transient Experiment (HETE) 2
  975. High-density Equation of State of Neutron tars
  976. High-luminosity Stars
  977. High-redshift Quasars
  978. High-velocity Cloud (HVC)
  979. High-velocity Star
  980. High-z Clusters
  981. Hill, George William (1838−1914)
  982. Hind, John R (1823−1895)
  983. Hinotori (Astro-A)
  984. Hipparchus
  985. Hipparcos
  986. Hipparcos and Tycho Catalogues
  987. Hirayama Family
  988. Hiten (Muses-A)
  989. Hoba Meteorite
  990. Hobby-Eberly Telescope
  991. Hoffman, Jeffrey A (1944–)
  992. Hoffmeister, Cuno (1892−1968)
  993. Högbom, Jan (twentieth century)
  994. Hogg [Sawyer Hogg, Hogg-Priestley, Sawyer-Hogg-Priestley], Helen, nee Battles (1905-93)
  995. Hogg, Arthur Robert (1903–66)
  996. Holden, Edward Singleton (1846−1914)
  997. Holmberg, Erik [Eric] Bertil (1908–)
  998. Home Observatories
  999. Homunculus Nebula
  1000. Hooke, Robert (1635−1703)
  1001. Horizon
  1002. Horizontal-branch Stars
  1003. Horologium
  1004. Horrocks, Jeremiah (1619–41)
  1005. Horsehead Nebula (B33)
  1006. Hot Dark Matter
  1007. Hot Stellar Populations in Elliptical Galaxies
  1008. Hour Angle
  1009. Hourglass Nebula (MyCn 18)
  1010. Houzeau de Lehaie, Jean-Charles-Hippolyte-Joseph (1820–88)
  1011. Hoyle, Sir Fred (1915–)
  1012. Hubble Classification
  1013. Hubble constant
  1014. Hubble Deep Fields
  1015. Hubble Diagram
  1016. Hubble Law
  1017. Hubble Space Telescope
  1018. Hubble, Edwin Powell (1889–1953)
  1019. Hubble’s Variable Nebula (NGC 2261)
  1020. Huggins, Margaret Lindsay Murray (1848–1915)
  1021. Huggins, Sir William (1824–1910)
  1022. Hulse, Russell A (1950–)
  1023. Hulst, Hendrik van de (1918–)
  1024. Humason, Milton La Salle (1891–1972)
  1025. Humboldt, Alexander von (1769–1859)
  1026. Huygens, Christiaan (1629–95)
  1027. Hydra
  1028. Hydrodynamic Instabilities
  1029. Hydrogen (H)
  1030. Hydrogen Spectrum
  1031. Hydrus
  1032. Hygiea
  1033. Hypatia of Alexandria (370–415)
  1034. Hyperbola
  1035. Hyperion
  1036. Iapetus
  1037. Ibn Rushd, Abu’l Waleed Muhammad Ibn Ahmad Ibn Muhammad [known as Averroes] (1128–98)
  1038. Ibn Sina, Abu Ali [known as Avicenna] (980–1037)
  1039. Ibrahim, ibn Sinan ibn Thabit ibn Qurra (908–46)
  1040. Icarus
  1041. Ida
  1042. Imaging Near-Earth Space
  1043. Imbrium Basin
  1044. Inclination
  1045. Index Catalog (IC)
  1046. Indian Astronomy: History of
  1047. Indus
  1048. Inertia
  1049. Inferior Planets
  1050. Inflation
  1051. Inflationary Universe
  1052. Information Handling in Astronomy
  1053. Infrared Arrays
  1054. Infrared Astronomy
  1055. Infrared Astronomy Satellite
  1056. Infrared Imagers
  1057. Infrared Space Missions
  1058. Infrared Telescopes
  1059. Ingalls, Albert (1888–1958)
  1060. Inner Planets
  1061. Institut de Radio Astronomie Millimétrique
  1062. Institut National des Sciences de l’Univers
  1063. Institute of Space and Astronautical Science
  1064. Instituto Argentino de RadioastronomĂ­a
  1065. Instituto de Astrofisica de Canarias
  1066. Instrumentation: Adaptive Optics
  1067. Integral (International Gamma Ray Astrophysics Laboratory)
  1068. Interacting Galaxies
  1069. Interball
  1070. Interference
  1071. Interferometer
  1072. Interferometry: Ground
  1073. Intergalactic Medium
  1074. International Astronomical Union
  1075. International Atomic Time
  1076. International Cometary Explorer (ICE)
  1077. International Dark-Sky Association
  1078. International Space Science Institute
  1079. International Sun-Earth Explorer (ISEE)
  1080. International Ultraviolet Explorer (lUE)
  1081. Interplanetary Dust
  1082. Interplanetary Network
  1083. Interstellar Absorption Lines
  1084. Interstellar Chemistry
  1085. Interstellar Grains
  1086. Interstellar Magnetic Fields
  1087. Interstellar Matter
  1088. Interstellar Molecular Clouds
  1089. Intracluster Medium
  1090. Io: Plasma Torus
  1091. Io: Volcanism and Geophysics
  1092. Ion
  1093. Ionization
  1094. IRIS (ESRO-2B)
  1095. Iris (Infrared Imaging Surveyor/Astro-F)
  1096. Irish Astronomy
  1097. Iron Meteorite
  1098. Irregular Galaxy
  1099. Isaac Newton Group of Telescopes
  1100. Ishtar Terra
  1101. Islamic Astronomy
  1102. Isotope
  1103. Isotopes in the Interstellar Medium
  1104. Isotopic Anomalies
  1105. Istituto di Radioastronomia, Bologna
  1106. Italian Space Agency (ASI)
  1107. Ivory, Sir James (1765–1842)
  1108. James Clerk Maxwell Telescope
  1109. Jansky, Karl Guthe (1905–50)
  1110. Janssen, Pierre Jules Cesar (1824–1907)
  1111. Japanese Astronomy
  1112. Jeans, Sir James Hopwood (1877–1946)
  1113. Jeffreys, Sir Harold (1891–1989)
  1114. Jet Propulsion Laboratory (JPL)
  1115. Jodrell Bank Observatory
  1116. John of Holywood [known as Sacrobosco] (c. 1200)
  1117. Johnson Space Center
  1118. Johnson, Harold Lester (1921–80)
  1119. Joint Institute for Laboratory Astrophysics (JILA)
  1120. Joint Institute for VLBI in Europe
  1121. Joy, Alfred Harrison (1882–1973)
  1122. Julian Date (J.D.)
  1123. Juno
  1124. Jupiter
  1125. Jupiter Atmosphere
  1126. Jupiter: Magnetosphere
  1127. Jupiter: Rings
  1128. Jupiter: Satellites
  1129. Kaiser, Frederik [Frederick] (1808–72)
  1130. Kant, Immanuel (1724–1804)
  1131. Kanzelhöhe Solar Observatory
  1132. Kapteyn Astronomical Institute
  1133. Kapteyn, Jacobus Cornelius (1851–1922)
  1134. Kapteyn’s Star
  1135. Karin Cluster
  1136. Keeler, James Edward (1857–1900)
  1137. Kepler
  1138. Kepler’s Laws
  1139. Kepler’s Star
  1140. Keyhole Nebula (NGC 3324)
  1141. Khayyam [al-Khayyam], Omar [Abu ol-Fath ebn-Ebrahim ‘Omar ol-Khayyami of Nishapur] (c. 1044–c. 1123)
  1142. Kiddinu (340 BC–?)
  1143. Kiepenheuer-Institut fĂŒr Sonnenphysik
  1144. Kinetic Theory of Gases
  1145. Kirch family
  1146. Kircher, Athanasius (1602–80)
  1147. Kirchhoff, Gustav Robert (1824–87)
  1148. Kirkwood Gaps
  1149. Kirkwood, Daniel (1814–95)
  1150. Kitt Peak National Observatory
  1151. Kleinmann–Low Nebula (KL Nebula)
  1152. Kolmogorov, Andrey Nikolayevich (1903–87)
  1153. Konkoly Observatory
  1154. Korff, Serge Alexander (1906–89)
  1155. Korolyov [Koroljow], Sergej [Sergey, Sergei] Pavlovich [Pawlowitsch] (1907–66)
  1156. Kraus, John (1910–)
  1157. Kroto, Sir Harold (1939–)
  1158. Kuhn, Thomas S (1922–96)
  1159. Kuiper Belt
  1160. Kuiper, Gerard Peter (1905–73)
  1161. Kulik, Leonid (1883–1942)
  1162. Kuo Shou-Ching (1231–1316)
  1163. La Condamine, Charles Marie de (1701–74)
  1164. La Hire, Philippe de [Philippe I] (1640–1718) and La Hire, Gabriel-Philippe de [Philippe II] (1677–19)
  1165. La Plata Observatory
  1166. Laboratory and Space Measurements of the Effects of Gravity
  1167. Lacaille 9352
  1168. Lacaille, AbbĂ© Nicholas [Nicolas] Louis de (1713–62)
  1169. Lacerta
  1170. Lada Terra
  1171. Lagoon Nebula (M8, NGC 6523)
  1172. Lagrange, Joseph-Louis (1736–13)
  1173. Lagrangian Points
  1174. Lalande, Joseph-JĂ©rĂŽme Lefrançais de (1732–1807)
  1175. Lambert, Johann Heinrich (1728–77)
  1176. Lamont, Johann von (1805–79)
  1177. Langren [Langrenus], Michael Florent van [Michael Florentius] (c. 1600–75)
  1178. Lansberge, Philip van [Lansbergen, Philips] (1561–1632)
  1179. Laplace, Pierre-Simon (1749–1827)
  1180. Large Binocular Telescope
  1181. Large Hot Subdwarfs and Extreme Horizontal Branch Stars
