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JPL SBDB
The JPL Small-Body Database (SBDB) is an astronomy database about small Solar System bodies. It is maintained by Jet Propulsion Laboratory (JPL) and NASA and provides data for all known asteroids and several comets, including orbital parameters and diagrams, physical diagrams, close approach details, radar astrometry, discovery circumstances, alternate designations and lists of publications related to the small body. The database is updated daily when new observations are available. In April 2021 the JPL Small-Body Database started using planetary ephemeris ( DE441) and small-body perturber SB441-N16. Most objects such as asteroids get a two-body solution (Sun+object) recomputed twice a year. Comets generally have their two-body orbits computed at a time near the perihelion passage (closest approach to the Sun) as to have the two-body orbit more reasonably accurate for both before and after perihelion. For most asteroids, the epoch used to define an orbit is updated twice a year. Or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomy
Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest include planets, natural satellite, moons, stars, nebulae, galaxy, galaxies, meteoroids, asteroids, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond atmosphere of Earth, Earth's atmosphere. Cosmology is a branch of astronomy that studies the universe as a whole. Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Egyptian astronomy, Egyptians, Babylonian astronomy, Babylonians, Greek astronomy, Greeks, Indian astronomy, Indians, Chinese astronomy, Chinese, Maya civilization, M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JavaScript
JavaScript (), often abbreviated as JS, is a programming language and core technology of the World Wide Web, alongside HTML and CSS. Ninety-nine percent of websites use JavaScript on the client side for webpage behavior. Web browsers have a dedicated JavaScript engine that executes the client code. These engines are also utilized in some servers and a variety of apps. The most popular runtime system for non-browser usage is Node.js. JavaScript is a high-level, often just-in-time–compiled language that conforms to the ECMAScript standard. It has dynamic typing, prototype-based object-orientation, and first-class functions. It is multi-paradigm, supporting event-driven, functional, and imperative programming styles. It has application programming interfaces (APIs) for working with text, dates, regular expressions, standard data structures, and the Document Object Model (DOM). The ECMAScript standard does not include any input/output (I/O), such as netwo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observational Astronomy
Observational astronomy is a division of astronomy that is concerned with recording data about the observable universe, in contrast with theoretical astronomy, which is mainly concerned with calculating the measurable implications of physical models. It is the practice and study of observing celestial objects with the use of telescopes and other astronomical instruments. As a science, the study of astronomy is somewhat hindered in that direct experiments with the properties of the distant universe are not possible. However, this is partly compensated by the fact that astronomers have a vast number of visible examples of stellar phenomena that can be examined. This allows for observational data to be plotted on graphs, and general trends recorded. Nearby examples of specific phenomena, such as variable stars, can then be used to infer the behavior of more distant representatives. Those distant yardsticks can then be employed to measure other phenomena in that neighborhood, inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sentry (monitoring System)
Sentry is an automated Asteroid impact prediction, impact prediction system started in 2002 and operated by the Center for Near-Earth Object Studies, Center for Near Earth Object Studies (CNEOS) at NASA's Jet Propulsion Laboratory. 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 CNEOS. However, alerts do not imply certainty about future impacts, as the small amounts of optical data that can trigger an alert are not enough to conclusively identify an impact years in the future. In 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 sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NEODyS
NEODyS (Near Earth Objects Dynamic Site) is an Italian service that provides information on near-Earth objects with a Web-based interface. It is based on a continually and (almost) automatically maintained database of near earth asteroid orbits. This site provides a number of services to the NEO community. The main service is an impact monitoring system (CLOMON2) of all near-Earth asteroids covering a period until the year 2100. Services * Risk Page: One of the most important services is the production of a Risk Page where 1128 NEOs with probabilities of hitting the Earth greater of 10−11 from now until 2100 are shown in a Risk list. In the table of the Risk list the NEOs are divided into "Special", as it is the case of 101955 Bennu; "Observable", objects which are presently observable and which critically need a follow-up in order to improve their orbit; "Possible recovery", objects which are not visible at present, but which are possible to recover in the near future; "Lost", ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Numerical Integration
In analysis, numerical integration comprises a broad family of algorithms for calculating the numerical value of a definite integral. The term numerical quadrature (often abbreviated to quadrature) is more or less a synonym for "numerical integration", especially as applied to one-dimensional integrals. Some authors refer to numerical integration over more than one dimension as cubature; others take "quadrature" to include higher-dimensional integration. The basic problem in numerical integration is to compute an approximate solution to a definite integral :\int_a^b f(x) \, dx to a given degree of accuracy. If is a smooth function integrated over a small number of dimensions, and the domain of integration is bounded, there are many methods for approximating the integral to the desired precision. Numerical integration has roots in the geometrical problem of finding a square with the same area as a given plane figure ('' quadrature'' or ''squaring''), as in the quadrature of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-body Problem
