Wide-field Infrared Survey Explorer
Wide-field Infrared Survey Explorer is a NASA infrared-wavelength astronomical space telescope launched in December 2009, placed in hibernation mode in February 2011. It was re-activated in 2013. WISE discovered thousands of numerous star clusters, its observations supported the discovery of the first Y 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 40 cm diameter infrared telescope in Earth orbit. After its hydrogen coolant depleted, a four-month mission extension called NEOWISE was conducted to search for near-Earth objects such as comets and asteroids using its remaining capability; the All-Sky data including processed images, source catalogs and raw data, was released to the public on March 14, 2012, is available at the Infrared Science Archive. In August 2013, NASA announced it would reactivate the WISE telescope for a new three-year mission to search for asteroids that could collide with Earth.
Science operations and data processing for WISE and NEOWISE take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. The mission was planned to create infrared images of 99 percent of the sky, with at least eight images made of each position on the sky in order to increase accuracy; the spacecraft was placed in a 525 km, polar, Sun-synchronous orbit for its ten-month mission, during which it has taken 1.5 million images, one every 11 seconds. The satellite orbited above the terminator, its telescope pointing always to the opposite direction to the Earth, except for pointing towards the Moon, avoided, its solar cells towards the Sun; each image covers a 47-arcminute field of view. Each area of the sky was scanned at least 10 times at the equator; the produced image library contains data on the local Solar System, the Milky Way, the more distant universe. Among the objects WISE studied are asteroids, dim stars such as brown dwarfs, the most luminous infrared galaxies.
Stellar nurseries, which are covered by interstellar dust, are detectable in infrared, since at this wavelength electromagnetic radiation can penetrate the dust. Infrared measurements from the WISE astronomical survey have been effective at unveiling undiscovered star clusters. Examples of such embedded star clusters are Camargo 18, Camargo 440, Majaess 101, Majaess 116. In addition, galaxies of the young Universe and interacting galaxies, where star formation is intensive, are bright in infrared. On this wavelength the interstellar gas clouds are detectable, as well as proto-planetary discs. WISE satellite was expected to find at least 1,000 of those proto-planetary discs. WISE was not able to detect Kuiper belt objects, it was able to detect any objects warmer than 70–100 K. A Neptune-sized object would be detectable out to 700 AU, a Jupiter-mass object out to 1 light year, where it would still be within the Sun's zone of gravitational control. A larger object of 2–3 Jupiter masses would be visible at a distance of up to 7–10 light years.
At the time of planning, it was estimated that WISE would detect about 300,000 main-belt asteroids, of which 100,000 will be new, some 700 near-Earth objects including about 300 undiscovered. That translates to about 1000 new main-belt asteroids per day, 1–3 NEOs per day; the peak of magnitude distribution for NEOs will be about 21–22 V. WISE would detect each typical Solar System object 10–12 times over about 36 hours in intervals of 3 hours. Construction of the WISE telescope was divided between Ball Aerospace & Technologies, SSG Precision Optronics, Inc. DRS and Rockwell, Lockheed Martin, Space Dynamics Laboratory; the program was managed through the Jet Propulsion Laboratory. The WISE instrument was built by the Space Dynamics Laboratory in Utah; the WISE spacecraft bus was built by Technologies Corp. in Boulder, Colorado. The spacecraft is derived from the Ball Aerospace RS-300 spacecraft architecture the NEXTSat spacecraft built for the successful Orbital Express mission launched on March 9, 2007.
The flight system has an estimated mass of 560 kg. The spacecraft is three-axis stabilized, with body-fixed solar arrays, it uses a high-gain antenna in the Ku band to transmit to the ground through the TDRSS geostationary system. Ball performed the testing and flight system integration. WISE surveyed the sky in four wavelengths of the infrared band, at a high sensitivity, its design specified as goals that the full sky atlas of stacked images it produced have 5-sigma sensitivity limits of 120, 160, 650, 2600 microjanskies at 3.3, 4.7, 12, 23 micrometers. WISE achieved at least 68, 98, 860, 5400 µJy 5-sigma sensitivity at 3.4, 4.6, 12, 22 micrometers for the WISE All-Sky data release. This is a factor of 1,000 times better sensitivity than the survey completed in 1983 by the IRAS satellite in the 12 and 23 micrometers bands, a factor of 500,000 times better than the 1990s survey by the Cosmic Background Explorer satellite at 3.3 and 4.7 micrometers. On the other hand, IRAS could observe 60 and 100 micron wavelengths.
