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(144898) 2004 VD17
(144898) , provisional designation , is a sub-kilometer asteroid, classified as near-Earth object of the Apollo group once thought to have a low probability of impacting Earth on 4 May 2102. It reached a Torino Scale rating of 2 and a Palermo Technical Impact Hazard Scale rating of -0.25. With an observation arc of 17 years it is known that closest Earth approach will occur two days earlier on 2 May 2102 at a distance of about 5.5 million km. History was discovered on 7 November 2004, by the NASA-funded LINEAR asteroid survey. The object is estimated by NASA's Near Earth Object Program Office to be 580 meters in diameter with an approximate mass of . Being approximately 580 meters in diameter, if were to impact land, it would create an impact crater about 10 kilometres wide and generate an earthquake of magnitude 7.4. Elevated risk estimate in 2006 From February to May 2006, was listed with a Torino Scale impact risk value of 2, only the second asteroid in risk-monito ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LINEAR
Linearity is the property of a mathematical relationship ('' function'') that can be graphically represented as a straight line. Linearity is closely related to '' proportionality''. Examples in physics include rectilinear motion, the linear relationship of voltage and current in an electrical conductor ( Ohm's law), and the relationship of mass and weight. By contrast, more complicated relationships are ''nonlinear''. Generalized for functions in more than one dimension, linearity means the property of a function of being compatible with addition and scaling, also known as the superposition principle. The word linear comes from Latin ''linearis'', "pertaining to or resembling a line". In mathematics In mathematics, a linear map or linear function ''f''(''x'') is a function that satisfies the two properties: * Additivity: . * Homogeneity of degree 1: for all α. These properties are known as the superposition principle. In this definition, ''x'' is not necessarily ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curve Fitting
Curve fitting is the process of constructing a curve, or mathematical function, that has the best fit to a series of data points, possibly subject to constraints. Curve fitting can involve either interpolation, where an exact fit to the data is required, or smoothing, in which a "smooth" function is constructed that approximately fits the data. A related topic is regression analysis, which focuses more on questions of statistical inference such as how much uncertainty is present in a curve that is fit to data observed with random errors. Fitted curves can be used as an aid for data visualization, to infer values of a function where no data are available, and to summarize the relationships among two or more variables. Extrapolation refers to the use of a fitted curve beyond the range of the observed data, and is subject to a degree of uncertainty since it may reflect the method used to construct the curve as much as it reflects the observed data. For linear-algebraic analy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Exceptional Asteroids
The following is a collection of lists of asteroids of the Solar System that are exceptional in some way, such as their size or orbit. For the purposes of this article, "asteroid" refers to minor planets out to the orbit of Neptune, and includes the dwarf planet 1 Ceres, the Jupiter trojans and the centaurs, but not trans-Neptunian objects (objects in the Kuiper belt, scattered disc or inner Oort cloud). For a complete list of minor planets in numerical order, see List of minor planets. Background Asteroids are given minor planet numbers, but not all minor planets are asteroids. Minor planet numbers are also given to objects of the Kuiper belt, which is similar to the asteroid belt but farther out (around 30–60 AU), whereas asteroids are mostly between 2–3 AU from the Sun and at the orbit of Jupiter 5 AU from the Sun. Also, comets are not typically included under minor planet numbers, and have their own naming conventions. Asteroids are given a u ... [...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 th ... [...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] |
Asteroid Impact Avoidance
Asteroid impact avoidance comprises the methods by which near-Earth objects (NEO) on a potential collision course with Earth could be diverted away, preventing destructive impact events. An impact by a sufficiently large asteroid or other NEOs would cause, depending on its impact location, massive tsunamis or multiple firestorms, and an impact winter caused by the sunlight-blocking effect of large quantities of pulverized rock dust and other debris placed into the stratosphere. A collision 66 million years ago between the Earth and an object approximately wide is thought to have produced the Chicxulub crater and triggered the Cretaceous–Paleogene extinction event that is understood by the scientific community to have caused the extinction of all non-avian dinosaurs. While the chances of a major collision are low in the near term, it is a near- certainty that one will happen eventually unless defensive measures are taken. Astronomical events—such as the Shoemaker-Levy 9 i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
99942 Apophis
