Astronomy, STA-TRA
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
Star cluster
Star cluster, either of two general types of stellar assemblages held together by the mutual gravitational attraction......
Stardust/NExT
Stardust/NExT, a U.S. space probe that captured and returned dust grains from interplanetary space and from a comet.......
Starliner
Starliner, crewed spacecraft built by the American corporation Boeing. Starliner consists of a conical Crew Module......
Starship
Starship, spacecraft being developed by the American corporation SpaceX. Starship, with the Super Heavy launch......
Steady-state theory
Steady-state theory, in cosmology, a view that the universe is always expanding but maintaining a constant average......
Stellar association
Stellar association, a very large, loose grouping of stars that are of similar spectral type and relatively recent......
Stellar classification
Stellar classification, scheme for assigning stars to types according to their temperatures as estimated from their......
Stony iron meteorite
Stony iron meteorite, any meteorite containing substantial amounts of both rocky material (silicates) and nickel-iron......
Stony meteorite
Stony meteorite, any meteorite consisting largely of rock-forming (silicate) minerals. Stony meteorites, which......
Strategic Defense Initiative
Strategic Defense Initiative (SDI), proposed U.S. strategic defensive system against potential nuclear attacksâas......
Stratospheric Observatory for Infrared Astronomy
Stratospheric Observatory for Infrared Astronomy (SOFIA), a Boeing 747 jet aircraft that carries a 2.5-metre (8.2-foot)......
Strekalov, Gennady Mikhailovich
Gennady Mikhailovich Strekalov was a Soviet and Russian cosmonaut who flew five times in space over a period of......
string theory
string theory, in particle physics, a theory that attempts to merge quantum mechanics with Albert Einsteinâs general......
Struve, Friedrich Georg Wilhelm von
Friedrich Georg Wilhelm von Struve was one of the greatest 19th-century astronomers and the first in a line of......
Struve, Otto
Otto Struve was a Russian-American astronomer known for his contributions to stellar spectroscopy, notably the......
Strömgren, Bengt
Bengt Strömgren was a Danish astrophysicist who pioneered the present-day knowledge of the gas clouds in space.......
Subaru Telescope
Subaru Telescope, a Japanese 8.2-metre (27-foot) optical-infrared telescope located on the dormant volcano Mauna......
Sullivan, Kathryn
Kathryn Sullivan is an American oceanographer and astronaut who in 1984 became the first American woman to walk......
Summer solstice
Summer solstice, the two moments during the year when the path of the Sun in the sky is farthest north in the Northern......
Sun
Sun, star around which Earth and the other components of the solar system revolve. It is the dominant body of the......
- Introduction
- Core, Radiation, Layers
- Evolution, Structure, Radiation
- Solar Atmosphere, Radiation, Core
- Chromosphere, Corona, Solar Flares
- Corona, Solar Wind, Radiation
- Solar Activity, Radiation, Coronal Mass Ejections
- Prominences, Solar Flares, Coronal Mass Ejections
- Flares, Solar Activity, Coronal Mass Ejections
- Solar Activity, Radiation, Atmosphere
- Astronomy, Heliophysics, Observations
Sunlight
Sunlight, solar radiation that is visible at Earthâs surface. The amount of sunlight is dependent on the extent......
Sunspot
Sunspot, vortex of gas on the surface of the Sun associated with strong local magnetic activity. Spots look dark......
Sunyaev, Rashid
Rashid Sunyaev is a Russian-German astrophysicist who, with Soviet physicist Yakov Zeldovich, first proposed the......
Super-Earth
Super-Earth, type of planet that is between about 2 to 10 times the mass of Earth. Some astronomers use a size......
Supercluster
Supercluster, a group of galaxy clusters typically consisting of 3 to 10 clusters and spanning as many as 200,000,000......
Supergiant star
Supergiant star, any star of very great intrinsic luminosity and relatively enormous size, typically several magnitudes......
supergravity
supergravity, a type of quantum field theory of elementary subatomic particles and their interactions that is based......
Supermassive black hole
Supermassive black hole (SMBH), a black hole more than one hundred thousand times the mass of the Sun. Nearly every......
Supermoon
Supermoon, a full moon that occurs when the Moon is at perigee (the closest point to Earth in its orbit). The Moon......
Supernova
Supernova, any of a class of violently exploding stars whose luminosity after eruption suddenly increases many......
Supernova 1987A
Supernova 1987A, first supernova observed in 1987 (hence its designation) and the nearest to Earth in more than......
Supernova remnant
Supernova remnant, nebula left behind after a supernova, a spectacular explosion in which a star ejects most of......
Surveyor
Surveyor, any of a series of seven unmanned U.S. space probes sent to the Moon between 1966 and 1968 to photograph......