In physics, the -body problem is the problem of predicting the individual motions of a group of astronomical object, celestial objects interacting with each other gravitationally.Leimanis and Minorsky: Our interest is with Leimanis, who first discusses some history about the -body problem, especially Ms. Kovalevskaya's 1868–1888 twenty-year complex-variables approach, failure; Section 1: "The Dynamics of Rigid Bodies and Mathematical Exterior Ballistics" (Chapter 1, "The motion of a rigid body about a fixed point (Euler and Poisson equations)"; Chapter 2, "Mathematical Exterior Ballistics"), good precursor background to the -body problem; Section 2: "Celestial Mechanics" (Chapter 1, "The Uniformization of the Three-body Problem (Restricted Three-body Problem)"; Chapter 2, "Capture in the Three-Body Problem"; Chapter 3, "Generalized -body Problem"). Solving this problem has been motivated by the desire to understand the motions of the Sun, Moon, planets, and visible stars. In th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JPL Horizons On-Line Ephemeris System
JPL Horizons On-Line Ephemeris System provides access to key Solar System data and flexible production of highly accurate ephemerides for Solar System objects. Osculating elements at a given epoch (such as produced by the JPL Small-Body Database) are always an approximation to an object's orbit (i.e. an unperturbed conic orbit or a " two-body" orbit). The real orbit (or the best approximation to such) considers perturbations by all planets, a few of the larger asteroids, a few other usually small physical forces, and requires numerical integration. Jet Propulsion Laboratory (JPL) ephemerides do not use things such as periods, eccentricities, etc. Instead, JPL integrates the equations of motion in Cartesian coordinates (x,y,z), and adjusts the initial conditions in order to fit modern, highly accurate measurements of planetary positions. Since August 2013, Horizons has been using ephemeris DE431. During the week of 12 April 2021, the Horizons ephemeris system was updated t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apsis
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides pertaining to orbits around different bodies have distinct names to differentiate themselves from other apsides. Apsides pertaining to geocentric orbits, orbits around the Earth, are at the farthest point called the ''apogee'', and at the nearest point the ''perigee'', like with orbits of satellites and the Moon around Earth. Apsides pertaining to orbits around the Sun are named ''aphelion'' for the farthest and ''perihelion'' for the nearest point in a heliocentric orbit. Earth's two apsides are the farthest point, ''aphelion'', and the nearest point, ''perihelion'', of its orbit around the host Sun. The terms ''aphelion'' and ''perihelion'' apply in the same way to the orbits of Jupiter and the other planets, the comets, and the asteroids of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-body Problem
In classical mechanics, the two-body problem is to calculate and predict the motion of two massive bodies that are orbiting each other in space. The problem assumes that the two bodies are point particles that interact only with one another; the only force affecting each object arises from the other one, and all other objects are ignored. The most prominent example of the classical two-body problem is the gravitational case (see also Kepler problem), arising in astronomy for predicting the orbits (or escapes from orbit) of objects such as satellites, planets, and stars. A two-point-particle model of such a system nearly always describes its behavior well enough to provide useful insights and predictions. A simpler "one body" model, the " central-force problem", treats one object as the immobile source of a force acting on the other. One then seeks to predict the motion of the single remaining mobile object. Such an approximation can give useful results when one object is much ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WebGL
WebGL (short for Web Graphics Library) is a JavaScript Application programming interface, API for rendering interactive 2D and 3D graphics within any compatible web browser without the use of plug-in (computing), plug-ins. WebGL is fully integrated with other Web API, web standards, allowing graphics processing unit, GPU-accelerated usage of physics, image processing, and effects in the HTML Canvas element, canvas. WebGL elements can be mixed with other HTML elements and composited with other parts of the page or page background. WebGL programs consist of control code written in JavaScript, and shader code written in OpenGL Shading Language, OpenGL ES Shading Language (GLSL ES, sometimes referred to as ESSL), a language similar to C (programming language), C or C++. WebGL code is executed on a computer's GPU. WebGL is designed and maintained by the Non-profit organization, non-profit Khronos Group. On February 9, 2022, Khronos Group announced WebGL 2.0 support from all major bro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Three
3 (three) is a number, numeral and digit. It is the natural number following 2 and preceding 4, and is the smallest odd prime number and the only prime preceding a square number. It has religious and cultural significance in many societies. Evolution of the Arabic digit The use of three lines to denote the number 3 occurred in many writing systems, including some (like Roman and Chinese numerals) that are still in use. That was also the original representation of 3 in the Brahmic (Indian) numerical notation, its earliest forms aligned vertically. However, during the Gupta Empire the sign was modified by the addition of a curve on each line. The Nāgarī script rotated the lines clockwise, so they appeared horizontally, and ended each line with a short downward stroke on the right. In cursive script, the three strokes were eventually connected to form a glyph resembling a with an additional stroke at the bottom: ३. The Indian digits spread to the Caliphate in the 9th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
