Astronomy, SAR-SPA

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.
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Astronomy Encyclopedia Articles By Title

saros
saros, in astronomy, interval of 18 years 1113 days (1013 days when five leap years are included) after which the......
satellite
satellite, natural object (moon) or spacecraft (artificial satellite) orbiting a larger astronomical body. Most......
satellite observatory
satellite observatory, Earth-orbiting spacecraft that allows celestial objects and radiation to be studied from......
Saturn
Saturn, in space exploration, any of a series of large two- and three-stage vehicles for launching spacecraft,......
Saule
Saule, in Baltic religion and mythology, the sun goddess, who determines the well-being and regeneration of all......
Savitskaya, Svetlana Yevgenyevna
Svetlana Yevgenyevna Savitskaya is a Soviet cosmonaut who was the first woman to walk in space. The daughter of......
Schiaparelli, Giovanni Virginio
Giovanni Virginio Schiaparelli was an Italian astronomer and senator whose reports of groups of straight lines......
Schickard, Wilhelm
Wilhelm Schickard was a German astronomer, mathematician, and cartographer. In 1623, he invented one of the first......
Schirra, Wally
Wally Schirra was a U.S. astronaut who flew the Mercury Sigma 7 (1962) and was command pilot of Gemini 6 (1965),......
Schlesinger, Frank
Frank Schlesinger was an American astronomer who pioneered in the use of photography to map stellar positions and......
Schmidt telescope
Schmidt telescope, telescope in which a spherical primary mirror receives light that has passed through a thin......
Schmidt, Brian P.
Brian P. Schmidt is an astronomer who was awarded the 2011 Nobel Prize for Physics for his discovery of dark energy,......
Schmidt, Maarten
Maarten Schmidt was a Dutch-born American astronomer whose identification of the wavelengths of the radiation emitted......
Schmitt, Harrison
Harrison Schmitt is an American geologist, astronaut, and politician who was part of the Apollo space program’s......
schreibersite
schreibersite, mineral consisting of iron nickel phosphide [(Fe,Ni)3P] that is present in most meteorites containing......
Schwabe, Samuel Heinrich
Samuel Heinrich Schwabe was an amateur German astronomer who discovered that sunspots vary in number in a cycle......
Schwarzschild radius
Schwarzschild radius, the radius below which the gravitational attraction between the particles of a body must......
Schwarzschild, Karl
Karl Schwarzschild was a German astronomer whose contributions, both practical and theoretical, were of primary......
Science and Technology Satellite
Science and Technology Satellite (STSAT), any of a series of South Korean satellites, of which STSAT-2C was the......
Scientific Revolution
Scientific Revolution, drastic change in scientific thought that took place during the 16th and 17th centuries.......
Scorpius
Scorpius, in astronomy, zodiacal constellation lying in the southern sky between Libra and Sagittarius, at about......
Scorpius X-1
Scorpius X-1, (catalog number Sco X-1), brightest X-ray source in the sky, the first such object discovered in......
Scott, David
David Scott is a U.S. astronaut who was the commander of the Apollo 15 mission to the Moon. After graduation from......
Sculptor
Sculptor, constellation in the southern sky at about 1 hour right ascension and 30° south in declination. Its brightest......
Scutum
Scutum, constellation in the southern sky at about 19 hours right ascension and 10° south in declination. Its brightest......
Seasat
Seasat, experimental U.S. ocean surveillance satellite launched June 26, 1978. During its 99 days of operation,......
Secchi, Pietro Angelo
Pietro Angelo Secchi was an Italian Jesuit priest and astrophysicist, who made the first survey of the spectra......
Sedna
Sedna, small body in the outer solar system that may be the first discovered object from the Oort cloud. Sedna......
seeing
seeing, in astronomy, sharpness of a telescopic image. Seeing is dependent upon the degree of turbulence in the......
Sefer Yetzira
Sefer Yetzira, (Hebrew: “Book of Creation”), oldest known Hebrew text on white magic and cosmology; it contends......
Selene
Selene, in Greek and Roman religion, the personification of the moon as a goddess. She was worshipped at the new......
Serapis
Serapis, Greco-Egyptian deity of the Sun first encountered at Memphis, where his cult was celebrated in association......