Band 1 – 3.4 micrometers – broad-band sensitivity to stars and galaxies Band 2 – 4.6 micrometers – detect thermal radiation from the internal heat sources of sub-stell
The orbital eccentricity of an astronomical object is a 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, 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 used for the isolated two-body problem, but extensions exist for objects following a Klemperer rosette orbit through the galaxy. 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. The eccentricity may take the following values: circular orbit: e = 0 elliptic orbit: 0 < e < 1 parabolic trajectory: e = 1 hyperbolic trajectory: e > 1 The eccentricity e is given by e = 1 + 2 E L 2 m red α 2 where E is the total orbital energy, L is the angular momentum, mred is the reduced mass, α the coefficient of the inverse-square law central force such as gravity or electrostatics in classical physics: F = α r 2 or in the case of a gravitational force: e = 1 + 2 ε h 2 μ 2 where ε is the specific orbital energy, μ the standard gravitational parameter based on the total mass, h the specific relative angular momentum.
For values of e from 0 to 1 the orbit's shape is an elongated ellipse. The limit case between an ellipse and a hyperbola, when e equals 1, is parabola. Radial trajectories are classified as elliptic, parabolic, or hyperbolic based on the energy of the orbit, not the eccentricity. Radial orbits hence eccentricity equal to one. Keeping the energy constant and reducing the angular momentum, elliptic and hyperbolic orbits each tend to the corresponding type of radial trajectory while e tends to 1. For a repulsive force only the hyperbolic trajectory, including the radial version, is applicable. For elliptical orbits, a simple proof shows that arcsin yields the projection angle of a perfect circle to an ellipse of eccentricity e. For example, to view the eccentricity of the planet Mercury, one must calculate the inverse sine to find the projection angle of 11.86 degrees. Next, tilt any circular object by that angle and the apparent ellipse projected to your eye will be of that same eccentricity; the word "eccentricity" comes from Medieval Latin eccentricus, derived from Greek ἔκκεντρος ekkentros "out of the center", from ἐκ- ek-, "out of" + κέντρον kentron "center".
"Eccentric" first appeared in English in 1551, with the definition "a circle in which the earth, sun. Etc. deviates from its center". By five years in 1556, an adjectival form of the word had developed; the eccentricity of an orbit can be calculated from the orbital state vectors as the magnitude of the eccentricity vector: e = | e | where: e is the eccentricity vector. For elliptical orbits it can be calculated from the periapsis and apoapsis since rp = a and ra = a, where a is the semimajor axis. E = r a − r p r a + r p = 1 − 2 r a r p + 1 where: ra is the radius at apoapsis. Rp is the radius at periapsis; the eccentricity of an elliptical orbit can be used to obtain the ratio of the periapsis to the apoapsis: r p r a = 1 − e 1 + e For Earth, orbital eccentricity ≈ 0.0167, apoapsis= aphelion and periapsis= perihelion relative to sun. For Earth's annual orbit path, ra/rp ratio = longest_radius / shortest_radius ≈ 1.034 relative to center point of path. The eccentricity of the Earth's orbit is about 0.0167.
David H. Levy
David H. Levy is a Canadian astronomer, science writer and discoverer of comets and minor planets, who co-discovered Comet Shoemaker–Levy 9 in 1993, which collided with the planet Jupiter in 1994. Levy was born in Montreal, Canada, in 1948, he developed an interest in astronomy at an early age. However, he received bachelor's and master's degrees in English literature. Levy went on to discover 22 comets, either independently or with Carolyn Shoemaker, he has written 34 books on astronomical subjects, such as The Quest for Comets, a biography of Pluto-discoverer Clyde Tombaugh in 2006, his tribute to Gene Shoemaker in Shoemaker by Levy. He has provided periodic articles for Sky and Telescope magazine, as well as Parade Magazine, Sky News and, most Astronomy Magazine. Periodic comets that Levy co-discovered include 118P/Shoemaker–Levy, 129P/Shoemaker–Levy, 135P/Shoemaker–Levy, 137P/Shoemaker–Levy, 138P/Shoemaker–Levy, 145P/Shoemaker–Levy, 181P/Shoemaker–Levy. In addition, Levy is the sole discoverer of two periodic comets: 255P/Levy and P/1991 L3.
