Astronomy, PAR-REG
Human beings have long been fascinated by the celestial sphere above, whose twinkling lights have inspired not only scientific theories but also many artistic endeavors. Humankind's fascination with the world beyond Earth has led to many landmark moments in history, as when space exploration took a giant step forward with the advent of technology that allowed humans to successfully travel to the Moon and to build spacecraft capable of exploring the rest of the solar system and beyond.
Astronomy Encyclopedia Articles By Title
Paris Observatory, national astronomical observatory of France, under the direction of the Academy of Sciences.......
Viktor Ivanovich Patsayev was a Soviet cosmonaut. He served as design engineer on the Soyuz 11 mission, in which......
Pavo, constellation in the southern sky at about 20 hours right ascension and 65° south in declination. Its brightest......
Julie Payette is a Canadian astronaut and engineer who was named the 29th governor-general of Canada (2017–21).......
Cecilia Payne-Gaposchkin was a British-born American astronomer who discovered that stars are made mainly of hydrogen......
Tim Peake is a British astronaut and military officer who in 2016, while on a mission to the International Space......
James Peebles is a Canadian-born American physicist who was awarded the 2019 Nobel Prize for Physics for his work......
Pegasus, constellation in the northern sky at about 23 hours right ascension and 20° north in declination. Its......
Pegasus, any of a series of three U.S. scientific satellites launched in 1965. These spacecraft were named for......
Benjamin Peirce was an American mathematician, astronomer, and educator who computed the general perturbations......
Nicolas-Claude Fabri de Peiresc was a French antiquary, humanist, and influential patron of learning who discovered......
penumbra, (from Latin paene, “almost”; umbra, “shadow”), in astronomy, the outer part of a conical shadow cast......
Arno Penzias was a German American astrophysicist who shared one-half of the 1978 Nobel Prize for Physics with......
Saul Perlmutter is an American physicist who was awarded the 2011 Nobel Prize for Physics for his discovery of......
Charles Dillon Perrine was a U.S. astronomer who discovered the sixth and seventh moons of Jupiter in 1904 and......
From August 11 to 14, 2015, the Northern Hemisphere sky will be lit up by the Perseid meteor shower. This year......
Perseus, constellation in the northern sky at about 4 hours right ascension and 40° north in declination. With......
perturbation, in astronomy, deviation in the motion of a celestial object caused either by the gravitational force......
Georg von Peuerbach was an Austrian mathematician and astronomer instrumental in the European revival of the technical......
phase, in astronomy, any of the varying appearances of a celestial body as different amounts of its disk are seen......
Pherecydes of Syros was a Greek mythographer and cosmogonist traditionally associated with the Seven Wise Men of......
Phobos, the inner and larger of Mars’s two moons. It was discovered telescopically with its companion moon, Deimos,......
Phobos-Grunt, Russian spacecraft that was designed to land on the Martian moon Phobos and bring some of its soil......
Phoebe, midsize irregular moon of Saturn, discovered by the American astronomer William Henry Pickering in 1899......
Phoenix, constellation in the southern sky at about 1 hour right ascension and 50° south in declination. Its brightest......
Phoenix, U.S. space probe launched by the National Aeronautics and Space Administration (NASA) on Aug. 4, 2007;......
photometry, in astronomy, the measurement of the brightness of stars and other celestial objects (nebulae, galaxies,......
photosphere, visible surface of the Sun, from which is emitted most of the Sun’s light that reaches Earth directly.......
Giuseppe Piazzi was an Italian astronomer who discovered (January 1, 1801) and named the first asteroid, or “minor......
Jean Picard was a French astronomer who first accurately measured the length of a degree of a meridian (longitude......
Edward Charles Pickering was a U.S. physicist and astronomer who introduced the use of the meridian photometer......
William Hayward Pickering was a New Zealand-born American engineer, physicist, and head of the team that developed......
William Henry Pickering was a U.S. astronomer who discovered Phoebe, the ninth satellite of Saturn. In 1891 Pickering......
Pictor, constellation in the southern sky at about 6 hours right ascension and 60° south in declination. Its brightest......
Pioneer, any of the first series of unmanned U.S. space probes designed chiefly for interplanetary study. Whereas......
Pisces, in astronomy, zodiacal constellation in the northern sky between Aries and Aquarius, at about 1 hour right......
Piscis Austrinus, constellation in the southern sky at about 22 hours right ascension and 30° south in declination.......
Planck, a European Space Agency satellite, launched on May 14, 2009, that measured the cosmic microwave background......
planet, (from Greek planētes, “wanderers”), broadly, any relatively large natural body that revolves in an orbit......
Planet Nine, hypothetical ninth planet in the far reaches of the solar system, further from the Sun than Neptune,......
planetarium, theatre devoted to popular education and entertainment in astronomy and related fields, especially......
planetary defense, the detection of asteroids and comets whose impact with Earth could significantly affect the......
planetary nebula, any of a class of bright nebulae that are expanding shells of luminous gas expelled by dying......
planetary ring, a disklike aggregation of particles and larger objects that orbit a planet’s equator. The planetary......
planetesimal, one of a class of bodies that are theorized to have coalesced to form Earth and the other planets......
John Stanley Plaskett was a Canadian astronomer remembered for his expert design of instruments and his extensive......
Pleiades, (catalog number M45), open cluster of young stars in the zodiacal constellation Taurus, about 440 light-years......
Pleione, star in the Pleiades, thought to be typical of the shell stars, so called because in their rapid rotation......
