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Asteroid 1950 DA
, provisional designation ', is a risk–listed asteroid, classified as a near-Earth object and potentially hazardous asteroid of the Apollo group, approximately in diameter. It once had the highest known probability of impacting Earth. In 2002, it had the highest Palermo rating with a value of 0.17 for a possible collision in 2880. Since that time, the estimated risk has been updated several times. In December 2015, the odds of an Earth impact were revised to 1 in 8,300 (0.012%) with a Palermo rating of −1.42. As of 2022, It is listed on the Sentry Risk Table with the second highest cumulative Palermo rating of −2.05 (impact risk of 1-in-34,000). is not assigned a Torino scale rating, because the 2880 date is over 100 years in the future. Discovery and nomenclature ' was first discovered on 23 February 1950 by Carl A. Wirtanen at Lick Observatory. It was observed for seventeen days and then lost because this short observation arc resulted in large uncertainties in W ... [...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 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 and providing a refined value for the astronomical unit. Radar images provide information about the shapes and surface properties of solid bodies, which ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Near-Earth Object
A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). If a NEO's orbit crosses the Earth's orbit, and the object is larger than across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but a small fraction are comets. There are over 30,503 known near-Earth asteroids (NEAs) and over a hundred known short-period near-Earth comets (NECs). A number of solar-orbiting meteoroids were large enough to be tracked in space before striking the Earth. It is now widely accepted that collisions in the past have had a significant role in shaping the geological and biological history of the Earth. Asteroids as small as in diameter can cause significant damage to the local environment and human populations. Larger asteroids penetrate the atmosphere to the surf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in front of oxygen (32.1% and 30.1%, respectively), forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. In its metallic state, iron is rare in the Earth's crust, limited mainly to deposition by meteorites. Iron ores, by contrast, are among the most abundant in the Earth's crust, although extracting usable metal from them requires kilns or furnaces capable of reaching or higher, about higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BCE and the use of iron tools and weapons began to displace copper alloys, in some regions, only around 1200 BCE. That event is considered the transition from the Bronze Age to the Iron A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to react with air under standard conditions because a passivation layer of nickel oxide forms on the surface that prevents further corrosion. Even so, pure native nickel is found in Earth's crust only in tiny amounts, usually in ultramafic rocks, and in the interiors of larger nickel–iron meteorites that were not exposed to oxygen when outside Earth's atmosphere. Meteoric nickel is found in combination with iron, a reflection of the origin of those elements as major end products of supernova nucleosynthesis. An iron–nickel mixture is thought to compose Earth's outer and inner cores. Use of nickel (as natural meteoric nickel–iron alloy) has been traced as far back as 3500 BCE. Nickel was first isolated and classified as an e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albedo
Albedo (; ) is the measure of the diffuse reflection of sunlight, 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 (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 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 ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petr Pravec
Petr Pravec (born September 17, 1967) is a Czech astronomer and a discoverer of minor planets, born in Třinec, Czech Republic. Pravec is a prolific discoverer of binary asteroids, expert in photometric observations and rotational lightcurves at Ondřejov Observatory. He is credited by the Minor Planet Center with the discovery and co-discovery of 350 numbered minor planets, and is leading the effort of a large consortium of stations called "BinAst" to look for multiplicity in the near-Earth objects and inner main-belt populations. He is a member of the ''Academy of Sciences of the Czech Republic''. The main-belt asteroid 4790 Petrpravec, discovered by Eleanor Helin Eleanor Francis "Glo" Helin (née Francis, 19 November 1932 – 25 January 2009) was an American astronomer. She was principal investigator of the Near-Earth Asteroid Tracking (NEAT) program of NASA's Jet Propulsion Laboratory. (Some sources gi ... in 1988, is named after him. The official naming citation was ... [...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] |
Goldstone Observatory