On February 28, 2010, Levy was awarded a Ph. D. from the Hebrew University of Jerusalem for his successful completion of his thesis "The Sky in Early Modern English Literature: A Study of Allusions to Celestial Events in Elizabethan and Jacobean Writing, 1572–1620." Starting in 2015, Levy has been donating his observing logs, which he has kept continuously since 1956, his personal journals since 1958, his comet search records since 1965, to the Linda Hall Library of Science Library in Kansas City. The observing records are on-line at the website of the Royal Astronomical Society of Canada, he is married to Wendee Levy. Levy and his wife hosted a weekly internet radio talk show on astronomy, which ended on February 3, 2011, with a planned "Final Show". Show archives are available in MP3 formats. Levy is President of the National Sharing the Sky Foundation and a Master of Astronomy with DeTao Masters Academy; the main-asteroid 3673 Levy was named in his honour. Levy was awarded the C. A. Chant Medal of the Royal Astronomical Society of Canada in 1980.
Levy was recipient of the 1990 G. Bruce Blair Medal. In 1993 he won the Amateur Achievement Award of the Astronomical Society of the Pacific. In 2007, Levy received the Smithsonian Astrophysical Observatory's Edgar Wilson Award for the discovery of comets. In 2008, a special edition telescope, "The Comet Hunter" was co-designed by Levy. Together with Martyn Ives, David Taylor, Benjamin Woolley, Levy won a 1998 News & Documentary Emmy Award in the "Individual Achievement in a Craft, Writer" category for the script of the documentary 3 Minutes to Impact produced by York Films for the Discovery Channel. Visual Photographic, as part of team of Eugene and Carolyn Shoemaker and David Levy Nova Cygni 1975, August 30, 1975 Nova Cygni 1978, September 12, 1978 Comet Hartley-IRAS, November 30, 1983 Comet Shoemaker 1992y, C/1992 U1 Periodic Comet Shoemaker 4, 1994k, P/1994 J3 Asteroid Eureka, the first Martian Trojan asteroid, with Henry E. Holt, June 1990 Established the cataclysmically recurring nature of 1215-17 TV Corvi, August 1990 Carolyn S. Shoemaker Eugene Merle Shoemaker List of minor planet discoverers David Levy's Home Page
Naming of comets
Comets have been observed for the last 2,000 years. During that time, several different systems have been used to assign names to each comet, as a result many comets have more than one name; the simplest system names comets after the year. A convention arose of using the names of people associated with the discovery or the first detailed study of each comet. During the twentieth century, improvements in technology and dedicated searches led to a massive increase in the number of comet discoveries, which led to the creation of a numeric designation scheme; the original scheme assigned codes in the order. This scheme operated until 1994, when continued increases in the numbers of comets found each year resulted in the creation of a new scheme; this system, still in operation, assigns a code based on the type of orbit and the date of discovery. Before any systematic naming convention was adopted, comets were named in a variety of ways. Prior to the early 20th century, most comets were referred to by the year when they appeared e.g. the "Comet of 1702".
Bright comets which came to public attention would be described as the great comet of that year, such as the "Great Comet of 1680" and "Great Comet of 1882". If more than one great comet appeared in a single year, the month would be used for disambiguation e.g. the "Great January comet of 1910". Other additional adjectives might be used; the earliest comet to be named after a person was Caesar's Comet in 44 BC, so named because it was observed shortly after the assassination of Julius Caesar and was interpreted as a sign of his deification. Eponymous comets were named after the astronomer who conducted detailed investigations on them, or those who discovered the comet. After Edmond Halley demonstrated that the comets of 1531, 1607, 1682 were the same body and predicted its return in 1759, that comet became known as Halley's Comet; the second and third known periodic comets, Encke's Comet and Biela's Comet, were named after the astronomers who calculated their orbits rather than their original discoverers.
Periodic comets were named after their discoverers, but comets that had appeared only once continued to be referred to by the year of their apparition. The first comet to be named after the person who discovered it, rather than the one who calculated its orbit, was Comet Faye – discovered by Hervé Faye in 1843. However, this convention did not become widespread until the early 20th century, it remains common today. A comet can be named after up to three discoverers, either working together as a team or making independent discoveries. For example, Comet Swift–Tuttle was first found by Lewis Swift and by Horace Parnell Tuttle a few days later. In recent years many comets have been discovered by large teams of astronomers, in this case comets may be named for the collaboration or instrument they used. For example, 160P/LINEAR was discovered by the Lincoln Near-Earth Asteroid Research team. Comet IRAS–Araki–Alcock was discovered independently by a team using the Infrared Astronomy Satellite and the amateur astronomers Genichi Araki and George Alcock.
