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44 Nysa
Nysa ( minor planet designation: 44 Nysa) is a large and very bright main-belt asteroid, and the brightest member of the Nysian asteroid family. It is classified as a rare class E asteroid and is probably the largest of this type (though 55 Pandora is only slightly smaller). Discovery It was discovered by Hermann Goldschmidt on May 27, 1857, and named after the mythical land of Nysa in Greek mythology. Physical properties In 2002 Kaasalainen ''et al.'' used 63 lightcurves from the Uppsala Asteroid Photometric Catalog (UAPC) to construct a shape model of 44 Nysa. The shape model is conical, which they interpreted as indicating the asteroid may actually be a contact binary. In 2003, Tanga ''et al.'' published results obtained from the Fine Guidance Sensor on the Hubble Space Telescope in which high-precision interferometry was performed on Nysa with the goal of a more accurate shape determination. Due to Hubble's orbit around the Earth, hours-long photometry sessions, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lightcurve
In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequency interval or band. Light curves can be periodic, as in the case of eclipsing binaries, Cepheid variables, other periodic variables, and transiting extrasolar planets, or aperiodic, like the light curve of a nova, a cataclysmic variable star, a supernova or a microlensing event or binary as observed during occultation events. The study of the light curve, together with other observations, can yield considerable information about the physical process that produces it or constrain the physical theories about it. Variable stars Graphs of the apparent magnitude of a variable star over time are commonly used to visualise and analyse their behaviour. Although the categorisation of variable star types is increasingly done from their spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versatile, renowned both as a vital research tool and as a public relations boon for astronomy. The Hubble telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories. The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting data, while the Goddard Space Flight Center (GSFC) controls the spacecraft. Hubble features a mirror, and its five main instruments observe in the ultraviolet, visible, and near-infrared regions of the electromagnetic spectrum. Hubble's orbit outside the distortion of Earth's atmosphere allows it to capture extremely high-resolution images with substantially lower background light than ground-based telescopes. It has recorded some of the most detaile ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hungaria Family
The Hungaria asteroids, also known as the Hungaria group, are a dynamical group of asteroids in the asteroid belt which orbit the Sun with a semi-major axis (longest radius of an ellipse) between 1.78 and 2.00 astronomical units (AU). They are the innermost dense concentration of asteroids in the Solar System—the near-Earth asteroids are much more sparse—and derive their name from their largest member 434 Hungaria. The Hungaria group includes the Hungaria family (), a collisional asteroid family which dominates its population. Description The Hungaria asteroids typically share the following orbital parameters: * Semi-major axis between 1.78 and 2.00 AU * Orbital period of approximately 2.5 years * Low eccentricity of below 0.18 * An inclination of 16° to 34° * Approximate mean-motion resonance with Jupiter of 9:2, and with Mars of 2:3 The 4:1 resonance Kirkwood gap (at 2.06 AU) marks the outer boundary of the Hungaria family, while interactions with Mars determine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aubrite
Aubrites are a group of meteorites named for Aubres, a small achondrite meteorite that fell near Nyons, France, in 1836. They are primarily composed of the orthopyroxene enstatite and are often called enstatite achondrites. Their igneous origin separates them from primitive enstatite achondrites and means they originated in an asteroid. Aubrites are typically light-colored with a brownish fusion crust. Most aubrites are heavily brecciated; they are often said to look "lunar" in origin. Aubrites are primarily composed of large white crystals of the Fe-poor, Mg-rich orthopyroxene, or enstatite, with minor phases of olivine, nickel-iron metal, and troilite, indicating a magmatic formation under extremely reducing conditions. The severe brecciation of most aubrites attests to a violent history for their parent body. Since some aubrites contain chondritic xenoliths, it is likely that the aubrite parent body collided with an asteroid of “F-chondritic” composition. Comparisons of au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
624 Hektor
624 Hektor is the largest Jupiter trojan and the namesake of the Hektor family, with a highly elongated shape equivalent in volume to a sphere of approximately 225 to 250 kilometers diameter. It was discovered on 10 February 1907, by astronomer August Kopff at Heidelberg Observatory in southwest Germany, and named after the Trojan prince Hector, from Greek mythology. It has one small 12-kilometer sized satellite, Skamandrios, discovered in 2006. Description ''Hektor'' is a D-type asteroid, dark and reddish in colour. It lies in Jupiter's leading Lagrangian point, , called the Greek camp after one of the two sides in the legendary Trojan War. Hektor is named after the Trojan hero Hektor and is thus one of two trojan asteroids that is "misplaced" in the wrong camp (the other one being 617 Patroclus in the Trojan camp). Contact-binary hypothesis Hektor is one of the most elongated bodies of its size in the Solar System, being approximately 403 km in its longest dim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
43 Ariadne
