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Hartley 2
Comet Hartley 2, designated as 103P/Hartley by the Minor Planet Center, is a small periodic comet with an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia. Its diameter is estimated to be . Hartley 2 was the target of a flyby of the Deep Impact spacecraft, as part of the EPOXI mission, on 4 November 2010, which was able to approach within of Hartley 2 as part of its extended mission. Hartley 2 is the smallest comet which has been visited. It is the fifth comet visited by spacecraft, and the second comet visited by the Deep Impact spacecraft, which first visited comet Tempel 1 on 4 July 2005. Discovery and orbit Comet Hartley 2 is a small Jupiter-family comet having an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia. It has the perihelion near the Earth's orbit at 1.05 AU from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Hartley 2
Comet Hartley 2, designated as 103P/Hartley by the Minor Planet Center, is a small periodic comet with an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia. Its diameter is estimated to be . Hartley 2 was the target of a flyby of the Deep Impact spacecraft, as part of the EPOXI mission, on 4 November 2010, which was able to approach within of Hartley 2 as part of its extended mission. Hartley 2 is the smallest comet which has been visited. It is the fifth comet visited by spacecraft, and the second comet visited by the Deep Impact spacecraft, which first visited comet Tempel 1 on 4 July 2005. Discovery and orbit Comet Hartley 2 is a small Jupiter-family comet having an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia. It has the perihelion near the Earth's orbit at 1.05 AU from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tempel 1
Tempel 1 (official designation: 9P/Tempel) is a periodic Jupiter-family comet discovered by Wilhelm Tempel in 1867. It completes an orbit of the Sun every 5.5 years. Tempel 1 was the target of the ''Deep Impact'' space mission, which photographed a deliberate high-speed impact upon the comet in 2005. It was re-visited by the ''Stardust'' spacecraft on February 14, 2011 and came back to perihelion in August 2016. Discovery and orbital history Tempel 1 was discovered on April 3, 1867, by Wilhelm Tempel, who was working at Marseille. At the time of discovery, it approached perihelion once every 5.68 years (designations 9P/1867 G1 and 1867 II). It was subsequently observed in 1873 (9P/1873 G1, 1873 I, 1873a) and in 1879 (1879 III, 1879b). Photographic attempts during 1898 and 1905 failed to recover the comet, and astronomers surmised that it had disintegrated, when in reality, its orbit had changed. Tempel 1's orbit occasionally brings it sufficiently close to Jupiter to be al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cometary Nucleus
The nucleus is the solid, central part of a comet, once termed a ''dirty snowball'' or an ''icy dirtball''. A cometary nucleus is composed of rock, dust, and frozen gases. When heated by the Sun, the gases sublime and produce an atmosphere surrounding the nucleus known as the coma. The force exerted on the coma by the Sun's radiation pressure and solar wind cause an enormous tail to form, which points away from the Sun. A typical comet nucleus has an albedo of 0.04. This is blacker than coal, and may be caused by a covering of dust. Results from the ''Rosetta'' and ''Philae'' spacecraft show that the nucleus of 67P/Churyumov–Gerasimenko has no magnetic field, which suggests that magnetism may not have played a role in the early formation of planetesimals. Further, the ALICE spectrograph on ''Rosetta'' determined that electrons (within above the comet nucleus) produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought ear ... [...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. Following two breaks in cables supporting the receiver platform in mid-2020, the NSF decommissioned the telescope. A partial collapse of the telescope occurred on December 1, 2020, before controlled demolition could be conducted. In 2022, the NSF announced the telescope will not be rebuilt, with an education ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar
Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds. Radar was developed secretly for military use by several countries in the period before and during World War II. A key development was the cavity magnetron in the United Kingdom, which allowed the creation of relatively small systems with sub-meter resolution ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Nucleus
The nucleus is the solid, central part of a comet, once termed a ''dirty snowball'' or an ''icy dirtball''. A cometary nucleus is composed of Rock (geology), rock, dust, and frozen gases. When heated by the Sun, the gases Sublimation (physics), sublime and produce an atmosphere surrounding the nucleus known as the Coma (cometary), coma. The force exerted on the coma by the Sun's radiation pressure and solar wind cause an enormous tail to form, which points away from the Sun. A typical comet nucleus has an Albedo#Astronomical albedo, albedo of 0.04. This is blacker than coal, and may be caused by a covering of dust. Results from the Rosetta (spacecraft), ''Rosetta'' and Philae (spacecraft), ''Philae'' spacecraft show that the nucleus of 67P/Churyumov–Gerasimenko has no magnetic field, which suggests that magnetism may not have played a role in the early formation of planetesimals. Further, the Rosetta (spacecraft)#Instruments, ALICE spectrograph on ''Rosetta'' determined that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet Nucleus