In the past, when multiple comets were discovered by the same individual, group of individuals, or team, the comets' names were distinguished by adding a numeral to the discoverers' names. Today, the large numbers of comets discovered by some instruments makes this system impractical, no attempt is made to ensure that each comet is given a unique name. Instead, the comets' systematic designations are used to avoid confusion; until 1994, comets were first given a provisional designation consisting of the year of their discovery followed by a lowercase letter indicating its order of discovery in that year. Once the comet had been observed through perihelion and its orbit had been established, the comet was given a permanent designation of the year of its perihelion, followed by a Roman numeral indicating its order of perihelion passage in that year, so that Comet 1969i became Comet 1970 II Increasing numbers of comet discoveries made this procedure awkward, as did the delay between discovery and perihelion passage before the permanent name could be assigned.
As a result, in 1994 the International Astronomical Union approved a new naming system. Comets are now designated by the year of their discovery followed by a letter indicating the half-month of the discovery and a number indicating the order of discovery. For example, the fourth comet discovered in the second half of February 2006 was designated 2006 D4. Prefixes are added to indicate the nature of the comet: P/ indicates a periodic comet. C/ indicates a non-periodic comet. X / indicates a comet. D / indicates a periodic comet that has broken up, or been lost. A/ indicates an object, mistakenly identified as a comet, but is ac
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, but two-and-a-half times that of all the other planets in the Solar System combined. Jupiter and Saturn are gas giants. Jupiter has been known to astronomers since antiquity, it is named after the Roman god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, bright enough for its reflected light to cast shadows, making it on average the third-brightest natural object in the night sky after the Moon and Venus. Jupiter is composed of hydrogen with a quarter of its mass being helium, though helium comprises only about a tenth of the number of molecules, it may have a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. Because of its rapid rotation, the planet's shape is that of an oblate spheroid; the outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries.
A prominent result is the Great Red Spot, a giant storm, known to have existed since at least the 17th century when it was first seen by telescope. Surrounding Jupiter is a powerful magnetosphere. Jupiter has 79 known moons, including the four large Galilean moons discovered by Galileo Galilei in 1610. Ganymede, the largest of these, has a diameter greater than that of the planet Mercury. Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and by the Galileo orbiter. In late February 2007, Jupiter was visited by the New Horizons probe, which used Jupiter's gravity to increase its speed and bend its trajectory en route to Pluto; the latest probe to visit the planet is Juno, which entered into orbit around Jupiter on July 4, 2016. Future targets for exploration in the Jupiter system include the probable ice-covered liquid ocean of its moon Europa. Astronomers have discovered nearly 500 planetary systems with multiple planets.
These systems include a few planets with masses several times greater than Earth's, orbiting closer to their star than Mercury is to the Sun, sometimes Jupiter-mass gas giants close to their star. Earth and its neighbor planets may have formed from fragments of planets after collisions with Jupiter destroyed those super-Earths near the Sun; as Jupiter came toward the inner Solar System, in what theorists call the grand tack hypothesis, gravitational tugs and pulls occurred causing a series of collisions between the super-Earths as their orbits began to overlap. Researchers from Lund University found that Jupiter's migration went on for around 700,000 years, in a period 2-3 million years after the celestial body started its life as an ice asteroid far from the sun; the journey inwards in the solar system followed a spiraling course in which Jupiter continued to circle around the sun, albeit in an tight path. The reason behind the actual migration relates to gravitational forces from the surrounding gases in the solar system.
Jupiter moving out of the inner Solar System would have allowed the formation of inner planets, including Earth. Jupiter is composed of gaseous and liquid matter, it is the largest of hence its largest planet. It has a diameter of 142,984 km at its equator; the average density of Jupiter, 1.326 g/cm3, is the second highest of the giant planets, but lower than those of the four terrestrial planets. Jupiter's upper atmosphere is about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules. A helium atom has about four times as much mass as a hydrogen atom, so the composition changes when described as the proportion of mass contributed by different atoms. Thus, Jupiter's atmosphere is 75% hydrogen and 24% helium by mass, with the remaining one percent of the mass consisting of other elements; the atmosphere contains trace amounts of methane, water vapor and silicon-based compounds. There are traces of carbon, hydrogen sulfide, oxygen and sulfur; the outermost layer of the atmosphere contains crystals of frozen ammonia.
