The orbits of the Halley-type comets suggest that they were originally long-period comets whose orbits were perturbed by the gravity of the giant planets and directed into the inner Solar System. [42] If Halley was once a long-period comet, it is likely to have originated in the Oort cloud, [43] a sphere of cometary bodies around 20,000–50,000 au from the Sun. Conversely the Jupiter-family comets are generally believed to originate in the Kuiper belt, [43] a flat disc of icy debris between 30 au (Neptune's orbit) and 50 au from the Sun (in the scattered disc). Another point of origin for the Halley-type comets was proposed in 2008, when a trans-Neptunian object with a retrograde orbit similar to Halley's was discovered, 2008 KV 42, whose orbit takes it from just outside that of Uranus to twice the distance of Pluto. It may be a member of a new population of small Solar System bodies that serves as the source of Halley-type comets. [45] Halley's calculations enabled the comet's earlier appearances to be found in the historical record. The following table sets out the astronomical designations for every apparition of Halley's Comet from 240BC, the earliest documented widespread sighting. [7] [136] For example, "1P/1982U1, 1986III, 1982i" indicates that for the perihelion in 1986, Halley was the first period comet known (designated 1P) and this apparition was the first seen in half-month U (the second half of October) [137] in 1982 (giving 1P/1982 U1); it was the third comet past perihelion in 1986 (1986 III); and it was the ninth comet spotted in 1982 ( provisional designation 1982i). The perihelion dates of each apparition are shown. [138] The perihelion dates farther from the present are approximate, mainly because of uncertainties in the modelling of non-gravitational effects. Perihelion dates of 1531 and earlier are in the Julian calendar, while perihelion dates 1607 and after are in the Gregorian calendar. [139] Designation While it will be decades before we can send another spacecraft to Halley's Comet, there have several other missions that have studied comets from up close. Between 2014 and 2016, for example, the Rosetta probe examined Comet 67P/Churyumov–Gerasimenko up close and made comparisons to other comets.

The comet was used in an advertising campaign of Le Bon Marché, a well-known department store in Paris. [109]Seen by Peter Apian, who noted that its tail always pointed away from the Sun. This sighting was included in Halley's table. The comet added to the unrest in China on the eve of the Xinhai Revolution that would end the last dynasty in 1911. As James Hutson, a missionary in Sichuan Province at the time, recorded,

The elevators are major pieces of technology in the sequel novel 3001, and settings of much of the latter novel's action. The intervening implication is that over the next millennium, humanity finds other large sources of diamond in the Lucifer–Jupiter system, precipitate which resulted from the transformation of the latter into the former, and mines this diamond material, using it for (previously impossible) construction projects. In 1989, Boris Chirikov and Vitold Vecheslavov performed an analysis of 46 apparitions of Halley's Comet taken from historical records and computer simulations. These studies showed that its dynamics were chaotic and unpredictable on long timescales. [48] Halley's projected lifetime could be as long as 10million years. These studies also showed that many physical properties of Halley's Comet dynamics can be approximately described by a simple symplectic map, known as the Kepler map. [49] More recent work suggests that Halley will evaporate, or split in two, within the next few tens of thousands of years, or will be ejected from the Solar System within a few hundred thousand years. [50] [43] Observations by D. W. Hughes suggest that Halley's nucleus has been reduced in mass by 80 to 90% over the last 2,000 to 3,000 revolutions. [18] Structure and composition [ edit ] The nucleus of Halley's Comet, imaged by the Giotto probe in 1986. The dark coloration of the nucleus can be observed, as well as the jets of dust and gas erupting from its surface. For soft Brexit, we took the long-term assumption for net international migration in the national population projections of the Office for National Statistics, based on the population at the end of June 2014. Our model assumed that the free movement of EU citizens would continue, but that a combination of factors would make the UK less attractive to migrants. Under this scenario, the UK population would continue to grow, but at a slower rate than the no Brexit scenario, and by 2061 the total population is projected to be 82.9m.Halley may have been recorded as early as 467BC, but this is uncertain. A comet was recorded in ancient Greece between 468 and 466 BC; its timing, location, duration, and associated meteor shower all suggest it was Halley. [58] According to Pliny the Elder, that same year a meteorite fell in the town of Aegospotami, in Thrace. He described it as brown in colour and the size of a wagon load. [59] Chinese chroniclers also mention a comet in that year. [60] Report of Halley's Comet by Chinese astronomers in 240 BC ( Shiji) Sam Benstead breaks down why investors are fleeing the bond market – and explains why that could actually be a good thing. The approach of the comet was first detected by astronomers David C. Jewitt and G. Edward Danielson on 16 October 1982 using the 5.1m Hale telescope at Mount Palomar and a CCD camera. [120] Fernández, Yanga R. (28 July 2015). "List of Jupiter-Family and Halley-Family Comets". University of Central Florida: Physics . Retrieved 6 September 2015.