  1182. Large Magellanic Cloud
  1183. Large-Scale Plasma Dynamics
  1184. Larmor, Joseph (1857–1942)
  1185. Las Campanas Observatory
  1186. Lassell, William (1799–1880)
  1187. Lasser, David (1902–)
  1188. Lavanha, Joao Baptista (1550–1624)
  1189. LDEF (Long Duration Exposure Facility)
  1190. Le Fevre [Le Fùvre; LeFebvre], Jean (1652–1706)
  1191. Le Gentil de la Galaziere, Guillaume-Joseph-Hyacinthe-Jean-Baptiste (1725–92)
  1192. Leavitt, Henrietta Swan (1868–1921)
  1193. Legendre, Adrien-Marie (1752–1833)
  1194. Leiden Observatory
  1195. LemaĂźtre, AbbĂ© Georges Edouard (1894–1966)
  1196. Lemonnier, Pierre Charles (1715–99)
  1197. Lenticular Galaxy
  1198. Leo
  1199. Leo Group
  1200. Leo Minor
  1201. Leonardo da Vinci (1452–1519)
  1202. Leonids
  1203. LĂ©paute, Nicole-Reine Etable, nĂ©e de la BriĂ©re (1723–88)
  1204. Leptons
  1205. Lepus
  1206. Lescarbault, Edmond
  1207. Leucippus (ƒl. fifth century BC)
  1208. Leuschner, Armin Otto (1868–1953)
  1209. Leverrier [Le Verrier], Urbain Jean Joseph (1811–77)
  1210. Levi ben Gerson (1288–1344)
  1211. Lexell, Anders John (1740–84)
  1212. Ley, Willy (1906–69)
  1213. Libra
  1214. Libration
  1215. Lick Observatory
  1216. Life on Other Worlds
  1217. Life: Origins and Possible Distribution in the Universe
  1218. Light
  1219. Light Element Nucleosynthesis
  1220. Light Year (l.y.)
  1221. Light-Gathering Power (Light Grasp)
  1222. Light Pollution
  1223. Limb
  1224. Lindblad, Bertil (1895–1965)
  1225. Lipperhey [Lippershey], Hans [Jan] (1570?–1619)
  1226. Lithuanian Astronomy
  1227. Little Dumbbell Nebula (M76, NGC 650–51)
  1228. Liu Xin (first century BC–first century AD)
  1229. Liverpool John Moores University Astrophysics Research Institute
  1230. Lobate Scarp
  1231. Local Group
  1232. Lockyer, Joseph Norman (1836–1920)
  1233. Logan, James (1674–1751)
  1234. Lohrmann, Wilhelm Gotthelf (1796–1840)
  1235. Lomonosov, Mikhail V (1711–65)
  1236. Long-period Comet
  1237. Lorentz, Hendrik Antoon (1853–1928)
  1238. Lovell, Alfred Charles Bernard [Sir Bernard] (1913–)
  1239. Low Surface Brightness Galaxies
  1240. Lowell Observatory
  1241. Lowell, Percival (1855–1916)
  1242. Lucretius (95–55 BC)
  1243. Luminosity Function of Galaxies
  1244. Luminous Blue Variables
  1245. Luna
  1246. Lunar Orbiter
  1247. Lunar Prospector
  1248. Lunar Transient Phenomenon (LTP)
  1249. Lunar-A
  1250. Lund Observatory
  1251. Lunokhod
  1252. Lupus
  1253. Luyten, Willem Jacob (1899–1994)
  1254. Lyman Alpha Absorption: The Damped Systems
  1255. Lyman Alpha Forest
  1256. Lynx
  1257. Lyot, Bernard Ferdinand (1897–1952)
  1258. Lyra
  1259. Lyrids
  1260. M1
  1261. M2
  1262. M3
  1263. M4
  1264. M5
  1265. M6
  1266. M7
  1267. M8
  1268. M9
  1269. M10
  1270. M11
  1271. M12
  1272. M13
  1273. M14
  1274. M15
  1275. M16
  1276. M17
  1277. M18
  1278. M19
  1279. M20
  1280. M21
  1281. M22
  1282. M23
  1283. M24
  1284. M25
  1285. M26
  1286. M27
  1287. M28
  1288. M29
  1289. M30
  1290. M31: The Old Stellar Populations
  1291. M32
  1292. M33
  1293. M34
  1294. M35
  1295. M36
  1296. M37
  1297. M38
  1298. M39
  1299. M40
  1300. M41
  1301. M42
  1302. M43
  1303. M44
  1304. M45
  1305. M46
  1306. M47
  1307. M48
  1308. M49
  1309. M50
  1310. M51
  1311. M52
  1312. M53
  1313. M54
  1314. M55
  1315. M56
  1316. M57
  1317. M58
  1318. M59
  1319. M60
  1320. M61
  1321. M62
  1322. M63
  1323. M64
  1324. M65
  1325. M66
  1326. M67
  1327. M68
  1328. M69
  1329. M70
  1330. M71
  1331. M72
  1332. M73
  1333. M74
  1334. M75
  1335. M76
  1336. M77
  1337. M78
  1338. M79
  1339. M80
  1340. M81
  1341. M82: The Starburst Galaxy
  1342. M83
  1343. M84
  1344. M85
  1345. M86
  1346. M87: The Massive Galaxy
  1347. M87: The Nucleus and Jet
  1348. M88
  1349. M89
  1350. M90
  1351. M91
  1352. M92
  1353. M93
  1354. M94
  1355. M95
  1356. M96
  1357. M97
  1358. M98
  1359. M99
  1360. M100
  1361. M101
  1362. M102
  1363. M103
  1364. M104
  1365. M105
  1366. M106
  1367. M107
  1368. M108
  1369. M109
  1370. M110
  1371. Mach, Ernst (1838–1916)
  1372. Maclaurin, Colin (1698–1746)
  1373. Maclear, Thomas (1794–1879)
  1374. Madler, Johann Heinrich von (1794–1874)
  1375. Maffei 1 and 2
  1376. Magellan
  1377. Magellan, Ferdinand (1480?–1521)
  1378. Magellanic Clouds: Interstellar Phenomena
  1379. Magellanic Clouds: Stellar Populations
  1380. Magellanic Stream
  1381. Magnenus [Magnen, Magnien], Johann Chrysostom (c. 1590–c. 1679)
  1382. Magnetars
  1383. Magnetic Buoyancy
  1384. Magnetic Fields in Stars
  1385. Magnetic Helicity
  1386. Magnetic Reconnection
  1387. Magnetohydrodynamic Instabilities
  1388. Magnetohydrodynamic Waves
  1389. Magnetohydrodynamics
  1390. Magnetohydrodynamics of Accretion Disks
  1391. Magnetohydrodynamics of Astrophysical Winds
  1392. Magnetohydrodynamics: Magnetic Reconnection and Turbulence
  1393. Magnetohydrodynamics: Magnetoconvection
  1394. Magnetosphere of Earth
  1395. Magnetosphere of Earth: Bow Shock
  1396. Magnetosphere of Earth: Convection
  1397. Magnetosphere of Earth: Dayside Cusp
  1398. Magnetosphere of Earth: Geomagnetic Storms and Solar Wind Origins
  1399. Magnetosphere of Earth: Geomagnetic Tail
  1400. Magnetosphere of Earth: Magnetopause
  1401. Magnetosphere of Earth: Plasma Sheet
  1402. Magnetosphere of Earth: Plasmasphere
  1403. Magnetosphere of Earth: Radiation Belts
  1404. Magnetosphere of Earth: Ring Current
  1405. Magnetosphere of Earth: Substorms
  1406. Magnetosphere of Earth: Waves
  1407. Magnetospheres: Jupiter, Radio Emissions
  1408. Magnetospheres: Jupiter, Satellite Interactions
  1409. Magnetospheres: Plasma-Ring/Dust Interactions
  1410. Magnification
  1411. Magnitude Scales and Photometric Systems
  1412. Maidanak Observatory
  1413. Major Planets
  1414. Maksutov Telescope
  1415. Maksutov, Dmitri Dmitievich (1896–1964)
  1416. Malin, David (20th century)
  1417. Malmquist Bias and Completeness Limits
  1418. Malmquist, Gunnar (1893–1982)
  1419. Mantle
  1420. Maraldi, Jean-Dominique [Giovanni, Maraldi II] (1709–88)
  1421. Mare (pl: maria)
  1422. Mariner Missions
  1423. Marius [Mayr], Simon (1573–1624)
  1424. Mars
  1425. Mars
  1426. Mars Express
  1427. Mars Global Surveyor
  1428. Mars Odyssey
  1429. Mars Pathfinder
  1430. Mars Surveyor 2001
  1431. Mars: Atmosphere
  1432. Mars: Climate History
  1433. Mars: Core and Magnetism
  1434. Mars: Observing by Amateurs
  1435. Mars: Surface
  1436. Mars: Water and the Martian Landscape
  1437. Marshall Space Flight Center
  1438. Maskelyne, Nevil (1732–1811)
  1439. Mason, Charles (1730–87)
  1440. Mass
  1441. Massey, Harrie Stewart Wilson (1908–83)
  1442. MĂ€stlin, Michael (1550–1631)
  1443. Matter
  1444. Maunder, E W (1851–1928) and Maunder, Mrs A S D
  1445. Maupertuis, Pierre Louis Moreau de (1698–1759)
  1446. Maurolico [Marul, Marol], Francesco (1494–1575)
  1447. Max-Planck-Institut fĂŒr Astronomie
  1448. Max-Planck-Institut fĂŒr Astrophysik
  1449. Max-Planck-Institut fĂŒr Extraterrestrische Physik
  1450. Max-Planck-Institut fĂŒr Radioastronomie
  1451. Maxwell Montes
  1452. Maxwell, James Clerk (1831–79)
  1453. Mayan Astronomy
  1454. Mayer, Tobias (1723–62)
  1455. McCrea, William Hunter (1904–98)