The interior contains denser materials—by mass it is 71% hydrogen, 24% helium, 5% other elements. Through infrared and ultraviolet measurements, trace amounts of benzene and other hydrocarbons have been found; the atmospheric proportions of hydrogen and helium are close to the theoretical composition of the primordial solar nebula. Neon in the upper atmosphere only consists of 20 parts per million by mass, about a tenth as abundant as in the Sun. Helium is depleted to about 80% of the Sun's helium composition; this depletion is a result of precipitation of these elements into the interior of the planet. Based on spectroscopy, Saturn is thought to be similar in composition to Jupiter, but the other giant planets Uranus and Neptune have less hydrogen and helium and more ices and are thus now termed ice giants. Jupiter's mass is 2.5 times that of all the other planets in the Solar System combined—this is so massive that its barycenter with the Sun lies above the Sun's surface at 1.068 solar radii from the Sun's center.
Jupiter is much larger than Earth and less dense: its volume is that of about 1,321 Earths, but it is only 318 times as massive. Jupiter's radius is about 1/10 the radius of the Sun, its mass is 0.001 times the mass of the Sun, so the densities of the two bodies are similar. A "Jupiter mass" is used as a u
The Panoramic Survey Telescope and Rapid Response System located at Haleakala Observatory, Hawaii, USA, consists of astronomical cameras, telescopes and a computing facility, surveying the sky for moving or variable objects on a continual basis, producing accurate astrometry and photometry of already-detected objects. In January 2019 the second Pan-STARRS data release was announced. At 1.6 petabytes, it is the largest volume of astronomical data released. The Pan-STARRS Project is a collaboration between the University of Hawaii Institute for Astronomy, MIT Lincoln Laboratory, Maui High Performance Computing Center and Science Applications International Corporation. Telescope construction was funded by the U. S. Air Force. By detecting differences from previous observations of the same areas of the sky, Pan-STARRS is discovering a large number of new asteroids, variable stars and other celestial objects, its primary mission is now to detect Near-Earth Objects that threaten impact events and it is expected to create a database of all objects visible from Hawaii down to apparent magnitude 24.
Construction of Pan-STARRS was funded in large part by the United States Air Force through their Research Labs. Additional funding to complete Pan-STARRS2 came from the NASA Near Earth Object Observation Program. Most of the funding presently used to operate the Pan-STARRS telescopes comes from the NASA Near Earth Object Observation Program; the Pan-STARRS NEO survey searches all the sky north of declination −47.5. The first Pan-STARRS telescope is located at the summit of Haleakalā on Maui and went online on December 6, 2008, under the administration of the University of Hawaii. PS1 began full-time science observations on May 13, 2010, the PS1 Science Mission ran until March 2014. Operations were funded by the PS1 Science Consortium, PS1SC, a consortium including the Max Planck Society in Germany, National Central University in Taiwan, Edinburgh and Queen's Belfast Universities in the UK, Johns Hopkins and Harvard Universities in the United States and the Las Cumbres Observatory Global Telescope Network.
Consortium observations for the all sky survey were completed in April 2014. Having completed PS1, the Pan-STARRS Project focused on building Pan-STARRS 2, for which first light was achieved in 2013, with full science operations scheduled for 2014 and the full array of four telescopes, sometimes called PS4. Completing the array of four telescopes is estimated at a total cost of US$100 million for the entire array; as of mid-2014, Pan-STARRS 2 was in the process of being commissioned. In the wake of substantial funding problems, no clear timeline existed for additional telescopes beyond the second. In March 2018, Pan-STARRS 2 was credited by the Minor Planet Center for the discovery of the hazardous Apollo asteroid 2015 JA2, its first minor-planet discovery made at Haleakala on 13 May 2015. Pan-STARRS consists of two 1.8 m Ritchey–Chrétien telescopes located at Haleakala in Hawaii. The initial telescope, PS1, saw first light using a low-resolution camera in June 2006; the telescope has a 3° field of view, large for telescopes of this size, is equipped with the largest digital camera built, recording 1.4 billion pixels per image.
The focal plane has 60 separately mounted close packed CCDs arranged in an 8 × 8 array. The corner positions are not populated; each CCD device, called an Orthogonal Transfer Array, has 4800 × 4800 pixels, separated into 64 cells, each of 600 × 600 pixels. This gigapixel camera or ` GPC' saw first light on August 2007, imaging the Andromeda Galaxy. After initial technical difficulties that were mostly solved, PS1 began full operation on May 13, 2010. Nick Kaiser, principal investigator of the Pan-STARRS project, summed it up saying “PS1 has been taking science-quality data for six months, but now we are doing it dusk-to-dawn every night.”. The PS1 images however remain less sharp than planned, which affects some scientific uses of the data; each image requires about 2 gigabytes of storage and exposure times will be 30 to 60 seconds, with an additional minute or so used for computer processing. Since images will be taken on a continuous basis, it is expected that 10 Terabytes of data will be acquired by PS4 every night.
