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645 Agrippina
645 Agrippina, provisional designation 1907 AG, is a stony asteroid from the outer region of the asteroid belt, roughly 30 kilometers in diameter. It was discovered by American astronomer reverend Joel Metcalf at Taunton, Massachusetts, USA, on 13 September 1907. The S-type asteroid orbits the Sun at a distance of 2.7–3.7 AU once every 5 years and 9 months (2,103 days). Its orbit shows an eccentricity of 0.15 and is tilted by 7 degrees to the plane of the ecliptic. A photometric light-curve analysis from the 1980s and a provisional observation in 2004 rendered a rotation period of 32.6 and 34.4 hours, respectively. According to the surveys carried out by the Infrared Astronomical Satellite, IRAS, the Japanese Akari satellite, and the U.S. Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid has a dissimilar albedo in the range of 0.14 to 0.23, which leads to a varying estimate for its diameter from 28 to 36 kilometers. The ''Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joel Hastings Metcalf
Joel Hastings Metcalf (January 4, 1866 – February 23, 1925) was an American astronomer, humanitarian and Minister (Christianity), minister. Reverend Metcalf graduated from Harvard Divinity School in 1892. He served as a Unitarianism, Unitarian minister in Burlington, Vermont and in Taunton, Massachusetts, Winchester, Massachusetts and Portland, Maine. He discovered or co-discovered several comets, including 23P/Brorsen-Metcalf and 97P/Metcalf-Brewington, and also 41 asteroids during 1905–1914, as credited by the Minor Planet Center. Two of his discoveries, the main-belt asteroids 726 Joëlla and 792 Metcalfia, were named in his honor. Bibliography See also References External links Joel Hastings Metcalf – Minister, Humanitarian, AstronomerMetcalf, Joel Hastings (1866-1925) {{DEFAULTSORT:Metcalf, Joel Hastings 1866 births 1925 deaths American astronomers Discoverers of asteroids Discoverers of comets Harvard Divinity School alumni People from Bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Eccentricity
In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit (or capture orbit), and greater than 1 is a hyperbola. The term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the Galaxy. Definition In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit. The eccentricity of this Kepler orbit is a non-negative number that defines its shape. The eccentricity may take the following values: * circular orbit: ''e'' = 0 * elliptic orbit: 0 < ''e'' < 1 * [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nero
Nero Claudius Caesar Augustus Germanicus ( ; born Lucius Domitius Ahenobarbus; 15 December AD 37 – 9 June AD 68), was the fifth Roman emperor and final emperor of the Julio-Claudian dynasty, reigning from AD 54 until his death in AD 68. He was adopted by the Roman emperor Claudius at the age of 13 and succeeded him on the throne. Nero was popular with the members of his Praetorian Guard and lower-class commoners in Rome and its provinces, but he was deeply resented by the Roman aristocracy. Most contemporary sources describe him as tyrannical, self-indulgent, and debauched. After being declared a public enemy by the Roman Senate, he committed suicide at age 30. Nero was born at Antium in AD 37, the son of Gnaeus Domitius Ahenobarbus and Agrippina the Younger, a great-granddaughter of the emperor Augustus. When Nero was two years old, his father died. His mother married the emperor Claudius, who eventually adopted Nero as his heir; when Cla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caligula
Gaius Julius Caesar Augustus Germanicus (31 August 12 – 24 January 41), better known by his nickname Caligula (), was the third Roman emperor, ruling from 37 until his assassination in 41. He was the son of the popular Roman general Germanicus and Augustus' granddaughter Agrippina the Elder. Caligula was born into the first ruling family of the Roman Empire, conventionally known as the Julio-Claudian dynasty. Although Gaius was named after Julius Caesar, Gaius Julius Caesar, he acquired the nickname "Caligula" ("little ''caligae, caliga''," a type of military boot) from his father's soldiers during their campaign in Germania. When Germanicus died at Antioch in 19, Agrippina returned with her six children to Rome, where she became entangled in a bitter feud with Tiberius. The conflict eventually led to the destruction of her family, with Caligula as the sole male survivor. In 26, Tiberius withdrew from public life to the island of Capri, and in 31, Caligula joined him there. Fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germanicus