  1456. McDonald Observatory
  1457. MDM Observatory
  1458. Mean Solar Time
  1459. Measuring Machines
  1460. Media
  1461. Medieval Cosmology
  1462. Mégantic Astronomical Observatory
  1463. Menelaus of Alexandria (c. 70–c. 130)
  1464. Mensa
  1465. Menzel, Donald (1901–76)
  1466. Merak
  1467. Mercator, Gerardus [Gerhard Kremer] (1512–94)
  1468. Mercury
  1469. Mercury and Venus: Observing by Amateurs
  1470. Mercury: Magnetosphere
  1471. Meridian
  1472. MERLIN/VLBI National Facility
  1473. Merrill, Paul Willard (1887–1961)
  1474. Mersenne, Marin (1588–1648)
  1475. Meshchersky, Ivan Vsevolodovich (1859–1935)
  1476. Mesons
  1477. MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging Mission)
  1478. Messier Catalog
  1479. Messier, Charles (1730–1817)
  1480. Meteor Crater
  1481. Meteor Shower
  1482. Meteor Storm
  1483. Meteor Stream
  1484. Meteorites
  1485. Meteorites from Mars
  1486. Meteoroid
  1487. Meteors
  1488. Meteors: Amateur Observing by Photography
  1489. Metonic Cycle
  1490. Metos of Athens (c. 440 BC–?)
  1491. Michell, John (1724–93)
  1492. Michelson–Morley Experiment
  1493. Michelson, Albert (1852–1931)
  1494. Michigan Radio Astronomy Observatory
  1495. MicroChannel Plate Detectors
  1496. Microlensing
  1497. Micrometeorite
  1498. Microscopium
  1499. Mid-Infrared Instrumentation
  1500. Milankovitch, [Milankovič] Milutin (1879–1958)
  1501. Milky Way Galaxy
  1502. Millikan, Robert Andrews (1868–1953)
  1503. Millimeter and Submillimeter Astronomy
  1504. Mills, Bernard Yarnton (1920–)
  1505. Milne, Edward Arthur (1896–1950)
  1506. Mimas
  1507. Mineur, Henri (1899–1954)
  1508. Minkowski, Hermann (1864–1909)
  1509. Minkowski, Rudolph Leo Bernhard (1895–1976)
  1510. Minnaert, Marcel Gilles Jozef (1893–1970)
  1511. Mira
  1512. Mira Variables
  1513. Miranda
  1514. Mirror
  1515. Mitchell, Maria (1818–89)
  1516. Mizar and Alcor
  1517. Möbius, August Ferdinand (1790–1868)
  1518. Molecule
  1519. Molonglo Observatory Synthesis Telescope
  1520. Molyneux, William (1656–98) and Molyneux, Samuel (1689–1728)
  1521. Monoceros
  1522. Montanari, Geminiano (1633–87)
  1523. Month
  1524. Moon
  1525. Moon Maps
  1526. Moore, Francis (1657–c. 1715)
  1527. Moore, Jonas (1627–79)
  1528. Moore, Patrick Alfred Caldwell (1923–)
  1529. Moreton Waves
  1530. Morgan, William Wilson (1906–94)
  1531. Morin, Jean-Baptiste (1583–1656)
  1532. Morley, Edward (1838–1923)
  1533. Morning Star
  1534. Moulton, Forest Ray (1872–1952)
  1535. Mount Graham International Observatory
  1536. Mount John University Observatory, New Zealand
  1537. Mount Stromlo and Siding Springs Observatories
  1538. Mount Wilson Observatory
  1539. Mouton, Gabriel (1618–94)
  1540. Moving Groups
  1541. Mullard Radio Astronomy Observatory
  1542. Mullard Space Science Laboratory
  1543. Multiple Mirror Telescope Observatory
  1544. Multiple Star
  1545. Multiple Stellar Systems: Types and Stability
  1546. Musca
  1547. Muses-C (Mu-launched Space Engineering Satellite)
  1548. n-Body Problem
  1549. Nadir
  1550. Naked-eye Astronomy
  1551. Nançay Radio Observatory
  1552. Napier [Napeir, Nepair, Nepeir, Neper, Napare, Naper, Naipper], John [Jhone] (1550–1617)
  1553. Narlikar, Jayant Vishnu (1938–)
  1554. NASA
  1555. NASA Infrared Telescope Facility
  1556. Nasir al-Din al-Tusi (1201–74)
  1557. Nasmyth Telescope
  1558. Nasmyth, James (1808–90)
  1559. National Astronomical Observatory, Japan
  1560. National Centre for Radio Astrophysics
  1561. National Radio Astronomy Observatory (NRAO), Tucson
  1562. National Research Council
  1563. National Solar Observatory
  1564. National Space Development Agency, Japan
  1565. Navigation
  1566. NEAR Shoemaker
  1567. Near-Earth Asteroids (NEAs)
  1568. Nearby Groups of Galaxies
  1569. Nebula
  1570. Nebulae: Observing by Amateurs
  1571. Needham, Joseph (1900–95)
  1572. Neptune
  1573. Neptune: Minor Satellites
  1574. Neptune: Rings
  1575. Neutral Point
  1576. Neutrino Astronomy
  1577. Neutrinos
  1578. Neutron
  1579. Neutron Stars
  1580. New General Catalog of Nebulae and Clusters of Stars (NGC)
  1581. Newcomb, Simon (1835–1909)
  1582. Newton
  1583. Newton’s Laws of Motion
  1584. Newtonian Telescope
  1585. Next Generation Space Telescope
  1586. NGC 1068: Prototypical Seyfert 2 Galaxy
  1587. NGC 4151
  1588. NGC 5128/Centaurus A: 150 Years of Wonder
  1589. Nicholas of Cusa [Nicolaus Cryffts, Chrypffs or Krebs, Nicolaus de Cusa, Cusanus] (1401–64)
  1590. Nicholson, Seth Barnes (1891–1963)
  1591. Nicolaus Copernicus
  1592. Nicolaus Copernicus Astronomical Center
  1593. Niels Bohr Institute for Astronomy, Physics and Geophysics
  1594. Nitrogen (N)
  1595. Nobel Prize Winners in Astronomy
  1596. Nobeyama Radio Observatory
  1597. Node
  1598. Non-gravitational Force
  1599. Non-radial Stellar Pulsations
  1600. Nordic Optical Telescope
  1601. Norma
  1602. North America Nebula (NGC 7000)
  1603. North American Indian Astronomy
  1604. Nostradamus (1503–66)
  1605. Nova V1974 Cygni
  1606. Novae
  1607. Novae: Amateur Discovery
  1608. Nozomi (Planet-B)
  1609. Nuclear Beta Decay
  1610. Nuclear Combustion
  1611. Nuclear Processing
  1612. Nuclear Properties
  1613. Nuclear Reactions Rates
  1614. Nucleosynthesis
  1615. Nuffield Radio Astronomy Laboratories
  1616. Numerical Simulation of Stellar Convection: Comparison with Mixing-length Theory
  1617. Nuñez Salaciense, Pedro [Nunes, Pedro; Nonius, Petrus] (1502–78)
  1618. Nutation
  1619. OB Associations
  1620. Oberon
  1621. Oberth, Hermann (1894–1989)
  1622. Objective Lens
  1623. Oblateness
  1624. Obliquity of the Ecliptic
  1625. Observatoire de Besançon
  1626. Observatoire de la Cîte d’Azur
  1627. Observatoire de Lyon
  1628. Observatoire de Marseille
  1629. Observatoire de Paris
  1630. Observatoire de Section de Meudon, Paris
  1631. Observatoire de Strasbourg
  1632. Observatoire des Sciences de l’Univers de Bordeaux
  1633. Observatoire des Sciences de l’Univers de Grenoble
  1634. Observatoire Royal de Belgique
  1635. Observatories and their Location
  1636. Observatories: History
  1637. Observatorio AstronĂłmico Nacional, Colombia
  1638. Observatorio AstronĂłmico Nacional, Mexico (OAN)
  1639. Observatorio del Roque de Los Muchachos
  1640. Observatorio del Teide
  1641. Observatory
  1642. Observing Asteroids
  1643. Observing Galaxies
  1644. Observing Gamma-Ray Bursters by Amateurs
  1645. Observing Globular Clusters
  1646. Observing Jupiter and its Satellites
  1647. Observing Meteors by Video and Image Intensifier
  1648. Observing the Moon by Amateurs
  1649. Obsevatoire d’Haute-Provence
  1650. Occultation
  1651. Oceans
  1652. Octans
  1653. Odierna [Hodierna], Gioanbatista [Giovan or Giovanni Battista] (1597–1660)
  1654. Oenopides of Chios (c. 500–c. 430 BC)
  1655. Ohio State University Radio Observatory
  1656. Okayama Astrophysical Observatory
  1657. Olbers, Heinrich Wilhelm (1758–1840)
  1658. Olbers’ Paradox
  1659. Oljato
  1660. Olympus Mons
  1661. Omega Nebula (M17, NGC 6618)
  1662. Ondrejov Observatory
  1663. Onsala Space Observatory
  1664. Oort Cloud
  1665. Oort, Jan Hendrik (1900–92)
  1666. Oosterhoff, P Th (1904–78)
  1667. Ophiuchus
  1668. Öpik (Opik), Ernst Julius (1893–1985)