Pluto, large, distant member of the solar system that formerly was regarded as the outermost and smallest planet.......
Henri Poincaré was a French mathematician, one of the greatest mathematicians and mathematical physicists at the......
Siméon-Denis Poisson was a French mathematician known for his work on definite integrals, electromagnetic theory,......
polar motion, a periodic rotation of the Earth’s spin axis about a mean axis, somewhat like the wobble of a spinning......
Polaris, Earth’s present northern polestar, or North Star, at the end of the “handle” of the so-called Little Dipper......
polestar, the brightest star that appears nearest to either celestial pole at any particular time. Owing to the......
Pollux, brightest star in the zodiacal constellation Gemini. A reddish giant star, it has an apparent visual magnitude......
Valery Vladimirovich Polyakov was a Russian cosmonaut who holds the record for the longest single spaceflight in......
John Pond was the sixth astronomer royal of England, who organized the Royal Greenwich Observatory to an efficiency......
Marcos Pontes is a Brazilian pilot and astronaut, the first Brazilian citizen in space. Pontes graduated in 1984......
Pavel Popovich was a Soviet cosmonaut who piloted the Vostok 4 spacecraft, launched August 12, 1962. He and Andriyan......
Populations I and II, in astronomy, two broad classes of stars and stellar assemblages defined in the early 1950s......
Praesepe, (catalog numbers NGC 2632 and M 44), open, or galactic, cluster of about 1,000 stars in the zodiacal......
Procyon, brightest star in the northern constellation Canis Minor (Lesser Dog) and one of the brightest in the......
proper motion, in astronomy, the apparent motion of a star across the celestial sphere at right angles to the observer’s......
Prospero, the first and only Earth satellite launched by Great Britain. It was launched with a British Black Arrow......
protogalaxy, in cosmology, vast cloud of gas that by contraction and condensation becomes a galaxy of stars. In......
Proton, Russian launch vehicle used for both government and commercial payloads. Since 1965 the Proton launch vehicle......
protoplanet, in astronomical theory, a hypothetical eddy in a whirling cloud of gas or dust that becomes a planet......
Proxima Centauri is the closest star to the Sun, about 4.2 light-years away in the Alpha Centauri system. As a......
Dumitru Prunariu is a Romanian pilot and cosmonaut who was the first Romanian citizen in space. Prunariu earned......
PSR 1257+12, pulsar around which the first extrasolar planets were discovered in 1992. PSR 1257+12 itself was discovered......
Psyche, name of both a metal-rich asteroid and the U.S. spacecraft that is scheduled to orbit it beginning in August......
Ptolemaic system, mathematical model of the universe formulated by the Alexandrian astronomer and mathematician......
Ptolemy was an Egyptian astronomer, mathematician, and geographer of Greek descent who flourished in Alexandria......
Pulkovo Observatory, astronomical observatory founded in 1839 near St. Petersburg, Russia. Its founder and first......
pulsar, any of a class of cosmic objects, the first of which were discovered through their extremely regular pulses......
Puppis, constellation in the southern sky at about 8 hours right ascension and 30° south in declination. Its brightest......
Pyxis, constellation in the southern sky at about 9 hours right ascension and 30° south in declination. Its brightest......
Qian Xuesen was a Chinese engineer and research scientist widely recognized as the “father of Chinese aerospace”......
quadrature, in astronomy, that aspect of a heavenly body in which its direction as seen from the Earth makes a......
quasar, an astronomical object of very high luminosity found in the centres of some galaxies and powered by gas......
Didier Queloz is a Swiss astronomer who was awarded the 2019 Nobel Prize for Physics for his discovery with Swiss......
Adolphe Quetelet was a Belgian mathematician, astronomer, statistician, and sociologist known for his application......
R Coronae Borealis star, any of a small group of old stars of the class called peculiar variables (see variable......
R Monocerotis, (catalog number NGC 2261), stellar infrared source and nebula in the constellation Monoceros (Greek:......
R-7, Soviet/Russian missile and launch vehicle. Under the direction of the rocket pioneer Sergey Korolyov, the......
radio and radar astronomy, study of celestial bodies by examination of the radio-frequency energy they emit or......
radio interferometer, apparatus consisting of two or more separate antennas that receive radio waves from the same......
radio jet, material spewing from the centres of some galaxies at close to the speed of light and emitting strong......
radio source, in astronomy, any of various objects in the universe that emit relatively large amounts of radio......
radio telescope, astronomical instrument consisting of a radio receiver and an antenna system that is used to detect......
Ranger, any of a series of nine unmanned probes launched from 1961 to 1965 by the United States National Aeronautics......
Ras Algethi, red supergiant star, whose diameter is nearly twice that of Earth’s orbit. It lies in the constellation......
Re, in ancient Egyptian religion, god of the Sun and creator god. He was believed to travel across the sky in his......
Grote Reber was an American astronomer and radio engineer who built the first radio telescope and was largely responsible......
red dwarf star, the most numerous type of star in the universe and the smallest type of hydrogen-burning star.......
redshift, displacement of the spectrum of an astronomical object toward longer (red) wavelengths. It is attributed......
Martin Rees is an English cosmologist and astrophysicist who was a main expositor of the big-bang theory of the......
reflection nebula, interstellar cloud that would normally be a dark nebula (or molecular cloud) but whose dust......
Regiomontanus was the foremost mathematician and astronomer of 15th-century Europe, a sought-after astrologer,......
Regulus, brightest star in the zodiacal constellation Leo and one of the brightest in the entire sky, having an......