The Goldstone Deep Space Communications Complex (GDSCC), commonly called the Goldstone Observatory, is a satellite ground station located in Fort Irwin in the U.S. state of California. Operated by NASA's Jet Propulsion Laboratory (JPL), its main purpose is to track and communicate with interplanetary space missions. It is named after Goldstone, California, a nearby gold-mining ghost town. The station is one of three satellite communication stations in the NASA Space Communications and Navigation (SCaN) program’s Deep Space Network (DSN), whose mission is to provide the vital two-way communications link that tracks and controls interplanetary spacecraft and receives the images and scientific information they collect. The others are the Madrid Deep Space Communications Complex in Spain and the Canberra Deep Space Communication Complex in Australia. These three stations are located at separations of approximately 120° longitude so that as the Earth rotates a spacecraft wil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LONEOS
Lowell Observatory Near-Earth-Object Search (LONEOS) was a project designed to discover asteroids and comets that orbit near the Earth. The project, funded by NASA, was directed by astronomer Ted Bowell of Lowell Observatory in Flagstaff, Arizona. The LONEOS project began in 1993 and ran until the end of February 2008. Hardware LONEOS, in its final configuration, used a 0.6-meter f/1.8 Schmidt telescope, acquired from Ohio Wesleyan University in 1990, and a Lowell-built 16 megapixel CCD detector. This combination of instruments provided a field of view of 2.88 by 2.88 degrees (8.3 square degrees). It had a maximum nightly scan area of about 1,000 square degrees (covered four times). The instrument could cover the entire accessible dark sky in about a month. The CCD has detected asteroids as faint as visual magnitude 19.8 but its typical limiting visual magnitude was 19.3. The instrument is located at Lowell Observatory's dark sky site, Anderson Mesa Station, near Flagstaff, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lost Asteroid
A minor planet is "lost" when today's observers cannot find it, because its location is too uncertain to target observations. This happens if the orbital elements of a minor planet are not known accurately enough, typically because the observation arc for the object is too short, or too few observations were made before the object became unobservable (e.g. too faint due to increasing distance, or too close to the Sun to view at night). By some definitions thousands, if not tens of thousands, of mostly small observed minor planets are lost. Some lost minor planets discovered in decades past cannot be found because the available observational data is insufficient for reliable orbit determination. With limited information astronomers cannot know where to look for the object at future dates. Lost objects are sometimes recovered when serendipitously re-observed by a later astronomical survey. If the orbital elements of the newly found object are sufficiently close to those of the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torino Scale
The Torino scale is a method for categorizing the impact hazard associated with near-Earth objects (NEOs) such as asteroids and comets. It is intended as a communication tool for astronomers and the public to assess the seriousness of collision predictions, by combining probability statistics and known kinetic damage potentials into a single threat value. The Palermo Technical Impact Hazard Scale is a similar, but more complex scale. Near-Earth objects with a Torino scale of 1 pop up every couple of months or so and may last a few weeks until they have a longer observation arc. Overview The Torino Scale uses an integer scale from 0 to 10. A 0 indicates an object has a negligibly small chance of collision with the Earth, compared with the usual "background noise" of collision events, or is too small to penetrate Earth's atmosphere intact. A 10 indicates that a collision is certain, and the impacting object is large enough to precipitate a global disaster. An object is assigned a 0 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palermo Technical Impact Hazard Scale
The Palermo Technical Impact Hazard Scale is a logarithmic scale used by astronomers to rate the potential hazard of impact of a near-Earth object (NEO). It combines two types of data—probability of impact and estimated kinetic yield—into a single "hazard" value. A rating of 0 means the hazard is equivalent to the background hazard (defined as the average risk posed by objects of the same size or larger over the years until the date of the potential impact). A rating of +2 would indicate the hazard is 100 times as great as a random background event. Scale values less than −2 reflect events for which there are no likely consequences, while Palermo Scale values between −2 and 0 indicate situations that merit careful monitoring. A similar but less complex scale is the Torino Scale, which is used for simpler descriptions in the non-scientific media. As of December 2022, one asteroid has a cumulative Palermo Scale value above −2: 101955 Bennu (−1.41). Five have cumu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
