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4769 Castalia
4769 Castalia (; ''Minor planet provisional designation, prov. designation:'' ) is a near-Earth object and potentially hazardous asteroid of the Apollo asteroid, Apollo group, approximately in diameter and was the first asteroid to be modeled by radar imaging. It was discovered on 9 August 1989, by American astronomer Eleanor Helin (Caltech) on photographic plates taken at Palomar Observatory in California. It is named after Castalia, a nymph in Greek mythology. It is also a Mars-crosser asteroid, Mars- and Venus-crosser asteroid. General information On 25 August 1989 Castalia passed (within eleven Lunar distance (astronomy), lunar distances) of Earth, allowing it to be observed with Radar astronomy, radar from the Arecibo Observatory by Scott Hudson (electrical engineer), Scott Hudson (Washington State University) and Steven J. Ostro (Jet Propulsion Laboratory, JPL). The data allowed Hudson et al. to produce a three-dimensional Mathematical model, model of the object. During ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arecibo Observatory
The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US National Science Foundation (NSF). The observatory's main instrument was the Arecibo Telescope, a spherical reflector dish built into a natural sinkhole, with a cable-mount steerable receiver and several radar transmitters for emitting signals mounted above the dish. Completed in 1963, it was the world's largest single-aperture telescope for 53 years, surpassed in July 2016 by the Five-hundred-meter Aperture Spherical Telescope (FAST) in China. On August 10 and November 6, 2020, two of the receiver's support cables broke and the NSF announced that it would decommission the telescope. The telescope collapsed on December 1, 2020. In 2022, the NSF announced the telescope will not be rebuilt, with an educational facility to be established on the site. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potentially Hazardous Asteroid
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 which is large enough to cause significant regional damage in the event of impact. They are conventionally defined as having a minimum orbit intersection distance with Earth of less than and an absolute magnitude of 22 or brighter, the latter of which roughly corresponds to a size larger than 140 meters. More than 99% of the known potentially hazardous objects are no impact threat over the next 100 years. , just 21 of the known potentially hazardous objects listed on the Sentry Risk Table could not be excluded as potential threats over the next hundred years. Over hundreds if not thousands of years though, the orbits of some "potentially hazardous" asteroids can 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jet Propulsion Laboratory
The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center (FFRDC) in La Cañada Flintridge, California, Crescenta Valley, United States. Founded in 1936 by California Institute of Technology (Caltech) researchers, the laboratory is now owned and sponsored by NASA and administered and managed by Caltech. The primary function of the laboratory is the construction and operation of planetary robotic spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating the NASA Deep Space Network (DSN). Among the major active projects at the laboratory, some are the Mars 2020 mission, which includes the ''Perseverance (rover), Perseverance'' rover; the Mars Science Laboratory mission, including the ''Curiosity (rover), Curiosity'' rover; the ''Mars Reconnaissance Orbiter''; the ''Juno (spacecraft), Juno'' spacecraft orbiting Jupiter; the ''Soil Moisture Active P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steven J
Stephen or Steven is an English first name. It is particularly significant to Christians, as it belonged to Saint Stephen ( ), an early disciple and deacon who, according to the Book of Acts, was stoned to death; he is widely regarded as the first martyr (or " protomartyr") of the Christian Church. The name, in both the forms Stephen and Steven, is often shortened to Steve or Stevie. In English, the female version of the name is Stephanie. Many surnames are derived from the first name, including Stephens, Stevens, Stephenson, and Stevenson, all of which mean "Stephen's (son)". In modern times the name has sometimes been given with intentionally non-standard spelling, such as Stevan or Stevon. A common variant of the name used in English is Stephan ( ); related names that have found some currency or significance in English include Stefan (pronounced or in English), Esteban (often pronounced ), and the Shakespearean Stephano ( ). Origins The name "Stephen" (and it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Washington State University
Washington State University (WSU, or colloquially Wazzu) is a Public university, public Land-grant university, land-grant research university in Pullman, Washington, United States. Founded in 1890, WSU is also one of the oldest Land-grant university, land-grant universities in the Western United States, American West. With an undergraduate enrollment of 24,278 and a total enrollment of 28,581, it is the second largest institution of higher education in Washington state behind the University of Washington. It is Carnegie Classification of Institutions of Higher Education, classified among "R1: Doctoral Universities – Very high research activity". The WSU Pullman campus stands on a hill and is characterized by open spaces and a red brick and basalt material palette—materials originally found on site. The university sits within the rolling topography of the Palouse in rural eastern Washington and remains closely connected to the town and the region. The university also operat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scott Hudson (electrical Engineer)