  1669. Oppenheimer, Julius Robert (1904–67)
  1670. Oppolzer, Theodor Egon Ritter von (1841–86)
  1671. Opposition
  1672. Optical Astronomy
  1673. Optical Double
  1674. Optical Interferometers
  1675. Orbit
  1676. Orbital Elements
  1677. Orbiting Astronomical Observatory (OAO)
  1678. Orbiting Solar Observatory
  1679. Oresme, Nicole (1320–82)
  1680. Orientale Basin
  1681. Origin of The Solar System
  1682. Orion
  1683. Orion Arm
  1684. Orion Nebula (M42, NGC 1976)
  1685. Orionids
  1686. Orrery
  1687. Oscillating Universe
  1688. Osiander, Andreas (1498–1552)
  1689. Osservatorio Astronomico di Bologna
  1690. Osservatorio Astronomico di Brera
  1691. Osservatorio Astronomico di Roma
  1692. Outer Planets
  1693. Owens Valley Radio Observatory
  1694. Owl Nebula (M97, NGC 3587)
  1695. Oxygen (O)
  1696. Ozone Hole
  1697. Padova/Asiago Observatories
  1698. Palimpsest
  1699. Palitzsch, Johann Georg (1723–88)
  1700. Pallas
  1701. Palomar Observatory
  1702. Parabola
  1703. Parallaxes
  1704. Parker, Eugene [‘Gene’] Newman (1927–)
  1705. Parkes Observatory
  1706. Parsec (pc)
  1707. Parsons, Charles (1854–1931)
  1708. Particle Acceleration in Magnetic Fields
  1709. Particle Astrophysics
  1710. Particle Physics and Astronomy Research Council
  1711. Pauli Exclusion Principle
  1712. Pavo
  1713. Pawsey, Joseph Lade (1908–62)
  1714. Payne-Gaposchkin, Cecilia Helena [nee Payne] (1900–79)
  1715. Pease, Francis G (1881–1938)
  1716. Peculiar Galaxies
  1717. Peebles, Phillip James E (1935–)
  1718. Pegasus
  1719. Peiresc, Nicolas-Claude Fabri de (1580–1637)
  1720. Pelican Nebula (IC 5070)
  1721. Pension, Michael Victor (1943–90)
  1722. Penzias, Arno Allan (1933–)
  1723. Periapsis
  1724. Periastron
  1725. Perigee
  1726. Perihelion
  1727. Perrine, Charles Dillon (1867–1951)
  1728. Perseids
  1729. Perseus
  1730. Peurbach [Peuerbach, Purbach], Georg von (1423–61)
  1731. PG1159 Stars
  1732. Phaethon
  1733. Phase
  1734. Phases of the Moon
  1735. Philolaus of Tarentum or Croton (c. 480 BC-?)
  1736. Phobos
  1737. Phobos and Deimos
  1738. Phoenix
  1739. Photodissociation Regions
  1740. Photon
  1741. Physics of Molecules
  1742. Piazzi, Giuseppe (1746–1826)
  1743. Pic-du-Midi Observatory (Observatoire Midi-Pyrenees) (OMP)
  1744. Picard, Jean (1620–82)
  1745. Pickering, Edward Charles (1846–1919) and Pickering, William Henry (1858–1938)
  1746. Pictor
  1747. Pioneer Missions
  1748. Pioneer Venus Mission
  1749. Pipe Nebula (B59, B65–7, B79)
  1750. Pisces
  1751. Piscis Austrinus
  1752. Plage
  1753. Planck Surveyor
  1754. Planck, Max (1858–1947)
  1755. Planet
  1756. Planet X
  1757. Planetarium
  1758. Planetary Atmospheres
  1759. Planetary Exploration
  1760. Planetary Interiors
  1761. Planetary Ionospheres
  1762. Planetary Magnetospheres
  1763. Planetary Nebula Central Star Mass Loss/Winds
  1764. Planetary Nebulae
  1765. Planetary Rings
  1766. Planetary Society
  1767. Planetary Surfaces
  1768. Planetary Theory from Eudoxus to Copernicus
  1769. Planetesimal
  1770. Planetology
  1771. Planisphere
  1772. Plaskett, John Stanley (1865–1941)
  1773. Plaskett’s Star
  1774. Plasma
  1775. Plate-Measuring Machine
  1776. Plato (428–347 BC)
  1777. Plössl, Georg Simon (1794–1868)
  1778. Plough
  1779. Plutino
  1780. Pluto and Charon
  1781. Pluto–Kuiper Express
  1782. PoincarĂ©, Jules Henri (1854–1912)
  1783. Pointers
  1784. Polar
  1785. Polar Caps
  1786. Polar Motion and Length of Day
  1787. Polar Plumes
  1788. Polar Ring Galaxies
  1789. Polarimetry: Imaging Polarimetry
  1790. Polarimetry: Spectropolarimetry
  1791. Polaris
  1792. Polarization
  1793. Polarization in Active Galaxies
  1794. Pollux
  1795. Pond, John (1767–1836)
  1796. Pons, Jean-Louis (1761–1831)
  1797. Population I Stars
  1798. Population II Stars
  1799. Population III Stars
  1800. Porter, Russell (1871–1949)
  1801. Poseidonius of Apamea (c. 135–c. 50 BC)
  1802. Position Angle
  1803. Positron
  1804. Poynting–Robertson Effect
  1805. PoznaƄ Astronomical Observatory
  1806. Pre-main-sequence Binary Stars
  1807. Pre-main-sequence Stars
  1808. Precession
  1809. Prehistoric Astronomy
  1810. Primeval Fireball
  1811. Procyon
  1812. Profession
  1813. Prognoz
  1814. Prominence
  1815. Proper Motion
  1816. Proper Motion: Optical/Infrared
  1817. Protogalaxies
  1818. Proton
  1819. Proton
  1820. Protoplanet
  1821. Protoplanetary Disks
  1822. Protoplanetary Nebulae
  1823. Proxima Centauri
  1824. Ptolemaic System
  1825. Ptolemy
  1826. Pulsar Backends
  1827. Pulsars
  1828. Pulsating and Chemically Peculiar Upper Main Sequence Stars
  1829. Puppis
  1830. Purcell, Edward Mills (1912–)
  1831. Purple Mountain Observatory
  1832. Pushchino Radio Astronomy Observatory
  1833. Pythagoras of Samos (c. 580–c. 500 BC)
  1834. Pyxis
  1835. Qadi Zada, al’Rumi (1364–1436)
  1836. Quadrantids
  1837. Quadrature
  1838. Quantum Gravity
  1839. Quantum Mechanics
  1840. Quantum Theory
  1841. Quark
  1842. Quasar
  1843. Quasiperiodic Oscillations in X-ray Binaries
  1844. Quasistellar Objects: Intervening Absorption Lines
  1845. Quasistellar Objects: Intrinsic AGN Absorption Lines
  1846. Quasistellar Objects: Overview
  1847. Quasistellar Objects: Surveys
  1848. Quetelet, Lambert Adolphe (1796–1874)
  1849. R Coronae Borealis Stars
  1850. Radar Astronomy
  1851. Radial Velocities
  1852. Radiant
  1853. Radiation
  1854. Radiative Transfer
  1855. Radiatively Driven Stellar Winds from Hot Stars
  1856. Radio Astronomy for Amateurs
  1857. Radio Emission from Binary Stars
  1858. Radio Galaxy
  1859. Radio Instrumentation
  1860. Radio Interferometer
  1861. Radio Sources
  1862. Radio Telescope
  1863. Radio Telescope Data Path for Single Dish and Interferometers
  1864. Radioactivity
  1865. Radioastron (Spectrum-R)
  1866. Radioastronomical Institute, Ukraine
  1867. Radioastronomy
  1868. Ramsden, Jesse (1735–1800)
  1869. Ranger
  1870. Ray
  1871. Rayet, Georges Antoine Pons (1839–1906)
  1872. Rayleigh Limit
  1873. Reber, Grote (1911–2002)
  1874. Receivers: Millimeter and Longer-Wavelength Feeds and Receivers
  1875. Receivers: Submillimeter Feeds and Receivers
  1876. Red Dwarfs/Flare Stars
  1877. Red Giant Stars
  1878. Redman, Richard Oliver (1905–75)
  1879. Redshift
  1880. Rees, Sir Martin John (1942–)
  1881. Reeves, Hubert (1932–)
  1882. Reference Frames and Time Scales in General Relativity
  1883. Reflecting Telescopes
  1884. Reflection Nebulae
  1885. Reflector
  1886. Refracting Telescopes
  1887. Refractor
  1888. Regiomontanus [MĂŒller, Johann or Johannes] (1436–76)
  1889. Regolith
  1890. Regulus
  1891. Reiche, Maria (1903–98)
  1892. Reinhold, Erasmus (1511–53) and Reinhold, Erasmus (1538–92)
  1893. Relative Sunspot Number
  1894. Relict
  1895. Resolving Power
  1896. Resonance
  1897. Reticulum
  1898. Retrograde Motion
  1899. Revolution
  1900. Rhea
  1901. Rheticus [Rhaeticus; Lauchen, Georg Joachim von] (1514–74)
  1902. Riccioli, Giambattista [Giovanni Battista] (1598–1671)
  1903. Richard of Wallingford (1291/2–1336(?))
  1904. Richer, Jean (1630–96)
  1905. Rigel
  1906. Right Ascension (RA)
  1907. Rille
  1908. Ring Nebula (M57, NGC 6720)
  1909. Ritchey, George Willis (1864–1945)
  1910. Rittenhouse, David (1732–96) and Rittenhouse, Benjamin (1740–1825)
  1911. Robinson, Thomas Romney (1792–1882)
  1912. Roche Limit
  1913. Roche Lobe
  1914. Roche, Édouard Albert (1820–83)
  1915. Rockets in Astronomy
  1916. RĂžmer [Römer, Roemer], Ole [Olaf] Christensen (1644–1710)
  1917. Rooke, Lawrence (1622–62)
  1918. ROSAT (Röntgen Satellite)
  1919. Rosetta
  1920. Rosette Nebula (NGC 2237–39, 2246)
  1921. Rosse, 3rd Earl of [William Parsons, Lord Rosse, Lord Oxmantown] (1800–67) and Rosse, 4th Earl of [Laurence Parsons, Lord Rosse, Lord Oxmantown] (1840–1908)