Serpens
Serpens, the only constellation divided into two parts, Serpens Caput (Latin: “Head of the Serpent”) and Serpens......
SETI
SETI, ongoing effort to seek intelligent extraterrestrial life. SETI focuses on receiving and analyzing signals......
Sextans
Sextans, constellation at about 10 hours right ascension and on the celestial equator in declination. It is a faint......
Seyfert galaxy
Seyfert galaxy, any of a class of galaxies known to have active nuclei. Such galaxies were named for the American......
Shapash
Shapash, (“Light of the Gods”), in ancient Mesopotamian religion, sun goddess. In the cycle of myths recovered......
Shapley, Harlow
Harlow Shapley was an American astronomer who deduced that the Sun lies near the central plane of the Milky Way......
Sharma, Rakesh
Rakesh Sharma is an Indian military pilot and cosmonaut, the first Indian citizen in space. In 1970 Sharma joined......
Sharman, Helen
Helen Sharman is a British chemist and astronaut who was the first British citizen to go into space, participating......
Shaula
Shaula, second brightest star in the constellation Scorpius (after Antares) and the 24th brightest star in the......
Shavit
Shavit, Israeli launch vehicle. Shavit (Hebrew for “comet”) is a small three-stage solid-fueled rocket, first launched......
Sheikh Muszaphar Shukor
Sheikh Muszaphar Shukor is a Malaysian orthopedic surgeon who became the first Malaysian to go into space. Sheikh......
Shen Kuo
Shen Kuo was a Chinese astronomer, mathematician, and high official whose famous work Mengxi bitan (“Brush Talks......
Shenzhou
Shenzhou, any of a series of Chinese spacecraft, the fifth flight of which carried the first Chinese astronaut......
Shepard, Alan B., Jr.
Alan B. Shepard, Jr. was the first U.S. astronaut to travel in space. Shepard graduated from the U.S. Naval Academy,......
Shinsei
Shinsei, first Japanese scientific satellite, launched on Sept. 28, 1971. Shinsei observed solar radio emissions,......
Shoemaker, Carolyn
Carolyn Shoemaker was an American astronomer who became an expert at identifying comets. With her husband, Gene......
Shoemaker, Gene
Gene Shoemaker was an American astrogeologist who—along with his wife, Carolyn Shoemaker, and David H. Levy—discovered......
Short, James
James Short was a British optician and astronomer who produced the first truly parabolic—hence nearly distortionless—mirrors......
Shripati
Shripati was an Indian astronomer-astrologer and mathematician whose astrological writings were particularly influential.......
Shukla, Shubhanshu
Shubhanshu Shukla is an Indian astronaut who is part of the Gaganyaan program, which will send India’s first astronauts......
Shuttleworth, Mark
Mark Shuttleworth is a South African entrepreneur, philanthropist, and space tourist who became the first South......
sidereal period
sidereal period, the time required for a celestial body within the solar system to complete one revolution with......
siderostat
siderostat, any of a class of astronomical instruments consisting of a flat mirror that is turned slowly by a motor......
Sima Qian
Sima Qian was an astronomer, calendar expert, and the first great Chinese historian. He is most noted for his authorship......
Sin
Sin, in Mesopotamian religion, the god of the moon. Sin was the father of the sun god, Shamash (Sumerian: Utu),......
Sirius
Sirius, brightest star in the night sky, with apparent visual magnitude −1.46. It is a binary star in the constellation......
Sitter, Willem de
Willem de Sitter was a Dutch mathematician, astronomer, and cosmologist who developed theoretical models of the......
sizes of the planets
The solar system has two main types of planets. The inner planets—Mercury, Venus, Earth, and Mars—have rocky compositions.......
Skylab
Skylab, first U.S. space station, launched into Earth orbit on May 14, 1973. Three successive crews of visiting......
Slayton, Donald Kent
Donald Kent Slayton was an American astronaut who was one of the original seven Project Mercury astronauts in 1959......
Slipher, Vesto
Vesto Slipher was an American astronomer whose systematic observations (1912–25) of the extraordinary radial velocities......
small body
small body, any natural solar system object other than the Sun and the major planets and dwarf planets and their......