Raymond Scott Hudson (born 1959) is a professor of electrical engineering and computer science at Washington State University. Hudson was educated at Caltech, where he received his bachelor's degree in engineering and applied science in 1985, his master's degree in electrical engineering in 1986, and his PhD in electrical engineering in 1990. His research interests include radar imaging, optical signal processing, and radar astronomy. From August 19 to 22 of 1989, Hudson and Steven Ostro observed 4769 Castalia from the Arecibo Observatory, producing the first direct image of an asteroid. The main-belt asteroid 5723 Hudson, discovered by Edward Bowell at Lowell Observatory Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark ... in 1986, was named in his honour. The official naming cita ... [...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] |
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. In contrast, the 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 orbit of the Moon, lunar orbit. The average lunar distance is approximately , or 1.3 light-seconds. It is roughly 30 times Earth radius, Earth's diameter and a non-stop plane flight traveling that distance would take more than two weeks. Around 389 lunar distances make up an astronomical unit (roughly the distance from Earth to the Sun). Lunar distance is commonly used to express the distance to near-Earth object encounters. Lunar semi-major axis is an important astronomical datum. It has implications for testing gravitational theories such as general relativity and for refining other astronomical values, such as the Earth mass, mass, Earth radius, radius, and Ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Mythology
Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories concern the ancient Greek religion's view of the Cosmogony, origin and Cosmology#Metaphysical cosmology, nature of the world; the lives and activities of List of Greek deities, deities, Greek hero cult, heroes, and List of Greek mythological creatures, mythological creatures; and the origins and significance of the ancient Greeks' cult (religious practice), cult and ritual practices. Modern scholars study the myths to shed light on the religious and political institutions of ancient Greece, and to better understand the nature of mythmaking itself. The Greek myths were initially propagated in an oral tradition, oral-poetic tradition most likely by Minoan civilization, Minoan and Mycenaean Greece, Mycenaean singers starting in the 18th century&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nymph
A nymph (; ; sometimes spelled nymphe) is a minor female nature deity in ancient Greek folklore. Distinct from other Greek goddesses, nymphs are generally regarded as personifications of nature; they are typically tied to a specific place, landform, or tree, and are usually depicted as Virginity, maidens. Because of their association with springs, they were often seen as having healing properties; other divine powers of the nymphs included divination and shapeshifting. In spite of their divine nature, they were not immortality, immortal. Nymphs are divided into various Nymph#List, broad subgroups based on their habitat, such as the Meliae (ash tree nymphs), the Dryads (oak tree nymphs), the Alseids (Grove (nature), grove nymphs), the Naiads (Spring (hydrology), spring nymphs), the Nereids (sea nymphs), the Oceanids (ocean nymphs), and the Oreads (mountain nymphs). Other nymphs included the Hesperides (evening nymphs), the Hyades (mythology), Hyades (rain nymphs), and the Pleiade ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caltech
The California Institute of Technology (branded as Caltech) is a private university, private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small group of Institute of Technology (United States), institutes of technology in the United States that are devoted to the instruction of pure and applied sciences. The institution was founded as a preparatory and vocational school by Amos G. Throop in 1891 and began attracting influential scientists such as George Ellery Hale, Arthur Amos Noyes, and Robert Andrews Millikan in the early 20th century. The vocational and preparatory schools were disbanded and spun off in 1910, and the college assumed its present name in 1920. In 1934, Caltech was elected to the Association of American Universities, and the antecedents of NASA's Jet Propulsion Laboratory, which Caltech continues to manage and operate, were established between 1936 and 1943 under ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 give her name as Eleanor Kay Helin.) Helin was a prolific discoverer of minor planets ''(see #List of discovered minor planets, list)'' and several comets, including periodic comets 111P/Helin–Roman–Crockett, 117P/Helin–Roman–Alu and 132P/Helin–Roman–Alu. She is credited as the discoverer of the object now known as both asteroid 4015 Wilson–Harrington and comet 107P/Wilson–Harrington. Although Wilson and Robert George Harrington, Harrington preceded her by some decades, their observations did not establish an orbit for the object, while her rediscovery did. Helin discovered or co-discovered 903 asteroids and several comets. Biography Helin was born an only child to Fred and Kay Francis. At the age of five, she became ill w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