  1922. Rossi X-ray Timing Explorer (RXTE/Explorer 69)
  1923. Rossi, Bruno Benedetto (1905–93)
  1924. Rotation
  1925. Royal Astronomical Society
  1926. Royal Astronomical Society of Canada
  1927. Royal Observatory, Edinburgh
  1928. Royal Observatory, Greenwich
  1929. RR Lyrae Stars
  1930. RS Canum Venaticorum
  1931. Rubin, Vera Cooper (1928–)
  1932. Rue, Warren de la (1815–89)
  1933. Runaway Star
  1934. Russell, Henry Norris (1877–1957)
  1935. Russian Astronomy
  1936. Russian Aviation and Space Agency
  1937. Rutherford Appleton Laboratory
  1938. Ryle, Sir Martin (1918–84)
  1939. Sabine, Sir Edward (1788–1883)
  1940. Sadler, Donald H (1908–87)
  1941. Sagan, Carl Edward (1934–96)
  1942. Sagitta
  1943. Sagittarius
  1944. Sagittarius A
  1945. Sagittarius Dwarf Galaxy
  1946. Saha, Meghnad (1893–1956)
  1947. Sakigake
  1948. Sakurai’s Object
  1949. Salpeter, Edwin Ernest (1924–)
  1950. Sampex (Small, Anomalous and Magnetospheric Particle Explorer)
  1951. San Fernando Observatory
  1952. Sandage, Allan Rex (1926–)
  1953. Saros
  1954. Sarpi, Paolo (1552–1623)
  1955. Satellite (Natural)
  1956. Saturn
  1957. Saturn and the Outer Gas Giants: Observing by Amateurs
  1958. Saturn Nebula (NGC 7009)
  1959. Saturn: Magnetosphere
  1960. Saturn: Magnetosphere Interaction with Titan
  1961. Saturn: Rings
  1962. Saturn: Satellites
  1963. Scaliger, Joseph (1540–1609)
  1964. Schall von Bell, Johann Adam (1592–1666)
  1965. Scheiner, Christoph (1575–1650)
  1966. Schiaparelli, Giovanni Virginio (1835–1910)
  1967. Schickard [Schickhardt], Wilhelm (1592–1635)
  1968. Schlesinger, Frank (1871–1943)
  1969. Schmidt Telescope
  1970. Schmidt-Cassegrain Telescope
  1971. Schmidt, Bernhard Voldemar (1879–1935)
  1972. Schmidt, Maarten (1929–)
  1973. Schopf, James William (1941–)
  1974. Schramm, David N (1945–97)
  1975. Schröter Effect
  1976. Schröter, Johann Hieronymous (1745–1816)
  1977. Schuster, Sir Arthur (1851–1934)
  1978. Schwabe, Samuel Heinrich (1789–1875)
  1979. Schwarzschild, Karl (1873–1916)
  1980. Schwarzschild, Martin (1912–97)
  1981. Scintillation
  1982. Scorpius
  1983. Scorpius X-1
  1984. Sculptor
  1985. Scutum
  1986. sdO Stars
  1987. Seares, Frederick Hanley (1873–1964)
  1988. Season
  1989. Secchi, Angelo (1818–78)
  1990. Second of Arc
  1991. Secondary Crater
  1992. Seeing
  1993. Selene (Selenological and Engineering Explorer)
  1994. Seleucus of Seleucia (c. 190 BC–?)
  1995. Self-Organized Criticality and Turbulence in the Solar System and Beyond
  1996. Separation
  1997. Serpens
  1998. SETI Institute
  1999. Severin [Soerensen, Longomontanus], Christian (1562–1647)
  2000. Sextans
  2001. Seyfert Galaxies
  2002. Seyfert, Carl K (1911–60)
  2003. Shakerley, Jeremy (1626–c. 1655)
  2004. Shanghai Astronomical Observatory
  2005. Shapley Concentration
  2006. Shapley, Harlow (1885–1972)
  2007. Shen Kua (1031–95)
  2008. Shepherd Moon
  2009. Shinsei
  2010. Shklovskii, losif Samuilovich (1916–85)
  2011. Shoemaker–Levy 9–Jupiter Collision
  2012. Shoemaker, Eugene [‘Gene’] Merle (1928–97) and Shoemaker, Carolyn [nĂ©e Spellman]
  2013. Short-period Comet
  2014. Sidereal Period
  2015. Sidereal Time
  2016. Siderite
  2017. Siderolite
  2018. Siderostat/heliostat/coelostat
  2019. SigĂŒenza y Gongora, Carlos de (1645−1700)
  2020. Sikhote Alin Meteorite
  2021. Sirius
  2022. Sitterly, Charlotte Emma Moore (1898−1990)
  2023. Skylab
  2024. Slipher, Vesto Melvin (1875−1969)
  2025. Sloan Digital Sky Survey
  2026. Small Astronomy Satellite (SAS)
  2027. Small Magellanic Cloud
  2028. Smart-1
  2029. Smith, Harlan James (1924–91)
  2030. Smith, Sir Francis Graham (1923–)
  2031. Smyth, Charles Piazzi [also Charles Piazzi-Smyth] (1819−1900)
  2032. SNC Meteorite
  2033. Snel [Snell or Snellius or Snel van Royen], Willebrord (1580−1626)
  2034. SociĂ©tĂ© Française d’Astronomie et d’Astrophysique
  2035. Software for Amateurs: Data Analysis
  2036. Software for Amateurs: Ephemeris and Sky Simulation
  2037. Software in Astronomy
  2038. Software: Digital Sky Surveys
  2039. Software: IRAF
  2040. Software: Radio Pulsar Software
  2041. Software: Stellar Photometry
  2042. SOHO (Solar and Heliospheric Observatory)
  2043. Solar Abundances
  2044. Solar Active Regions
  2045. Solar Active Regions: Ephemeral
  2046. Solar Activity Complexes
  2047. Solar Activity Indices
  2048. Solar Activity: Long-Term Records
  2049. Solar Atmosphere: Empirical Models
  2050. Solar Chromosphere: Ellerman Bombs
  2051. Solar Chromospheric Oscillations
  2052. Solar Chromospheric Plage
  2053. Solar Constant
  2054. Solar Corona: X-ray Bright Points
  2055. Solar Coronal Mass Ejection: Observations
  2056. Solar Coronal Mass Ejection: Theory
  2057. Solar Cycle
  2058. Solar Evolution
  2059. Solar Feeds
  2060. Solar Filament Channels
  2061. Solar Flare Classification
  2062. Solar Flare Forecasting
  2063. Solar Flare Magnetic Fields
  2064. Solar Flare Models
  2065. Solar Flare Observations
  2066. Solar Flares: Gamma Rays
  2067. Solar Flares: Impulsive Phase
  2068. Solar Flares: Main Phase
  2069. Solar Flares: Nonthermal Electrons
  2070. Solar Flares: Particle Acceleration Mechanisms
  2071. Solar Flares: Preflare Phase
  2072. Solar Flares: Radio Bursts
  2073. Solar Flares: Relation to Coronal Mass Ejections
  2074. Solar Flares: White Light
  2075. Solar Interior
  2076. Solar Interior: Convection Theory
  2077. Solar Interior: Convection Zone
  2078. Solar Interior: Convection Zone Flux Tubes
  2079. Solar Interior: Emerging Magnetic Flux Tubes
  2080. Solar Interior: Energy Generation
  2081. Solar Interior: Equation of State and Opacity