99942 Apophis is a near-Earth asteroid and potentially hazardous asteroid with a diameter of that caused a brief period of concern in December 2004 when initial observations indicated a probability up to 2.7% that it would hit Earth on April 13, 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth in 2029. Until 2006, a small probability nevertheless remained that, during its 2029 close encounter with Earth, Apophis would pass through a gravitational keyhole of no more than about in diameter, which would have set up a future impact exactly seven years later on April 13, 2036. This possibility kept it at Level 1 on the Torino impact hazard scale until August 2006, when the probability that Apophis would pass through the keyhole was determined to be very small and Apophis' rating on the Torino scale was lowered to zero. By 2008, the keyhole had been determined to be less than 1 km wide. During the sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3103 Eger
3103 Eger is an Apollo and Mars-crosser asteroid that was discovered in 1982, by Miklós Lovas. It was named after the city of Eger, Hungary. It has an albedo of 0.64, making it a highly reflective asteroid. Description It has made and will continue to make many close approaches to Earth. Its closest approach occurred on 6 August 1996, when the asteroid passed from Earth. The observed YORP value is . 3103 Eger is the only asteroid besides 4 Vesta identified as the parent body for specific meteorites. 4 Vesta is the parent body for Howardite, Eucrite, and Diogenite meteorites, while 3103 Eger is the parent body for Aubrite meteorites. In this characteristic 3103 Eger is related spectroscopically to the 434 Hungaria type asteroids, which are a Hirayama-family of orbital types, and E-type asteroids which form a spectroscopical type. See also * Aubrite * Hungaria family * (144898) 2004 VD17 * 44 Nysa * 2867 Šteins 2867 Šteins (provisional designation ) is an irregula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Absolute Magnitude
Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly , without extinction (or dimming) of its light due to absorption by interstellar matter and cosmic dust. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared among each other on a magnitude scale. As with all astronomical magnitudes, the absolute magnitude can be specified for different wavelength ranges corresponding to specified filter bands or passbands; for stars a commonly quoted absolute magnitude is the absolute visual magnitude, which uses the visual (V) band of the spectrum (in the UBV photometric system). Absolute magnitudes are denoted by a capital M, with a subscript representing the filter band used for mea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albedo
Albedo (; ) is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that reflects all incident radiation. Surface albedo is defined as the ratio of radiosity ''J''e to the irradiance ''E''e (flux per unit area) received by a surface. The proportion reflected is not only determined by properties of the surface itself, but also by the spectral and angular distribution of solar radiation reaching the Earth's surface. These factors vary with atmospheric composition, geographic location, and time (see position of the Sun). While bi-hemispherical reflectance is calculated for a single angle of incidence (i.e., for a given position of the Sun), albedo is the directional integration of reflectance over all solar angles in a given period. The temporal resolution may range from seconds (as obtained from flux measurements) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroid Spectral Types
An asteroid spectral type is assigned to asteroids based on their emission spectrum, color, and sometimes albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not internally differentiated, the surface and internal compositions are presumably similar, while large bodies such as Ceres and Vesta are known to have internal structure. Over the years, there has been a number of surveys that resulted in a set of different taxonomic systems such as the Tholen, SMASS and Bus–DeMeo classifications. Taxonomic systems In 1975, astronomers Clark R. Chapman, David Morrison, and Ben Zellner developed a simple taxonomic system for asteroids based on color, albedo, and spectral shape. The three categories were labelled " C" for dark carbonaceous objects, " S" for stony (silicaceous) objects, and "U" for those that did not fit into either C or S. This basic division of asteroid spectra has since been expanded and clarified.Thomas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sentry (monitoring System)
Sentry is a highly automated impact prediction system operated by the JPL Center for NEO Studies (CNEOS) since 2002. It continually monitors the most up-to-date asteroid catalog for possibilities of future impact with Earth over the next 100+ years. Whenever a potential impact is detected it will be analyzed and the results immediately published by the Center for Near-Earth Object Studies. However, several weeks of optical data are not enough to conclusively identify an impact years in the future. By contrast, eliminating an entry on the risk page is a negative prediction, a prediction of where it will ''not'' be. Scientists warn against worrying about the possibility of impact with an object based on only a few weeks of optical data that show a possible Earth encounter years from now. Sometimes, it cannot even be said for certain what side of the Sun such an object will be at the time of the listed virtual impactor date. For example, even though has a 1-in-500,000 chance of i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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