Surya
Surya, in Hinduism, both the Sun and the Sun god. Although in the Vedic period (1500â5th century bce) several other......
Suzaku
Suzaku, is a Japanese-U.S. satellite observatory designed to observe celestial X-ray sources. Suzaku was launched......
Svarozhich
Svarozhich, in Slavic religion, god of the sun, of fire, and of the hearth. He was worshiped in a temple at Radegast......
Swedenborg, Emanuel
Emanuel Swedenborg was a Swedish scientist, Christian mystic, philosopher, and theologian who wrote voluminously......
Swift
Swift, U.S. satellite observatory designed to swing into the proper orientation to catch the first few seconds......
Swigert, Jack
Jack Swigert was a U.S. astronaut and command module pilot on the Apollo 13 mission (April 11â17, 1970), in which......
Swings, Pol
Pol Swings was a Belgian astrophysicist noted for his spectroscopic studies of the composition and structure of......
synchrotron radiation
synchrotron radiation, electromagnetic energy emitted by charged particles (e.g., electrons and ions) that are......
Synodic period
Synodic period, the time required for a body within the solar system, such as a planet, the Moon, or an artificial......
Syrtis Major
Syrtis Major, distinctive dark marking on the surface of the planet Mars, centred near 290° W and 10° N, which......
T Tauri star
T Tauri star, any of a class of very young stars having a mass of the same order as that of the Sun. So called......
Taenite
Taenite, nickel-iron mineral having a face-centred cubic structure and playing a major role in the crystallization......
Tamayo MĂ©ndez, Arnaldo
Arnaldo Tamayo MĂ©ndez is a Cuban pilot and cosmonaut. He was the first Latin American, the first person of African......
Tarantula Nebula
Tarantula Nebula, (catalog number NGC 2070) immense ionized-hydrogen region in the Large Magellanic Cloud, a satellite......
Tarter, Jill
Jill Tarter is an American astronomer known for her work in the search for extraterrestrial intelligence (SETI).......
Taurus
Taurus, in astronomy, zodiacal constellation lying in the northern sky between Aries and Gemini, between about......
Taurus-Littrow Valley
Taurus-Littrow Valley, region on the Moon where the Apollo 17 lunar mission landed. Located at 22° N 31° E, it......
Telescope
Telescope, device used to form magnified images of distant objects. The telescope is undoubtedly the most important......
Telescopes: Seeing Stars
Recently the worldâs largest single-dish radio telescope was completed in China. The Five-hundred-metre Aperture......
Telescopium
Telescopium, constellation in the southern sky at about 19 hours right ascension and 50° south in declination.......
Telstar
Telstar, series of communications satellites whose successful launching, beginning in 1962, inaugurated a new age......
Tereshkova, Valentina
Valentina Tereshkova is a Soviet cosmonaut and the first woman to travel into space. On June 16, 1963, she was......
Tethys
Tethys, major regular moon of Saturn, remarkable for a fissure that wraps around the greater part of its circumference.......
Thales of Miletus
Thales of Miletus was a philosopher renowned as one of the legendary Seven Wise Men, or Sophoi, of antiquity. He......
Tharsis
Tharsis, extensive volcanic province on Mars that contains three of the planetâs most massive volcanoes. The province......
The Fermi Paradox: Where Are All the Aliens?
On a clear night, staring up at the stars induces a sense of simultaneous wonder and insignificance. Humanity time......
The First Space Walk
On March 18, 1965, cosmonaut Aleksey Leonov rocketed into Earth orbit and exited his spacecraft, becoming the first......
The life cycle of a star
Stars begin their life cycle in molecular clouds. These clouds contain dense clumps of gas and dust, which can......
The New Space Race
In the first decades of the 21st century, a new space race emerged between India, China, and Japan. This infographic......
The Solar Eclipse That Made Albert Einstein a Science Celebrity
In February 1919 two teams of astronomers from the Greenwich and Cambridge observatories set out for Sobral, Brazil,......
The Sun Was Eaten: 6 Ways Cultures Have Explained Eclipses
Without a scientific explanation, the darkening of the Sun (or Moon) during an eclipse would be a startling event,......
THEMIS
THEMIS, five U.S. satellites that studied variations in the aurora. The spacecraft were launched by the National......
Thirsk, Robert
Robert Thirsk is the first Canadian astronaut to make a long-duration spaceflight. Thirsk received bachelorâs and......
Thor rocket
Thor rocket, missile initially developed by the U.S. Air Force as an intermediate-range ballistic missile. It was......
Thorne, Kip
Kip Thorne is an American physicist who was awarded the 2017 Nobel Prize for Physics for his work on the Laser......
Thoth
Thoth, in Egyptian religion, a god of the moon, of reckoning, of learning, and of writing. He was held to be the......
