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Double Helix Nebula
The Double Helix Nebula is a gaseous nebula in the direction of the constellation Ophiuchus, near the center of our galaxy. It is thought to have been distorted by magnetic torsion into the shape of two connected spirals, known as a double helix, which is akin to the shape of a DNA molecule. There are infrared-luminous stars contained in the nebula that are red-giants and other supergiant stars. There are other stars contained within, but are mostly too dim to be observed. The nebula was discovered by the Spitzer Space Telescope. The segment seen so far is thought to be 80 light years long, 300 light years from the supermassive black hole thought to be at the galaxy's center, and 25,000 light years from Earth. This nebula is seen as circumstantial evidence that the magnetic fields at the center of the galaxy are extremely strong, more than 1,000 times stronger than those of the Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spitzer Space Telescope
The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, following IRAS (1983) and ISO (1995–1998). It was the first spacecraft to use an Earth-trailing orbit, later used by the Kepler planet-finder. The planned mission period was to be 2.5 years with a pre-launch expectation that the mission could extend to five or slightly more years until the onboard liquid helium supply was exhausted. This occurred on 15 May 2009. Without liquid helium to cool the telescope to the very low temperatures needed to operate, most of the instruments were no longer usable. However, the two shortest-wavelength modules of the IRAC camera continued to operate with the same sensitivity as before the helium was exhausted, and continued to be used into early 2020 in the Spitzer Warm Mission. During the warm mission, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J2000
In astronomy, an epoch or reference epoch is a instant, moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a Astronomical object, celestial body, as they are subject to Perturbation (astronomy), perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or Perihelion and aphelion, aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities. The applied tools of the disciplines of celestial mechanics or its subfield orbital mechanics (for predicting orbital paths and positions for bodies in motion under the gravitational effects of other bodi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophiuchus
Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellation Serpens. Ophiuchus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. An old alternative name for the constellation was Serpentarius (). Location Ophiuchus lies between Aquila, Serpens, Scorpius, Sagittarius, and Hercules, northwest of the center of the Milky Way. The southern part lies between Scorpius to the west and Sagittarius to the east. In the northern hemisphere, it is best visible in summer. It is opposite of Orion. Ophiuchus is depicted as a man grasping a serpent; the interposition of his body divides the snake constellation Serpens into two parts, Serpens Caput and Serpens Cauda. Ophiuchus straddles the equator with the majority ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nebula
A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. In these regions, the formations of gas, dust, and other materials "clump" together to form denser regions, which attract further matter, and eventually will become dense enough to form stars. The remaining material is then thought to form planets and other planetary system objects. Most nebulae are of vast size; some are hundreds of light-years in diameter. A nebula that is visible to the human eye from Earth would appear larger, but no brighter, from close by. The Orion Nebula, the brightest nebula in the sky and occupying an area twice the angular diameter of the full Moon, can be viewed with the naked eye but was missed by early astronomers. Although denser than the space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milky Way Galaxy
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term ''Milky Way'' is a translation of the Latin ', from the Greek ('), meaning "milky circle". From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies. The Milky Way is a barred spiral galaxy with an estimated D25 isophotal diameter of , but only about 1,000 light years thick at the spiral arms (more at the bulge) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torsion (mechanics)
In the field of solid mechanics, torsion is the twisting of an object due to an applied torque. Torsion is expressed in either the pascal (Pa), an SI unit for newtons per square metre, or in pounds per square inch (psi) while torque is expressed in newton metres (N·m) or foot-pound force (ft·lbf). In sections perpendicular to the torque axis, the resultant shear stress in this section is perpendicular to the radius. In non-circular cross-sections, twisting is accompanied by a distortion called warping, in which transverse sections do not remain plane. For shafts of uniform cross-section unrestrained against warping, the torsion is: : T = \frac \tau= \frac G \varphi where: * ''T'' is the applied torque or moment of torsion in Nm. * \tau (tau) is the maximum shear stress at the outer surface * ''J''T is the torsion constant for the section. For circular rods, and tubes with constant wall thickness, it is equal to the polar moment of inertia of the section, but for other shape ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double Helix
A double is a look-alike or doppelgänger; one person or being that resembles another. Double, The Double or Dubble may also refer to: Film and television * Double (filmmaking), someone who substitutes for the credited actor of a character * ''The Double'' (1934 film), a German crime comedy film * ''The Double'' (1971 film), an Italian film * ''The Double'' (2011 film), a spy thriller film * ''The Double'' (2013 film), a film based on the Dostoevsky novella * '' Kamen Rider Double'', a 2009–10 Japanese television series ** Kamen Rider Double (character), the protagonist in a Japanese television series of the same name Food and drink * Doppio, a double shot of espresso * Dubbel, a strong Belgian Trappist beer or, more generally, a strong brown ale * A drink order of two shots of hard liquor in one glass * A "double decker", a hamburger with two patties in a single bun Games * Double, action in games whereby a competitor raises the stakes ** , in contract bridge ** Doubl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 (one million million, or billion in long scale). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year (365.25 days). Because it includes the time-measurement word "year", the term ''light-year'' is sometimes misinterpreted as a unit of time. The ''light-year'' is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years) which derives from astrometry; it is the distance at which one astronomical unit subtends an angle of one second of arc. Defini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supermassive Black Hole
A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions of times the mass of the Sun (). Black holes are a class of astronomical objects that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, not even light. Observational evidence indicates that almost every large galaxy has a supermassive black hole at its Central massive object, center. For example, the Milky Way has a Galactic Center#Supermassive black hole, supermassive black hole in its Galactic Center, corresponding to the Astronomical radio source, radio source Sagittarius A*. Accretion (astrophysics), Accretion of Interstellar medium, interstellar gas onto supermassive black holes is the process responsible for powering Active galactic nucleus, active galactic nuclei (AGNs) and quasars. Two supermassive black holes have been directly imaged by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface is made up of the ocean, dwarfing Earth's polar ice, lakes, and rivers. The remaining 29% of Earth's surface is land, consisting of continents and islands. Earth's surface layer is formed of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's liquid outer core generates the magnetic field that shapes the magnetosphere of the Earth, deflecting destructive solar winds. The atmosphere of the Earth consists mostly of nitrogen and oxygen. Greenhouse gases in the atmosphere like carbon dioxide (CO2) trap a part of the energy from the Sun close to the surface. Water vapor is widely present in the atmosphere and forms clouds that cover most of the planet. More solar e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emission Nebulae
An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. Among the several different types of emission nebulae are H II regions, in which star formation is taking place and young, massive stars are the source of the ionizing photons; and planetary nebulae, in which a dying star has thrown off its outer layers, with the exposed hot core then ionizing them. General information Usually, a young star will ionize part of the same cloud from which it was born, although only massive, hot stars can release sufficient energy to ionize a significant part of a cloud. In many emission nebulae, an entire cluster of young stars is contributing energy. Stars that are cooler than around 25,000K don't give off enough ultraviolet radiation with wavelengths shorter than 91.2nm (the wavelength needed in order to ionize Hydrogen atoms). This results in the re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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