SMART-1
SMART-1, first lunar probe of the European Space Agency. SMART-1 was launched on Sept. 27, 2003. The 367-kg (809-pound)......
Smoot, George F.
George F. Smoot is an American physicist, who was corecipient, with John C. Mather, of the Nobel Prize for Physics......
Snell, Willebrord
Willebrord Snell was a Dutch astronomer and mathematician who discovered the law of refraction (also known as Snell’s......
Sol
Sol, in Roman religion, name of two distinct sun gods at Rome. The original Sol, or Sol Indiges, had a shrine on......
Solar and Heliospheric Observatory
Solar and Heliospheric Observatory (SOHO), satellite managed jointly by the European Space Agency (ESA) and the......
solar calendar
solar calendar, any dating system based on the seasonal year of approximately 365 14 days, the time it takes the......
solar constant
solar constant, the total radiation energy received from the Sun per unit of time per unit of area on a theoretical......
solar cycle
solar cycle, period of about 11 years in which fluctuations in the number and size of sunspots and solar prominences......
Solar Dynamics Observatory
Solar Dynamics Observatory (SDO), U.S. satellite designed to study the Sun. It was launched on February 11, 2010,......
solar eclipse
solar eclipse, the Moon coming between Earth and the Sun so that the Moon’s shadow sweeps over Earth’s surface.......
solar energy
solar energy, radiation from the Sun capable of producing heat, causing chemical reactions, or generating electricity.......
solar flare
solar flare, sudden intense brightening in the solar corona, usually in the vicinity of a magnetic inversion near......
solar nebula
solar nebula, gaseous cloud from which, in the so-called nebular hypothesis of the origin of the solar system,......
solar neutrino problem
solar neutrino problem, long-standing astrophysics problem in which the amount of observed neutrinos originating......
solar prominence
solar prominence, dense cloud of incandescent ionized gas projecting from the Sun’s chromosphere into the corona.......
solar radiation
solar radiation, electromagnetic radiation, including X-rays, ultraviolet and infrared radiation, and radio emissions,......
solar system
solar system, assemblage consisting of the Sun—an average star in the Milky Way Galaxy—and those bodies orbiting......
Solar Terrestrial Relations Observatory
Solar Terrestrial Relations Observatory (STEREO), two U.S. spacecraft that were designed to observe the Sun from......
solar wind
solar wind, flux of particles, chiefly protons and electrons together with nuclei of heavier elements in smaller......
solar wind power satellite
solar wind power satellite, large hypothetical satellite that would harvest energy from solar wind. A stream of......
Solovyov, Anatoly Yakovlevich
Anatoly Yakovlevich Solovyov is a Soviet cosmonaut who flew into space five times and holds the record for the......
solstice
solstice, either of the two moments in the year when the Sun’s apparent path is farthest north or south from Earth’s......
Somerville, Mary
Mary Somerville was a British science writer whose influential works synthesized many different scientific disciplines.......
Sosigenes of Alexandria
Sosigenes of Alexandria was a Greek astronomer and mathematician, probably from Alexandria, employed by Julius......
sounding rocket
sounding rocket, any unmanned rocket that is designed to probe atmospheric conditions and structure at heights......
South African National Space Agency
South African National Space Agency (SANSA), South African space agency that was founded to develop a national......
Southern African Large Telescope
Southern African Large Telescope (SALT), largest telescope in the Southern Hemisphere, with a mirror measuring......
Soyuz
Soyuz, any of several versions of Soviet/Russian crewed spacecraft launched since 1967 and the longest-serving......
space debris
space debris, artificial material that is orbiting Earth but is no longer functional. This material can be as large......
space elevator
space elevator, a concept for lifting mass out of Earth’s gravity well without using rockets in which an extremely......
space law
space law, the body of regulations in international law that governs conduct in and related to areas of space above......
space shuttle
space shuttle, partially reusable rocket-launched vehicle designed to go into orbit around Earth, to transport......
space station
space station, an artificial structure placed in orbit and having the pressurized enclosure, power, supplies, and......
space weather
space weather, conditions in space caused by the Sun that can affect satellites and technology on Earth as well......

Astronomy Encyclopedia Articles By Title