  2082. Solar Interior: Influence of Magnetic Fields
  2083. Solar Interior: Inversions of Helioseismic Data
  2084. Solar Interior: Local Helioseismology
  2085. Solar Interior: Neutrinos
  2086. Solar Interior: Rotation
  2087. Solar Interior: Solar Diameter, Oblateness and Temperature
  2088. Solar Interior: Standard Models
  2089. Solar Irradiance
  2090. Solar Magnetic Field
  2091. Solar Magnetic Field: Inference by Polarimetry
  2092. Solar Magnetic Field: Zeeman and Hanle Effects
  2093. Solar Magnetographs
  2094. Solar Maximum Mission (SMM)
  2095. Solar Photosphere
  2096. Solar Photosphere: Center-to-limb Variation
  2097. Solar Photosphere: Faculae
  2098. Solar Photosphere: Filigree
  2099. Solar Photosphere: Granulation
  2100. Solar Photosphere: Intranetwork and Turbulent Magnetic Fields
  2101. Solar Photosphere: Mesogranulation
  2102. Solar Photosphere: Supergranulation
  2103. Solar Photosphere: The Limb Effect and Gravitational Redshift
  2104. Solar Photospheric Magnetic Flux Tubes: Observations
  2105. Solar Photospheric Magnetic Flux Tubes: Theory
  2106. Solar Probe
  2107. Solar Prominence Chirality
  2108. Solar Prominence Eruption
  2109. Solar Prominence Fine Structure
  2110. Solar Prominence Formation
  2111. Solar Prominence Models
  2112. Solar Prominence Oscillations
  2113. Solar Prominences
  2114. Solar Prominences: Active
  2115. Solar Spectroscopy and Diagnostics
  2116. Solar Spectroscopy and Diagnostics: X-ray Emission
  2117. Solar Spectroscopy: Atomic Processes
  2118. Solar Spectroscopy: Coherent Plasma Emission
  2119. Solar Spectroscopy: Continuum Radio Emission and Diagnostics
  2120. Solar Spectroscopy: Infrared Emission
  2121. Solar Spectroscopy: Ultraviolet and Extreme Ultraviolet Emission
  2122. Solar Spectroscopy: Visible Emission
  2123. Solar System
  2124. Solar System: Dating of Events
  2125. Solar System: Exploration
  2126. Solar System: Formation
  2127. Solar System: Nomenclature
  2128. Solar System: Stability
  2129. Solar Telescopes and Instruments: Ground
  2130. Solar Telescopes and Instruments: Space
  2131. Solar Transition Region
  2132. Solar Wind
  2133. Solar Wind Acceleration
  2134. Solar Wind Composition
  2135. Solar Wind Plasma Waves
  2136. Solar Wind Shock Waves and Discontinuities
  2137. Solar Wind Turbulence
  2138. Solar Wind: Interplanetary Radio Bursts
  2139. Solar Wind: Coronal Origins
  2140. Solar Wind: Corotating Interaction Regions
  2141. Solar Wind: Energetic Particles
  2142. Solar Wind: Global Properties
  2143. Solar Wind: Interaction with Local Interstellar Medium
  2144. Solar Wind: Kinetic Properties
  2145. Solar Wind: Magnetic Field
  2146. Solar Wind: Manifestations of Solar Activity
  2147. Solar Wind: Radio Techniques for Probing
  2148. Solar Wind: Theory
  2149. Solar Wind: Ulysses
  2150. Solar Wind: Interaction with Comets
  2151. Solar X-ray Jets
  2152. Solar-B
  2153. Solar–Stellar Connection
  2154. Sola–Stellar Connection: Activity and Brightness Changes of Solar-Type Stars
  2155. Solar–Terrestrial Connection: Coupling Between Solar Wind, Magnetosphere, Ionosphere, and Neutral Atmosphere
  2156. Solar–Terrestrial Connection
  2157. Solar–Terrestrial Connection: Long-Term and Short-Term Climate Variability
  2158. Solar–Terrestrial Connection: Space Weather Predictions
  2159. SolarSoft
  2160. Solstices
  2161. Sombrero Galaxy
  2162. Somerville, Mary [nĂ©e Fairfax] (1780–1872)
  2163. Sosigenes of Alexandria (c. 50 or 90 BC–?)
  2164. South African Astronomical Observatory
  2165. South African Astronomical Observatory: from 1972 to the Present
  2166. South African Astronomy
  2167. South American Astronomy
  2168. South Pole–Aitken Basin (SPA Basin)
  2169. Space and Time References: Concepts
  2170. Space Geodesy
  2171. Space Infrared Telescope Facility (SIRTF)
  2172. Space Instrumentation: Astrometry
  2173. Space Instrumentation: Cosmic Backgrounds
  2174. Space Instrumentation: Imaging Interferometry
  2175. Space Interferometry Mission (SIM)
  2176. Space Probe
  2177. Space Research Institute
  2178. Space Research Organization Netherlands
  2179. Space Telescope European Coordinating Facility (ST-ECF)
  2180. Space Telescope Science Institute (STScI)
  2181. Space Velocity
  2182. Spacetime
  2183. Spanish Astronomy
  2184. Spartan (Shuttle Pointed Autonomous Research Tool for Astronomy)
  2185. Special Astrophysical Observatory, Russia
  2186. Special Relativity
  2187. Speckle Imaging of Binary Stars
  2188. Spectrographs: Fiber-fed Spectrographs
  2189. Spectrographs: High-Resolution Spectrographs
  2190. Spectrographs: Integral Field Units
  2191. Spectrographs: Low-Resolution Spectrographs
  2192. Spectrographs: Multislit Spectrographs
  2193. Spectroheliograph/spectrohelioscope
  2194. Spectroscope/spectrograph
  2195. Spectroscopic Binary Stars
  2196. Spectrum (pl: spectra)
  2197. Spectrum-X Gamma
  2198. Spencer Jones, Sir Harold (1890–1960)
  2199. Spherical Aberration
  2200. Spica
  2201. Spiral Arms
  2202. Spiral Galaxy
  2203. Spitzer, Lyman, Jr (1914–97)
  2204. Spole, Anders (1630–99)
  2205. Sporadic Meteor
  2206. Spörer, Gustav F W (1822–95)
  2207. Square Of Pegasus
  2208. Sripati (1019–66)
  2209. SS Cygni
  2210. SS433
  2211. St Andrews University Observatory
  2212. St Petersburg State University Astrophysical Observatory
  2213. Standard Model of Particle Physics
  2214. Star Clusters
  2215. Star Diagonal
  2216. Star Formation
  2217. Star Formation and Radio Emission from Normal Galaxies
  2218. Star of Bethlehem
  2219. Starburst Galaxies
  2220. Stardust
  2221. Steady-State Theory
  2222. Stebbins, Joel (1878–1966)
  2223. Stellar Activity