Three Worlds According to King Ruang
Three Worlds According to King Ruang, 14th-century cosmology that is the oldest known full-length text written......
Three-body problem
Three-body problem, in astronomy, the problem of determining the motion of three celestial bodies moving under......
Tiangong
Tiangong, any of a series of three Chinese space stations, the first of which was launched on September 29, 2011.......
Tidal friction
Tidal friction, in astronomy, strain produced in a celestial body (such as the Earth or Moon) that undergoes cyclic......
tide
tide, any of the cyclic deformations of one astronomical body caused by the gravitational forces exerted by others.......
Timeline of the Apollo Space Missions
Apollo was a project conducted by the U.S. National Aeronautics and Space Administration (NASA) in the 1960s and......
Timeline of the Space Race, 1957â69
This infographic presents a timeline of space-related achievements by the U.S.S.R. and the U.S. between 1957 and......
TIROS
TIROS, any of a series of U.S. meteorological satellites, the first of which was launched on April 1, 1960. The......
Tisserand, FĂ©lix
FĂ©lix Tisserand was a French astronomer noted for his textbook TraitĂ© de mĂ©canique cĂ©leste, 4 vol. (1889â96; âTreatise......
Titan
Titan, the largest moon of Saturn and the only moon in the solar system known to have clouds and a dense atmosphere.......
Titan rocket
Titan rocket, any of a series of U.S. rockets that were originally developed as intercontinental ballistic missiles......
Titania
Titania, largest of the moons of Uranus. It was first detected telescopically in 1787 by the English astronomer......
Titius, Johann Daniel
Johann Daniel Titius was a Prussian astronomer, physicist, and biologist whose law (1766) expressing the distances......
Tito, Dennis
Dennis Tito is an American businessman who became the first private individual to pay for his own trip into space.......
Titov, Gherman Stepanovich
Gherman Stepanovich Titov was a Soviet cosmonaut who piloted the Vostok 2 spacecraft, launched on August 6, 1961,......
Today in HistoryâFebruary 18: From Kansas to the Kuiper Belt
The butterfly effect, Midwest edition: A hailstorm in Kansas helped lead to the discovery of the dwarf planet Pluto.......
Today in HistoryâFebruary 27: The Discovery of Solar Radio Waves
On this day in 1942 a British physicist made a monumental discoveryâŠand couldnât tell anyone. British radar equipment......
Today in HistoryâJanuary 16: âThirty-Five New GuysââSix of Whom Were Women
On this day in 1978 NASA made an announcement: It had recruited the first new class of astronauts in almost a decade.......
Today in HistoryâJanuary 28: A Dark Day in Space Exploration
The night before the Challenger space shuttle was slated to take off on its 10th mission, a cold wave swept through......
Today in HistoryâJanuary 7: This Will Really Pull You In
Black holes sound like science fiction: collapsed stars whose incomprehensibly powerful gravitational pull absorbs......
Today in HistoryâJanuary 8: The Mysterious Sighting at Trans-en-Provence
In the long span of UFO sightings, which range from obvious hoaxes to truly unexplained phenomena, the Trans-en-Provence......
Today in HistoryâJuly 20: First Contact with a Hazardous Surface
On this day in 1969, the Apollo 11 mission put men on the Moon. As Neil Armstrongâs boots made contact with the......
Today in HistoryâJuly 23: NASA Discovers an Earthlike Planet
On this day in 2015, NASA announced the discovery of Earthâs âbigger, older cousin,â an exoplanet named Kepler-452b.......
Today in HistoryâJuly 8: A Local Newspaper Kicks Off Roswellâs UFO Mania
On July 7, 1947, soldiers at the Roswell Army Air Field (RAAF) in New Mexico recovered the remains of a flying......
Today in HistoryâJune 18: The First American Woman in Space
STS-7, which launched on this day in 1983, was one of the first operational space shuttle flights. On paper, it......
Today in HistoryâMarch 10: The Day the Planets Alignedâand the World Didnât End
On this day in 1982, every planet in the solar system aligned on one side of the Sunâand we braced for the world......
Today in HistoryâNovember 3: A Dog Is Launched into Space
On this day in 1957, the first earthling launched into orbit around our planet. (We donât count the fruit flies......
Tombaugh, Clyde
Clyde Tombaugh was an American astronomer who discovered Pluto in 1930 after a systematic search for a ninth planet......
Transit
Transit, in astronomy, the passage of a relatively small body across the disk of a larger body, usually a star......
Transit
Transit, any of the first series of U.S. navigation satellites. Launched by the U.S. Navy from 1960 to 1988, the......
Transit of Mercury
On Monday, May 9, 2016, viewers on Earth can see a transit of Mercury, in which that planet crosses in front of......