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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] |
2020VV Risk Corridor
VV, V V, or v. v. may refer to: Arts and entertainment * Vopli Vidopliassova, a Ukrainian rock band * V/V, a secondary chord in music * V.V., a list of Code Geass characters#V.V., character in ''Code Geass'' * Ville Valo, Finnish vocalist for gothic rock band HIM also known as VV Organisations * Aerosvit Airlines (former IATA code: VV), a former Ukrainian airline * Internal Troops of Russia (), a former paramilitary force * Public Affairs (political party) (), a political party * Vicarious Visions, a video game company * Viva Air Perú (former IATA code: VV), a former Ukrainian airline Science and technology * v/v (volume by volume), the volume fraction * VV Cephei, a star system * Vorontsov-Vel'yaminov Interacting Galaxies, a catalogue of galaxies * V//V, the Intel Viiv platform initiative People * Alison Mosshart (stage name VV; born 1978), American singer with The Kills * Vasily Vorontsov (pseudonym VV; 1847–1918), Russian economist and sociologist * Ville Valo (VV; born 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Belt
The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids or minor planets. The identified objects are of many sizes, but much smaller than planets, and, on average, are about one million kilometers (or six hundred thousand miles) apart. This asteroid belt is also called the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System. The asteroid belt is the smallest and innermost circumstellar disc in the Solar System. Classes of small Solar System bodies in other regions are the near-Earth objects, the centaurs, the Kuiper belt objects, the scattered disc objects, the sednoids, and the Oort cloud objects. About 60% of the main belt mass is contained in the four largest asteroids: Ceres, Vesta, Pallas, and Hygiea. The total mass of the asteroid be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jet Propulsion Laboratory Development Ephemeris
Jet Propulsion Laboratory Development Ephemeris (abbreviated JPL DE(number), or simply DE(number)) designates one of a series of mathematical models of the Solar System produced at the Jet Propulsion Laboratory in Pasadena, California, for use in spacecraft navigation and astronomy. The models consist of numeric representations of positions, velocities and accelerations of major Solar System bodies, tabulated at equally spaced intervals of time, covering a specified span of years. Barycentric rectangular coordinates of the Sun, eight major planets and Pluto, and geocentric coordinates of the Moon are tabulated. History There have been many versions of the JPL DE, from the 1960s through the present, in support of both robotic and crewed spacecraft missions. Available documentation is limited, but we know DE69 was announced in 1969 to be the third release of the JPL Ephemeris Tapes, and was a special purpose, short-duration ephemeris. The then-current JPL Export Ephemeris was DE1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ephemeris
In astronomy and celestial navigation, an ephemeris (; ; , ) is a book with tables that gives the trajectory of naturally occurring astronomical objects and artificial satellites in the sky, i.e., the position (and possibly velocity) over time. Historically, positions were given as printed tables of values, given at regular intervals of date and time. The calculation of these tables was one of the first applications of mechanical computers. Modern ephemerides are often provided in electronic form. However, printed ephemerides are still produced, as they are useful when computational devices are not available. The astronomical position calculated from an ephemeris is often given in the spherical polar coordinate system of right ascension and declination, together with the distance from the origin if applicable. Some of the astronomical phenomena of interest to astronomers are eclipses, apparent retrograde motion/planetary stations, planetary es, sidereal time, positions for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albedo
Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is 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 (radiometry), 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 directional-hemispherical reflectance factor 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infrared Astronomy
Infrared astronomy is a sub-discipline of astronomy which specializes in the astronomical observation, observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in between Visible light, visible radiation, which ranges from 380 to 750 nanometers, and terahertz radiation, submillimeter waves. Infrared astronomy began in the 1830s, a few decades after the discovery of infrared light by William Herschel in 1800. Early progress was limited, and it was not until the early 20th century that conclusive detections of astronomical objects other than the Sun and Moon were made in infrared light. After a number of discoveries were made in the 1950s and 1960s in radio astronomy, astronomers realized the information available outside the visible wavelength range, and modern infrared astronomy was established. Infrared and optical astronomy are often practiced using the same telescopes, as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar Astronomy
Radar astronomy is a technique of observing nearby astronomical objects by reflecting radio waves or microwaves off target objects and analyzing their reflections. Radar astronomy differs from ''radio astronomy'' in that the latter is a passive observation (i.e., receiving only) and the former an active one (transmitting and receiving). Radar systems have been conducted for six decades applied to a wide range of Solar System studies. The radar transmission may either be pulsed or continuous. The strength of the radar return signal is radar#Radar range equation, proportional to the inverse fourth-power of the distance. Upgraded facilities, increased transceiver power, and improved apparatus have increased observational opportunities. Radar techniques provide information unavailable by other means, such as testing general relativity by observing Mercury (planet), Mercury and providing a refined value for the astronomical unit. Radar imaging, Radar images provide information about th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
367943 Duende
367943 Duende (Provisional designation in astronomy, provisional designation ) is a micro-asteroid and a near-Earth object of the Aten asteroid, Aten and Atira asteroid, Atira group, approximately in diameter. It was discovered by astronomers of the Astronomical Observatory of Mallorca at its robotic La Sagra Observatory in 2012, and named for the Duende (mythology), duende, a goblin-like creature from Iberian mythology and folklore. ''Duende'' is likely an uncommon L-type asteroid and significantly elongated. For an asteroid of its size, it has a relatively long rotation period of 9.485 hours. On 15 February 2013, ''Duende'' passed at a List of record-setting asteroid close approaches to Earth, record distance of or 4.3 Earth radius, Earth radii from Earth's surface. Due to its close passage, its orbit was Perturbation (astronomy), perturbed significantly enough that it changed from an Apollo asteroid to an Aten asteroid. ''Duende'' passage also Chelyabinsk meteor#Coincidental ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
(410777) 2009 FD
(410777) 2009 FD is a carbonaceous sub-kilometer asteroid and binary system, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, discovered on 24 February 2009 by astronomers of the Spacewatch program at Kitt Peak National Observatory near Tucson, Arizona, in the United States. Until 2019, the asteroid's modelled orbit placed it at risk of a possible future collision with Earth in 2185. With a Palermo scale rating of -0.44, it had the fifth highest impact threat of all known asteroids based on its estimated diameter, kinetic yield, impact probability, and time interval. Observations in 2019 extended the observation arc by four years and detected a favourable Yarkovsky effect, which ruled out impact in 2185. Using observations from 16 November 2020, the asteroid was removed from the Sentry risk table on 19 November 2020. Discovery was initially announced as discovered on 16 March 2009 by La Sagra Sky Survey. Because there were previous ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
99942 Apophis
99942 Apophis ( provisional designation ) is a near-Earth asteroid and a potentially hazardous object, 450 metres (1,480 ft) by 170 metres (560 ft) in size, that caused a brief period of concern in December 2004 when initial observations indicated a probability of 0.027 (2.7%) that it would hit Earth on Friday, April 13, 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth in 2029. A small possibility nevertheless remained that, during its 2029 close encounter with Earth, Apophis would pass through a gravitational keyhole estimated to be 800 metres in diameter, which would have set up a future impact exactly seven years later on Easter Sunday, April 13, 2036. This possibility kept it at Level 1 on the 0 to 10 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's rating on the Torino scale was lowe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