Ariadne (minor planet designation: 43 Ariadne) is a fairly large and bright main-belt asteroid. It is the second-largest member of the Flora asteroid family. It was discovered by N. R. Pogson on 15 April 1857 and named after the Greek heroine Ariadne. Characteristics Ariadne is very elongate (almost twice as long as its smallest dimension) and probably bi-lobed or at least very angular. It is a retrograde rotator, although its pole points almost parallel to the ecliptic towards ecliptic coordinates (β, λ) = (−15°, 253°) with a 10° uncertainty. This gives an axial tilt of about 105°. Studies 43 Ariadne was in a study of asteroids using the Hubble FGS. Asteroids studied include (63) Ausonia, (15) Eunomia, (43) Ariadne, (44) Nysa, and (624) Hektor. Trivia * For reasons unknown, "Asteroid 43 Ariadne" was included in a list of names of supporters of the NASA spacecraft Stardust that was stored on a microchip within the spacecraft. * The maximum apparent size of Ariad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
15 Eunomia
Eunomia (minor planet designation 15 Eunomia) is a very large asteroid in the inner asteroid belt. It is the largest of the stony ( S-type) asteroids, with 3 Juno as a close second. It is quite a massive asteroid, in 6th to 8th place (to within measurement uncertainties). It is the largest Eunomian asteroid, and is estimated to contain 1% of the mass of the asteroid belt. Eunomia was discovered by Annibale de Gasparis on July 29, 1851, and named after Eunomia, one of the Horae (Hours), a personification of order and law in Greek mythology. Characteristics As the largest S-type asteroid (with 3 Juno being a very close second), Eunomia has attracted a moderate amount of scientific attention. Eunomia appears to be an elongated but fairly regularly shaped body, with what appear to be four sides of differing curvature and noticeably different average compositions. Its elongation led to the suggestion that Eunomia may be a binary object, but this has been refuted. It is a retrog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
63 Ausonia
Ausonia ( minor planet designation: 63 Ausonia) is a stony Vestian asteroid from the inner region of the asteroid belt, approximately 100 kilometers (60 miles) in diameter. It was discovered by Italian astronomer Annibale de Gasparis on 10 February 1861, from the Astronomical Observatory of Capodimonte, in Naples, Italy. The initial choice of name for the asteroid was "Italia", after Italy, but this was modified to Ausonia, an ancient classical name for the Italian region. left, Lightcurve-based 3D-model of ''Ausonia'' Orbit and classification ''Ausonia'' is a member of the Vesta family. Vestian asteroids have a composition akin to cumulate eucrites (HED meteorites) and are thought to have originated deep within 4 Vesta's crust, possibly from the Rheasilvia crater, a large impact crater on its southern hemisphere near the South pole, formed as a result of a subcatastrophic collision. Vesta is the main belt's second-largest and second-most-massive body after Ceres. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fine Guidance Sensor (HST)
Fine Guidance Sensor (FGS) for the Hubble Space Telescope is a system of three instruments used for pointing the telescope in space, and also for astrometry and its related sciences. Each FGS uses a combination of optics and electronics to provide for pointing the telescope at a certain location in the sky. There are three Hubble FGS, and they have been upgraded over the lifetime of the telescope by manned Space Shuttle missions. The instruments can support pointing of 2 milli-arc seconds (units of degree). The three FGS are part of the Hubble Space Telescope's ''Pointing Control System'', aka PCS.http://www.stsci.edu/hst/fgs/documents/papers/spie.pdf The FGS function in combination with the Hubble main computer and gyroscopes, with the FGS providing data to the computer as sensors which enables the HST to track astronomical targets. The FGS can be used to locate something in space, and then lock-on to it. It can provide the movements the telescope must make to keep the objec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sky, night, but their immense distances from Earth make them appear as fixed stars, fixed points of light. The most prominent stars have been categorised into constellations and asterism (astronomy), asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye, all within the Milky Way galaxy. A star's life star formation, begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Its stellar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occultation
An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks from view (occults) an object in the background. In this general sense, occultation applies to the visual scene observed from low-flying aircraft (or computer-generated imagery) when foreground objects obscure distant objects dynamically, as the scene changes over time. If the closer body does not entirely conceal the farther one, the event is called a ''transit''. Both transit and occultation may be referred to generally as ''occlusion''; and if a shadow is cast onto the observer, it is called an eclipse. The symbol for an occultation, and especially a solar eclipse, is file:Occultation symbol.svg (U+1F775 🝵). Occultations by the Moon The term occultation is most frequently used to describe lunar occultations, those relativ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polarization (waves)
Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. A simple example of a polarized transverse wave is vibrations traveling along a taut string ''(see image)''; for example, in a musical instrument like a guitar string. Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string. In contrast, in longitudinal waves, such as sound waves in a liquid or gas, the displacement of the particles in the oscillation is always in the direction of propagation, so these waves do not exhibit polarization. Transverse waves that exhibit polarization include electromagnetic waves such as light and radio waves, gravitational waves, and transverse sound waves (shear waves) in solids. An electromagnetic wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
