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Potentially Hazardous Objects
A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make close approaches to the Earth and is large enough to cause significant regional damage in the event of impact. They are defined as having a minimum orbit intersection distance with Earth of less than and an absolute magnitude of 22 or brighter. More than 99% of the known potentially hazardous objects are not an impact threat over the next 100 years. , only 17 potentially hazardous objects are listed on the Sentry Risk Table as objects that are known not to be a threat over the next hundred years are excluded. Over hundreds if not thousands of years, "potentially hazardous" asteroids have the potential for their orbits to evolve to live up to their namesake. Most of these objects are potentially hazardous asteroids (PHAs), and a few are comets. there are 2,304 known PHAs (about 8% of the total near-Earth population), of which 153 are estimated to be large ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toutatis
Toutatis or Teutates is a Celtic god who was worshipped primarily in ancient Gaul and Britain. His name means "god of the tribe", and he has been widely interpreted as a tribal protector.Paul-Marie Duval (1993). ''Les dieux de la Gaule.'' Éditions Payot, Paris. According to Roman writer Lucan, the Gauls offered human sacrifices to him. Name and nature ''Toutatis'' (pronounced in Gaulish)Pierre-Yves Lambert (2003). ''La langue gauloise.'' Éditions Errance, Paris. and its variants ''Toutates'', ''Teutates'', ''Tūtatus'' and ''Toutorīx'', comes from the Gaulish Celtic root ''toutā'', meaning 'tribe' or 'people' (compare Old Irish ''tuath'' and Welsh ''tud''). A literal meaning would thus be "god of the tribe". A similar phrase is found in Irish mythology, which mentions the oath formula ''tongu do dia tongas mo thuath'', roughly "I swear by the god by whom my tribe swears". Bernhard Maier proposes that his name derives from an older *''teuto-tatis'', with the meaning 'fath ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Business Insider
''Insider'', previously named ''Business Insider'' (''BI''), is an American financial and business news website founded in 2007. Since 2015, a majority stake in ''Business Insider''s parent company Insider Inc. has been owned by the German publishing house Axel Springer. It operates several international editions, including one in the United Kingdom. ''Insider'' publishes original reporting and aggregates material from other outlets. , it maintained a liberal policy on the use of anonymous sources. It has also published native advertising and granted sponsors editorial control of its content. The outlet has been nominated for several awards, but is criticized for using factually incorrect clickbait headlines to attract viewership. In 2015, Axel Springer SE acquired 88 percent of the stake in Insider Inc. for $343 million (€306 million), implying a total valuation of $442 million. In February 2021, the brand was renamed simply ''Insider''. History ''Bus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
255P/Levy
255P/Levy, formerly P/2006 T1 and P/2011 Y1, is a periodic comet with an orbital period of 5.25 years. It last came to perihelion (closest approach to the Sun) on 14 January 2012. During the 2006 passage the comet achieved an apparent magnitude of ~9.5. Levy (PK06T010) was believed to have been recovered on 3 June 2011 at magnitude 19.8, but other observatories were unable to confirm a recovery. It was most likely a false positive because of large residuals. Levy was recovered on 17 December 2011 at magnitude 19.8, and given the second designation 2011 Y1. It was then numbered. It came to perihelion on 14 January 2012 at a distance of 1.007 AU from the Sun. The comet passed the Earth on 2012-Jan-26 at a distance of . During the 2012 passage the comet was originally expected to reach an apparent magnitude of 7, but the comet had been in outburst in 2006 and was much dimmer than expected when it was recovered in 2011. MPC estimates after the 2011 recovery estimated that it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
289P/Blanpain
289P/Blanpain, formerly D/1819 W1 (Blanpain) is a short-period comet that was discovered by Jean-Jacques Blanpain on November 28, 1819. Blanpain described the comet as having a "very small and confused nucleus". Another independent discovery was made on December 5 of that year by J. L. Pons. Following this the comet was lost, and was given the designation 'D' (Disappeared or Dead). However, in 2003, the orbital elements of newly discovered asteroid were calculated by Marco Micheli and others to be a probable match for the lost comet. Further observations of the asteroid in 2005 by David Jewitt using the University of Hawaii 2.2 m telescope on Mauna Kea, appeared to reveal a faint coma, which supports the theory that is the lost comet, or a part of it. The comet was officially established as periodic comet 289P in July 2013, after being rediscovered by the Pan-STARRS survey during an outburst event. 289P will be best viewed near and after the 2019-Dec-20 perihelion passage. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
15P/Finlay
Comet Finlay is a periodic comet with an orbital period of 6 years discovered by William Henry Finlay ( Royal Observatory, Cape of Good Hope, South Africa) on September 26, 1886. The next perihelion passage is July 13, 2021 when the comet will have a solar elongation of 54 degrees at approximately apparent magnitude 10. It last came to perihelion on December 27, 2014, at around magnitude 10. Of the numbered periodic comets, the orbit of 15P/Finlay has one of the smallest minimum orbit intersection distances with the orbit of Earth (E-MOID). In October 2060 the comet will pass about 5 million km from Earth. Description When the first orbit calculations were made in 1886, there was a similarity between this orbit and that of Francesco de Vico's lost periodic comet of 1844 ( 54P/de Vico-Swift-NEAT). Lewis Boss ( Dudley Observatory, Schenectady, United States) noted large discrepancies between the orbits and after further observations concluded that de Vico's comet could not b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