  2224. Stellar Astronomy (to the Rise of Astrophysics in the Mid-Nineteenth Century)
  2225. Stellar Atmospheres
  2226. Stellar Atmospheres: Cool Stars
  2227. Stellar Atmospheres: Early Type Stars
  2228. Stellar Diameters
  2229. Stellar Distributions
  2230. Stellar Dynamics
  2231. Stellar Evolution
  2232. Stellar Interiors
  2233. Stellar Interiors: Thermodynamics
  2234. Stellar Masses
  2235. Stellar N-body Systems: Dissipation
  2236. Stellar Nomenclature
  2237. Stellar Opacity
  2238. Stellar Photometry
  2239. Stellar Populations
  2240. Stellar Pulsation
  2241. Stellar Rotation on the Main Sequence
  2242. Stephan’s Quintet (NGC 7317, 7318A, 7318B, 7319, 7320)
  2243. Stereo Comparator
  2244. Steward Observatory
  2245. Stingray Nebula (Hen 1357)
  2246. Stokes, George Gabriel (1819–1903)
  2247. Stony Meteorite
  2248. Stony-iron Meteorite
  2249. Streete, Thomas (1622–89)
  2250. String Theory/Superstring Theory
  2251. Stromgren, Bengt (1908–87)
  2252. Structure and Evolution of the Sun and Stars, 1800–1955
  2253. Strutt, John William [Lord Rayleigh] (1842–1919)
  2254. Struve family
  2255. Struve, Gustav (1858–1920)
  2256. Struve, Karl (1854–1920)
  2257. Struve, Otto (1897–1963)
  2258. Struve, Otto Wilhelm (1819–1905)
  2259. Struve, Wilhelm (1793–1864)
  2260. Subaru Telescope, Hawaii
  2261. Subatomic Particles
  2262. Subbotin, Mikhail Fedorovich (1893–1966)
  2263. Submillimeter Telescope Observatory
  2264. Submillimeter Wave Astronomy Satellite (SWAS)
  2265. Sudbury Neutrino Observatory
  2266. Suess, Hans Eduard (1909–)
  2267. Suidas (tenth century)
  2268. Suisei
  2269. Summer Triangle
  2270. Sun
  2271. Sun and Solar–terrestrial Physics
  2272. Sun as a Star
  2273. Sun: Amateur Observing
  2274. Sun: Basic Properties
  2275. Sun: Safe Observation
  2276. Sundial
  2277. Sunspot Classification
  2278. Sunspot Cycle
  2279. Sunspot Evolution
  2280. Sunspot Magnetic Fields
  2281. Sunspot Models
  2282. Sunspot Oscillations and Seismology
  2283. Sunspot Penumbra: Structure and Activity
  2284. Sunspot Pores
  2285. Sunspot Umbra: Structure and Evolution
  2286. Sunspots
  2287. Sunspots: Evershed Effect
  2288. Sunspots: Moving Magnetic Features and Moat Flow
  2289. Sunspots: Wilson Effect
  2290. Sunyaev–Zeldovich Effect
  2291. Super-Kamiokande
  2292. Superclusters and the Local Supercluster
  2293. Superior Planets
  2294. Superluminal Motion
  2295. Supermassive Black Holes in Active Galactic Nuclei
  2296. Supermassive Black Holes in Inactive Galaxies
  2297. Supernova 1987A
  2298. Supernova Remnants
  2299. Supernovae
  2300. Supernovae: Amateur Discovery by CCD Imaging
  2301. Supernovae: Amateur Discovery by Eye
  2302. Supersymmetry
  2303. Surges
  2304. Surveyor
  2305. Swasey, Ambrose (1846–1937)
  2306. Swedish Space Corporation (SSC)
  2307. Symbiotic Stars
  2308. Synchronous Orbit
  2309. Synchronous Rotation
  2310. Synchrotron Radiation
  2311. Synodic Period
  2312. Synthetic Stellar Populations
  2313. Syrtis Major
  2314. Syzygy
  2315. T Tauri Stars
  2316. Talbot, William Henry Fox (1800–77)
  2317. Tarantula Nebula (NGC 2070)
  2318. Tarde, Jean (1561/2–1636)
  2319. Tartu Observatory
  2320. Tata Institute of Fundamental Research
  2321. Taurids
  2322. Taurus
  2323. Taylor, Joseph H (1941–)
  2324. Tebbutt, John (1834–1916)
  2325. Tectonics
  2326. Tektite
  2327. Telescope
  2328. Telescope Engineering
  2329. Telescope Mountings (for Amateur Astronomers)
  2330. Telescopes in History
  2331. Telescopes of the Future
  2332. Telescopes, Mounts and Control Systems
  2333. Telescopes, Reflecting: Large Telescopes for Amateurs
  2334. Telescopes: Control by Software for Amateurs
  2335. Telescopes: Reflecting — Use for Amateurs
  2336. Telescopes: Refracting, Use for Amateurs
  2337. Telescopes: Commercial Availability for Amateurs
  2338. Telescopium
  2339. Teller, Edward (1908–)
  2340. Tempel, Ernst Wilhelm Leberecht (1821–89)
  2341. Temperature Scales
  2342. Tenma (Astro-B)
  2343. Tenskwatawa (1768–1837)
  2344. Terminator
  2345. Terrestrial Coordinate Systems and Frames
  2346. Terrestrial Planets
  2347. Tethys
  2348. Thabit Ibn Qurra, Abu’l-Hasan (836–901)
  2349. Thales of Miletus (624–546 BC)
  2350. Tharsis Montes
  2351. The 2dF Galaxy Redshift Survey
  2352. The Colors of Stars
  2353. The Cosmological Constant and its Interpretation
  2354. Hubble Space Telescope: Technical Specifications
  2355. The Telescope (to 1950)
  2356. Thémis
  2357. Theodosius of Bithynia (c. 160–c. 100 BC)
  2358. Theon of Alexandria (c. 335–c. 395)
  2359. Thom, Alexander (1894–1945)
  2360. Thomson, William [Baron Kelvin of Largs] (1824–1907)
  2361. Three-body Problem
  2362. Thuban
  2363. Tibbon, Jacob ben Machir ibn [known as Prophatius] (1236–1312)
  2364. Tides
  2365. Time Scales: Atomic
  2366. Time Scales: Terrestrial
  2367. Timocharis (c. 280 BC)
  2368. Tisserand, François FĂ©lix (1845–96)
  2369. Titan
  2370. Titania
  2371. Titius, Johann Daniel (1729–96)
  2372. Tombaugh, Clyde William (1906–97)
  2373. Tompion, Thomas (c. 1639–1713)
  2374. Topological Defects in Cosmology
  2375. Torricelli, Evangelista (1608–47)
  2376. Torun Radio Astronomy Observatory
  2377. Towneley, Richard (1629–1707)
  2378. Townes, Charles Hard (1915–)
  2379. TRACE (Transition Region and Coronal Explorer)
  2380. Trans-Neptunian Object (TNO)
  2381. Transit
  2382. Transition Region Flows
  2383. Transition Region Models
  2384. Transition Region: Explosive Events
  2385. Transition Region: First Ionization Potential Effect
  2386. Trapezium
  2387. Triangulum
  2388. Triangulum Australe
  2389. Triangulum Galaxy
  2390. Trieste Astronomical Observatory