Comparing against a database of known unvarying objects compiled from earlier observations will yield objects of interest: anything that has changed brightness and/or position for any reason. As of June 30/10 University of Hawaii in Honolulu received an $8.4 million contract modification under the PanSTARRS multi-year program to develop and deploy a telescope data management system for the project. At this time, all funds have been committed The large field of view of the telescopes and the short exposure times enable 6000 square degrees of sky to be imaged every night; the entire sky is 4π steradians, or 4π × ² ≈ 41,253.0 square degrees, of which about 30,000 square degrees are visible from Hawaii, which means that the entire sky can be imaged in a period of 40 hours. Given the need to avoid times when the Moon is bright, this means that an area equivalent to the entire sky will be surveyed four times a month, unprecedented. By the end of its initial three-year mission in April 2014, PS1 had imaged the sky 12 times in each of 5 filters.
Pan-STARRS is mostly funded by a grant
William A. Bradfield
William Ashley Bradfield was a New Zealand-born Australian amateur astronomer, notable as a prolific amateur discoverer of comets. He gained a world record by discovering 18 comets, all of which bear his name as the sole discoverer, his astronomical achievements were summed up by Brian G. Marsden, director emeritus of the IAU's Central Bureau for Astronomical Telegrams: "To discover 18 comets visually is an extraordinary accomplishment in any era, but to do so now is remarkable, I think we can be pretty sure nobody will be able to do it again, and it's all the more astounding that in no case did he have to share a discovery with some other independent discoverer. More than any other recipient, Bill Bradfield outstandingly deserves the Edgar Wilson Award." Bradfield was born in Levin, New Zealand on 20 June 1927. He grew up on a dairy farm, where his interests in rocketry and astronomy first developed, when he was 15 he got his first small telescope, he attended the University of New Zealand, where he graduated with a bachelor's degree in Mechanical Engineering.
He spent 2 years in England doing a rocket propulsion residency and in 1953 he moved to Australia, taking up residence in Adelaide, where he worked for the Australian Department of Defence as a rocket propulsion engineer and research scientist until he retired in 1986. This was where he met Eileen. Bradfield joined the Astronomical Society of South Australia in 1970 which fueled his interest, he started hunting for comets in 1971, using a second-hand telescope which he bought from another ASSA member. Just over a year and 260 hours of searching he was rewarded with finding Comet Bradfield. Six comets followed in his first six years, in 1987 the discovery of his 13th comet made him the most prolific comet-hunter of the 20th century, his count built to 18 comets after 3500 hours of searching, with the 18th and final comet discovery coming on 23 March 2004 when he was 76 years old. When Bradfield discovered a comet and communicated it to the International Astronomical Union, it kicked off worldwide action.
Within 14 hours of reporting his 17th comet in 1995, it had been observed by more than 20 observers, including the European Southern Observatory 1-meter Schmidt telescope at La Silla, Chile. His discoveries were notable because he worked alone to discover them, using old and home-made telescopic equipment. Apart from the 100-year-old lens and modern eyepieces, the remainder of his telescope was homemade, but suited for hunting comets, he did not use photographic or computerized detection equipment, relying instead on purely visual sweeping across the skies. Having joined the Astronomical Society of South Australia in 1970, Bradfield served as its President from 1977 to 1979. In 1989 he was appointed an honorary Life Member, he was inducted into the ASSA Hall of Fame in 2013, he died on 9 June 2014 after a long illness, at age 86. Asteroid 3430 Bradfield was named in his honour. Bradfield received the Berenice and Arthur Page Medal from the Astronomical Society of Australia in 1981, he was made a member of the Order of Australia "in recognition of his service to astronomy" in 1989.
He was made an Honorary Life Member of the Astronomical Society of South Australia in 1989. In 2000 the Astronomical Society of South Australia created the Bill Bradfield Astronomy Award in honour of his achievements, given to an amateur who displays exceeding accomplishment in a given year in the field of astronomy, he was awarded the Edgar Wilson Award from the Smithsonian Astrophysical Observatory through the IAU's Central Bureau for Astronomical Telegrams in 2004. In 2013 he was inducted into the ASSA Hall of Fame. Comet: Initial designation of the comet Hours: Number of search hours for discovery Date: Discovery date in UT Mag: Total magnitude of comet at discovery