55P/Tempel–Tuttle
55P/Tempel–Tuttle (commonly known as Comet Tempel–Tuttle) is a periodic comet with an orbital period of 33 years. It fits the classical definition of a Halley-type comet with a period of between 20 and 200 years. It was independently discovered by Wilhelm Tempel on December 19, 1865, and by Horace Parnell Tuttle on January 6, 1866. It is the parent body of the Leonid meteor shower. In 1699, it was observed by Gottfried Kirch but was not recognized as a periodic comet until the discoveries by Tempel and Tuttle during the 1866 perihelion. In 1933, S. Kanda deduced that the comet of 1366 was Tempel–Tuttle, which was confirmed by Joachim Schubart in 1965. On 26 October 1366, the comet passed from Earth. The orbit of 55P/Tempel–Tuttle intersects that of Earth nearly exactly, hence streams of material ejected from the comet during perihelion passes do not have to spread out over time to encounter Earth. The comet currently has an Earth-MOID of . This coincidence means that s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
109P/Swift-Tuttle
1 (one, unit, unity) is a number representing a single or the only entity. 1 is also a numerical digit and represents a single unit of counting or measurement. For example, a line segment of ''unit length'' is a line segment of length 1. In conventions of sign where zero is considered neither positive nor negative, 1 is the first and smallest positive integer. It is also sometimes considered the first of the infinite sequence of natural numbers, followed by 2, although by other definitions 1 is the second natural number, following 0. The fundamental mathematical property of 1 is to be a multiplicative identity, meaning that any number multiplied by 1 equals the same number. Most if not all properties of 1 can be deduced from this. In advanced mathematics, a multiplicative identity is often denoted 1, even if it is not a number. 1 is by convention not considered a prime number; this was not universally accepted until the mid-20th century. Additionally, 1 is the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minimum Orbit Intersection Distance
Minimum orbit intersection distance (MOID) is a measure used in astronomy to assess potential close approaches and collision risks between astronomical objects. It is defined as the distance between the closest points of the osculating orbits of two bodies. Of greatest interest is the risk of a collision with Earth. Earth MOID is often listed on comet and asteroid databases such as the JPL Small-Body Database. MOID values are also defined with respect to other bodies as well: Jupiter MOID, Venus MOID and so on. An object is classified as a potentially hazardous object (PHO) – that is, posing a possible risk to Earth – if, among other conditions, its Earth MOID is less than 0.05 AU. For more massive bodies than Earth, there is a potentially notable close approach with a larger MOID; for instance, Jupiter MOIDs less than 1 AU are considered noteworthy since Jupiter is the most massive planet.Bruce Koehn,Minimum Orbital Intersection Distance, Lowell Observatory, retrieve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NEOWISE
Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 2011, before being re-activated in 2013 and renamed the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE). WISE discovered thousands of minor planets and numerous star clusters. Its observations also supported the discovery of the first Y-type brown dwarf and Earth trojan asteroid. WISE performed an all-sky astronomical survey with images in 3.4, 4.6, 12 and 22 μm wavelength range bands, over ten months using a diameter infrared telescope in Earth orbit. After its solid hydrogen coolant depleted, a four-month mission extension called NEOWISE was conducted to search for near-Earth objects (NEO) such as comets and asteroids using its remaining capability. The WISE All-Sky (WISEA) data, including processed images, source ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ocean
The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the world ocean is conventionally divided."Ocean." ''Merriam-Webster.com Dictionary'', Merriam-Webster, |
Tsunami
A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explosions (including detonations, landslides, glacier calvings, meteorite impacts and other disturbances) above or below water all have the potential to generate a tsunami. Unlike normal ocean waves, which are generated by wind, or tides, which are in turn generated by the gravitational pull of the Moon and the Sun, a tsunami is generated by the displacement of water from a large event. Tsunami waves do not resemble normal undersea currents or sea waves because their wavelength is far longer. Rather than appearing as a breaking wave, a tsunami may instead initially resemble a rapidly rising tide. For this reason, it is often referred to as a tidal wave, although this usage is not favoured by the scientific community because it might g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Distance (astronomy)
The instantaneous Earth–Moon distance, or distance to the Moon, is the distance from the center of Earth to the center of the Moon. Lunar distance (LD or \Delta_), or Earth–Moon characteristic distance, is a unit of measure in astronomy. More technically, it is the semi-major axis of the geocentric lunar orbit. The lunar distance is on average approximately , or 1.28 light-seconds; this is roughly 30 times Earth's diameter or 9.5 times Earth's circumference. A little less than 400 lunar distances make up an astronomical unit. The semi-major axis has a value of . The time-averaged distance between the centers of Earth and the Moon is . The actual distance varies over the course of the orbit of the Moon, from at the perigee to at apogee, resulting in a differential range of . Lunar distance is commonly used to express the distance to near-Earth object encounters. Lunar semi-major axis is an important astronomical datum; the few millimeter precision of the range measureme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