  2391. Trifid Nebula (M20, NGC 6514)
  2392. Triton
  2393. Trojan Asteroids
  2394. Troughton, Edward (1753–1836)
  2395. Trumpler, Robert Julius (1886–1956)
  2396. Tsiolkovsky [Ciolkovskij, Ziolkowski], Konstantin Eduardovich [Eduardowitsch] (1857–1935)
  2397. Tucana
  2398. Tully–Fisher Relation
  2399. Tunable Imaging Filters
  2400. Tunguska Event
  2401. Tuorla Observatory
  2402. Turner, Herbert Hall (1861–1930)
  2403. Twilight Glow
  2404. Tycho (Crater)
  2405. Tycho Brahe (1546–1601)
  2406. Tycho Star Catalogs: The 2.5 Million Brightest Stars
  2407. Tycho’s Star
  2408. Tychonic System
  2409. U Gem Stars
  2410. Uhuru (SAS-1/Explorer 42)
  2411. Ultraviolet Astronomy
  2412. Ulugh Beg (1394–1449)
  2413. Umbriel
  2414. Uncertainty Principle
  2415. United Kingdom Infrared Telescope
  2416. Universal Distance Scale
  2417. Universal Time (UT)
  2418. Universe
  2419. Universe: Simulations of Structure and Galaxy Formation
  2420. Universe: Thermal History
  2421. UniversitÀt Radioastronomisches Institut, Bonn
  2422. University Observatory, Ludwig-Maximilians-UniversitÀt
  2423. University of Crete Observatory
  2424. University of Hawaii Institute for Astronomy
  2425. University of Tokyo, Institute of Astronomy
  2426. Unsöld, Albrecht (1905–95)
  2427. Uppsala Astronomical Observatory
  2428. Uranus
  2429. Uranus and Neptune: Atmospheres, Ionospheres, and Magnetospheres
  2430. Uranus: Rings
  2431. Urey, Harold Clayton (1893–1981)
  2432. Ursa Major
  2433. Ursa Minor
  2434. US Astronomy
  2435. US Naval Observatory
  2436. Ussher, James (1581–1656)
  2437. Valles Marineris
  2438. Valongo Observatory
  2439. Van Allen Belts
  2440. Van Allen, James (1914–)
  2441. van de Kamp, Peter (1901–95)
  2442. van Maanen, Adriaan (1884–1947)
  2443. Van Maanen’s Star
  2444. Van Vleck Observatory
  2445. Variable Stars
  2446. Variable Stars: Amateur Observation of Eruptive Variables
  2447. Vatican Observatory
  2448. Vega
  2449. VEGA Space Mission
  2450. Vela
  2451. Vela Pulsar
  2452. Vela Supernova Remnant
  2453. Velikovsky, Immanuel (1895–1979)
  2454. Venera (Missions)
  2455. Venus
  2456. Venus: Atmosphere
  2457. Venus: Interaction with Solar Wind
  2458. Venus: Surface
  2459. Verbiest, Ferdinand (1623–88)
  2460. Very Large Array, National Radio Astronomy Observatory
  2461. Very-high-energy Gamma-ray Sources
  2462. Vesta
  2463. Viking Mission
  2464. Vilnius University Observatory
  2465. Virgo
  2466. Virgo A
  2467. Virgo Cluster
  2468. Virgo Gravitational-wave Interferometer (VIRGO)
  2469. Visual Binary Stars
  2470. VLBI (Very Long Baseline Interferometry)
  2471. Vogel, Hermann Carl (1841–1907)
  2472. Voids
  2473. Volans
  2474. Volcanism in the Solar System
  2475. Voyager Mission
  2476. Vulcan
  2477. Vulpecula
  2478. W M Keck Observatory
  2479. Wallenquist, Åke Anders Edvard (1904–94)
  2480. Ward, Seth (1617–89)
  2481. Warner & Swasey Observatory
  2482. Warner, Worcester Reed (1846–1929)
  2483. Water Cycle
  2484. Wave–Particle Duality
  2485. Wavelength
  2486. Wegener, Alfred Lothar (1880–1930)
  2487. Weight
  2488. Weizmann Institute of Science
  2489. Werner, Johann (1468–1522)
  2490. Westerbork Synthesis Radio Telescope
  2491. Whipple, Fred Lawrence (1906–)
  2492. Whirlpool Galaxy
  2493. Whiston, William (1667–1752)
  2494. White Dwarfs
  2495. White Dwarfs in the Galaxy’s Halo
  2496. Whitford, Albert Edward (1905–)
  2497. Whittaker, Edmund Taylor (1873–1956)
  2498. Whole Earth Telescope (WET)
  2499. Wide-Field Astrophotography
  2500. Widefield CCD Imagers
  2501. WidmanstÀtten Pattern
  2502. WidmanstĂ€tten, Alois von Beckh-[Alois Beck, Edler von WidmanstĂ€tten] (1753/4–1849)
  2503. Wien, Wilhelm (1864–1928)
  2504. Wilcox Solar Observatory
  2505. Wilkins, John (1614–72)
  2506. Wilson, Alexander (1714–86)
  2507. Wilson, Olin Chaddock (1909–94)
  2508. Wilson, Robert Woodrow (1936–)
  2509. WIMPs and MACHOs
  2510. Wind
  2511. Wing, Vincent (1619–68)
  2512. Winthrop, John (1714–79)
  2513. Wise Observatory
  2514. Wittich, Paul (c. 1546–86)
  2515. WIYN Observatory
  2516. Wolf–Rayet Nebula
  2517. Wolf–Rayet Stars
  2518. Wolf, Charles J E (1827–1918)
  2519. Wolf, Johann Rudolf (1816–93)
  2520. Wolf, Max[imilian] Franz Joseph Cornelius (1863–1932)
  2521. Wollaston, William (1766–1828)
  2522. Woolley, Richard van der Riet (1906–86)
  2523. Wormhole
  2524. Wren, Sir Christopher (1632–1723)
  2525. Wright, Thomas (1711–86)
  2526. Wrinkle Ridge
  2527. X-Ray Astronomy
  2528. X-ray Binary Stars
  2529. X-Ray Bursters
  2530. X-Ray Telescopes
  2531. X-rays
  2532. Xenocrates of Chalcedon (396–314 BC)
  2533. Xenophanes of Colophon (c. 570–c. 480 BC)
  2534. XEUS (X-ray Evolving Universe Spectroscopy Mission)
  2535. Newton Mission
  2536. Yarkovsky Effect
  2537. Year
  2538. Yerkes Observatory
  2539. Yohkoh
  2540. Young Stellar Objects
  2541. Young, Thomas (1773–1829)
  2542. Yunus, Abu’l-Hasan ibn (950–1009)
  2543. Z Andromedae (Z And)
  2544. Zach, Baron Franz Xaver von (1754–1832)
  2545. Zeeman Effect
  2546. Zeeman, Pieter (1865–1943)
  2547. Zeiss, Carl (1816–88)
  2548. Zel’dovich [Zeldovich, Seldowitsch], Yakov Borisovich (1914–87)
  2549. Zenith
  2550. Zenith Distance
  2551. Zenithal Hourly Rate (ZHR)
  2552. Zeno of Elea (c. 490–c. 425 BC)
  2553. Zero Gravity
  2554. Zhang Heng [Chang Heng] (78–139)
  2555. Zhu Xi [Chu-hsi] (1130–1200)
  2556. Zodiacal Light
  2557. Zodiacal Stars
  2558. Zöllner, Johann Karl [Carl] Friedrich (1834–82)
  2559. Zond
  2560. Zucchi, Niccolo (1586–1670)
  2561. Zwicky, Fritz (1898–1974)
  2562. ZZ Ceti Stars

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