Lages, José; Shepelyansky, Dima L.; Shevchenko, Ivan I. (2018). "Kepler map". Scholarpedia. 13 (2): 33238. Bibcode: 2018SchpJ..1333238L. doi: 10.4249/scholarpedia.33238. The Giotto and Vega missions gave planetary scientists their first view of Halley's surface and structure. Like all comets, as Halley nears the Sun, its volatile compounds (those with low boiling points, such as water, carbon monoxide, carbon dioxide and other ices) begin to sublimate from the surface of its nucleus. [51] This causes the comet to develop a coma, or atmosphere, up to 100,000 kilometres (62,000mi) across. [8] Evaporation of this dirty ice releases dust particles, which travel with the gas away from the nucleus. Gas molecules in the coma absorb solar light and then re-radiate it at different wavelengths, a phenomenon known as fluorescence, whereas dust particles scatter the solar light. Both processes are responsible for making the coma visible. [15] As a fraction of the gas molecules in the coma are ionized by the solar ultraviolet radiation, [15] pressure from the solar wind, a stream of charged particles emitted by the Sun, pulls the coma's ions out into a long tail, which may extend more than 100millionkilometres into space. [51] [52] Changes in the flow of the solar wind can cause disconnection events, in which the tail completely breaks off from the nucleus. [17]I came in with Halley's comet in 1835. It is coming again next year, and I expect to go out with it. It will be the greatest disappointment of my life if I don't go out with Halley's comet. The Almighty has said, no doubt: 'Now here are these two unaccountable freaks; they came in together, they must go out together.' [111] [112] While bond owners profited, the almost non-existent yields took bonds off the menu for many investors who wanted an income from their “fixed income” investments. And who can blame them? Why would you lend money to a company or a government that would guarantee you a loss in real terms, or after inflation? Slaje, Walter; inter alia, realia: "An Apparition of Halley's Comet in Kashmir observed by Śrīvara in AD 1456" in Steiner, Roland (ed.); Highland Philology: Results of a Text-Related Kashmir Panel at the 31st DOT, Marburg 2010, Studia Indologica Universitatis Halensis, 4, Halle 2012: 33–48 The next perihelion of Halley's Comet is 28 July 2061, [4] [5] when it will be better positioned for observation than during the 1985–1986 apparition, as it will be on the same side of the Sun as Earth. [38] The closest approach to Earth will be one day after perihelion. [7] It is expected to have an apparent magnitude of −0.3, compared with only +2.1 for the 1986 apparition. [135] On 9 September 2060, Halley will pass within 0.98au (147,000,000km) of Jupiter, and then on 20 August 2061 will pass within 0.0543au (8,120,000km) of Venus. [7] 2134 [ edit ] Two U.S. Space Shuttle missions— STS-51-L and STS-61-E—had been scheduled to observe Halley's Comet from low Earth orbit. The STS-51-L mission carried the Shuttle-Pointed Tool for Astronomy ( SPARTAN-203) satellite, also called the Halley's Comet Experiment Deployable (HCED). [130] The mission ended in disaster when the Space Shuttle Challenger exploded in flight, killing all seven astronauts onboard. [131] Scheduled for March 1986, STS-61-E was a Columbia mission carrying the ASTRO-1 platform to study the comet, [132] but the mission was canceled following the Challenger disaster and ASTRO-1 would not fly until late 1990 on STS-35. [133] After 1986 [ edit ] Halley's Comet observed in 2003 at 28 au from the Sun

The comet was also sketched by F.W. Bessel. [93] Streams of vapour observed during the comet's 1835 apparition prompted astronomer Friedrich Wilhelm Bessel to propose that the jet forces of evaporating material could be great enough to significantly alter a comet's orbit. [94] Population growth is a key driver of demand for housing, infrastructure, school places, health care and consumption, and so population projections are essential for the effective planning of these services. Of the components which make up these projections, international migration is the least predictable, yet has a large impact on the size and composition of the population. Our scenarios therefore used different assumptions about future immigration policy.But, in the short term the Federal Reserve is in play still and is playing hard. So it might be wise to wait and get paid somewhat lower yields with less risk, or by still owning short-dated inflation-linked bonds to receive the inflation that is higher than we thought it was going to be just a few months ago.” Mitra, Umasankar (1987). "An Investigation Into the Association Between Eta-Aquarid Meteor Shower and Halley's Comet". Bulletin of the Astronomical Society of India. 15: 23. Bibcode: 1987BASI...15...23M. In the years that followed, an era of unequaled peace and prosperity flourished in the silent presence of the aliens. Man continued to expand slowly into the solar system, careful not to violate the alien’s injunction--until a report is received that a spaceship has crashed into Europa’s ocean and is floating helplessly. Heywood Floyd, head of the American contingent of the 2010 Leonov expedition--still hale and hearty after all these years because of the age-retarding effects of his zero-gravity orbiting rest home -- finds himself thrown into the action when the Halley’s comet expedition on which he has been invited is diverted onto a high-speed sprint to Europa and a rescue attempt.