Germanicus Julius Caesar (24 May 15 BC – 10 October AD 19) was an ancient Roman general, known for his campaigns in Germania. The son of Nero Claudius Drusus and Antonia the Younger, Germanicus was born into an influential branch of the Patrician (ancient Rome), patrician ''gens Claudia''. The Victory title, agnomen ''Germanicus'' was added to his full name in 9 BC when it was posthumously awarded to his father in honour of his victories in Germania. In AD 4, he was adopted by his paternal uncle Tiberius, who succeeded Augustus as Roman emperor a decade later. As a result, Germanicus became an official member of the Julia gens, ''gens Julia'', another prominent family, to which he was related on his mother's side. His connection to the Julii was further consolidated through a marriage between himself and Agrippina the Elder, a granddaughter of Augustus. He was also the father of Caligula, the maternal grandfather of Nero, and the older brother of Claudius. During the reign of A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marcus Vipsanius Agrippa
Marcus Vipsanius Agrippa (; BC – 12 BC) was a Roman general, statesman, and architect who was a close friend, son-in-law, and lieutenant to the Roman emperor Augustus. He was responsible for the construction of some of the most notable buildings in history, including the original Pantheon, Rome, Pantheon, and is well known for his important military victories, notably the Battle of Actium in 31 BC against the forces of Mark Antony and Cleopatra. Born to a Plebs, plebeian Vipsania gens, family around 63 BC, in an uncertain location in Roman Italy, he met the future emperor Augustus, then known as Octavian, at Apollonia (Illyria), Apollonia, in Illyria. Following the Assassination of Julius Caesar, assassination of Octavian's great-uncle Julius Caesar in 44 BC, Octavian returned to Italy. Around this time, he was elected tribune of the plebs. Agrippa served as a military commander, fighting alongside Octavian and Caesar's former general and right-hand man Mark Antony in the Bat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Rome
In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 BC), Roman Republic (509–27 BC) and Roman Empire (27 BC–476 AD) until the fall of the western empire. Ancient Rome began as an Italic settlement, traditionally dated to 753 BC, beside the River Tiber in the Italian Peninsula. The settlement grew into the city and polity of Rome, and came to control its neighbours through a combination of treaties and military strength. It eventually dominated the Italian Peninsula, assimilated the Greek culture of southern Italy ( Magna Grecia) and the Etruscan culture and acquired an Empire that took in much of Europe and the lands and peoples surrounding the Mediterranean Sea. It was among the largest empires in the ancient world, with an estimated 50 to 90 million inhabitants, roughly 20% of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Albedo
Albedo (; ) is the measure of the diffuse reflection of 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 ''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 obtained from flux measurements) to ... [...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 cata ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wide-field Infrared Survey Explorer
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 cat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Akari (satellite)
Akari (ASTRO-F) was an infrared astronomy satellite developed by Japan Aerospace Exploration Agency, in cooperation with institutes of Europe and Korea. It was launched on 21 February 2006, at 21:28 UTC (06:28, 22 February JST) by M-V rocket into Earth sun-synchronous orbit. After its launch it was named ''Akari'' (明かり), which means ''light'' in Japanese. Earlier on, the project was known as IRIS (InfraRed Imaging Surveyor). Its primary mission was to survey the entire sky in near-, mid- and far-infrared, through its aperture telescope. Technical design Its designed lifespan, of far- and mid-infrared sensors, was 550 days, limited by its liquid helium coolant. Its telescope mirror was made of silicon carbide to save weight. The budget for the satellite was ¥13,4 billion (~). History By mid-August 2006, Akari finished around 50 percent of the all sky survey. By early November 2006, first (phase-1) all-sky survey finished. Second (phase-2) all-sky survey started ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotation Period
The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the background stars, measured in sidereal time. The other type of commonly used rotation period is the object's synodic rotation period (or ''solar day''), measured in solar time, which may differ by a fraction of a rotation or more than one rotation to accommodate the portion of the object's orbital period during one day. Measuring rotation For solid objects, such as rocky planets and asteroids, the rotation period is a single value. For gaseous or fluid bodies, such as stars and gas giants, the period of rotation varies from the object's equator to its pole due to a phenomenon called differential rotation. Typically, the stated rotation period for a gas giant (such as Jupiter, Saturn, Uranus, Neptune) is its internal rotation period, as d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