The nucleus is the solid, central part of a comet, once termed a ''dirty snowball'' or an ''icy dirtball''. A cometary nucleus is composed of Rock (geology), rock, dust, and frozen gases. When heated by the Sun, the gases Sublimation (physics), sublime and produce an atmosphere surrounding the nucleus known as the Coma (cometary), coma. The force exerted on the coma by the Sun's radiation pressure and solar wind cause an enormous tail to form, which points away from the Sun. A typical comet nucleus has an Albedo#Astronomical albedo, albedo of 0.04. This is blacker than coal, and may be caused by a covering of dust. Results from the Rosetta (spacecraft), ''Rosetta'' and Philae (spacecraft), ''Philae'' spacecraft show that the nucleus of 67P/Churyumov–Gerasimenko has no magnetic field, which suggests that magnetism may not have played a role in the early formation of planetesimals. Further, the Rosetta (spacecraft)#Instruments, ALICE spectrograph on ''Rosetta'' determined that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spitzer Space Telescope
The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, following IRAS (1983) and ISO (1995–1998). It was the first spacecraft to use an Earth-trailing orbit, later used by the Kepler planet-finder. The planned mission period was to be 2.5 years with a pre-launch expectation that the mission could extend to five or slightly more years until the onboard liquid helium supply was exhausted. This occurred on 15 May 2009. Without liquid helium to cool the telescope to the very low temperatures needed to operate, most of the instruments were no longer usable. However, the two shortest-wavelength modules of the IRAC camera continued to operate with the same sensitivity as before the helium was exhausted, and continued to be used into early 2020 in the Spitzer Warm Mission. During the warm missio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hartley2 By Deep Impact Closeup500747main -full Full
Hartley may refer to: Places Australia *Hartley, New South Wales *Hartley, South Australia **Electoral district of Hartley, a state electoral district Canada *Hartley Bay, British Columbia United Kingdom *Hartley, Cumbria *Hartley, Plymouth, Devon *Hartley Wespall, Hampshire *Hartley, Sevenoaks, Kent * Hartley, Tunbridge Wells, Kent *Hartley, Northumberland (Old Hartley), part of Seaton Sluice *New Hartley, Northumberland United States * Hartley, California *Hartley, Iowa * Hartley, Michigan *Hartley, South Dakota *Hartley, Texas *Hartley County, Texas *Brohard, West Virginia, also Hartley Zimbabwe *Chegutu, formerly Hartley People * Hartley (surname) * Hartley Burr Alexander, (1873–1939), American philosopher * Hartley Alleyne (born 1957), Barbadian cricketer * Hartley Booth (born 1946), British politician * Hartley Coleridge (1796–1849), English writer * Hartley Craig (1917–2007), Australian cricketer * Hartley Douglas Dent (1929–1993), Canadian politician ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambridge University Press
Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by Henry VIII of England, King Henry VIII in 1534, it is the oldest university press in the world. It is also the King's Printer. Cambridge University Press is a department of the University of Cambridge and is both an academic and educational publisher. It became part of Cambridge University Press & Assessment, following a merger with Cambridge Assessment in 2021. With a global sales presence, publishing hubs, and offices in more than 40 Country, countries, it publishes over 50,000 titles by authors from over 100 countries. Its publishing includes more than 380 academic journals, monographs, reference works, school and university textbooks, and English language teaching and learning publications. It also publishes Bibles, runs a bookshop in Cambridge, sells through Amazon, and has a conference venues business in Cambridge at the Pitt Building and the Sir Geoffrey Cass Spo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteor Showers
A meteor shower is a celestial event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extremely high speeds on parallel trajectories. Most meteors are smaller than a grain of sand, so almost all of them disintegrate and never hit the Earth's surface. Very intense or unusual meteor showers are known as meteor outbursts and meteor storms, which produce at least 1,000 meteors an hour, most notably from the Leonids. The Meteor Data Centre lists over 900 suspected meteor showers of which about 100 are well established. Several organizations point to viewing opportunities on the Internet. NASA maintains a daily map of active meteor showers. Historical developments A meteor shower in August 1583 was recorded in the Timbuktu manuscripts.Abraham, Curtis"Stars of the Sahara" ''New Scientist'', issue 2617,15 August 2007, page 39–41 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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