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74-481: The Perseids are a prolific meteor shower associated with the comet Swift–Tuttle that are usually visible from mid- July to late- August . The meteors are called the Perseids because they appear from the general direction of the constellation Perseus and in more modern times have a radiant bordering on Cassiopeia and Camelopardalis . The name is derived from the word Perseidai ( Greek : Περσείδαι ),

148-715: A Greek or Roman letter assigned that is close to the radiant position at the peak of the shower, whereby the grammatical declension of the Latin possessive form is replaced by "id" or "ids." Hence, meteors radiating from near the star Delta Aquarii (declension "-i") are called the Delta Aquariids . The International Astronomical Union's Task Group on Meteor Shower Nomenclature and the IAU's Meteor Data Center keep track of meteor shower nomenclature and which showers are established. A meteor shower results from an interaction between

222-408: A Greek root) were used by physicist and science-fiction author Geoffrey A. Landis in a story published in 1998, thus appearing before perinigricon and aponigricon (from Latin) in the scientific literature in 2002. The suffixes shown below may be added to prefixes peri- or apo- to form unique names of apsides for the orbiting bodies of the indicated host/ (primary) system. However, only for

296-488: A cloud of particles in space. Work continued, yet coming to understand the annual nature of showers though the occurrences of storms perplexed researchers. The actual nature of meteors was still debated during the 19th century. Meteors were conceived as an atmospheric phenomenon by many scientists ( Alexander von Humboldt , Adolphe Quetelet , Julius Schmidt ) until the Italian astronomer Giovanni Schiaparelli ascertained

370-490: A different epoch will generate differences. The time-of-perihelion-passage as one of six osculating elements is not an exact prediction (other than for a generic two-body model ) of the actual minimum distance to the Sun using the full dynamical model . Precise predictions of perihelion passage require numerical integration . The two images below show the orbits, orbital nodes , and positions of perihelion (q) and aphelion (Q) for

444-424: A greater frequency of these meteors in the month of August (from 8 to 15)." After studying historical records, he predicted a peak on 10 August. He then wrote to other astronomers, who confirmed this prediction on the night of 10 August 1837. Quetelet missed the shower due to bad weather. In 1866, after the perihelion passage of Swift-Tuttle in 1862, the Italian astronomer Giovanni Virginio Schiaparelli discovered

518-558: A mostly dormant comet. Examples are the Quadrantids and Geminids , which originated from a breakup of asteroid-looking objects, (196256) 2003 EH 1 and 3200 Phaethon , respectively, about 500 and 1000 years ago. The fragments tend to fall apart quickly into dust, sand, and pebbles and spread out along the comet's orbit to form a dense meteoroid stream, which subsequently evolves into Earth's path. Shortly after Whipple predicted that dust particles traveled at low speeds relative to

592-461: A planet, such as Earth, and streams of debris from a comet . Comets can produce debris by water vapor drag, as demonstrated by Fred Whipple in 1951, and by breakup. Whipple envisioned comets as "dirty snowballs," made up of rock embedded in ice, orbiting the Sun . The "ice" may be water , methane , ammonia , or other volatiles , alone or in combination. The "rock" may vary in size from a dust mote to

666-488: A shower component called a filament. A second effect is a close encounter with a planet. When the meteoroids pass by Earth, some are accelerated (making wider orbits around the Sun), others are decelerated (making shorter orbits), resulting in gaps in the dust trail in the next return (like opening a curtain, with grains piling up at the beginning and end of the gap). Also, Jupiter's perturbation can dramatically change sections of

740-445: A small boulder. Dust mote sized solids are orders of magnitude more common than those the size of sand grains, which, in turn, are similarly more common than those the size of pebbles, and so on. When the ice warms and sublimates, the vapor can drag along dust, sand, and pebbles. Each time a comet swings by the Sun in its orbit , some of its ice vaporizes, and a certain number of meteoroids will be shed. The meteoroids spread out along

814-467: A time relative to seasons, since this determines the contribution of the elliptical orbit to seasonal variations. The variation of the seasons is primarily controlled by the annual cycle of the elevation angle of the Sun, which is a result of the tilt of the axis of the Earth measured from the plane of the ecliptic . The Earth's eccentricity and other orbital elements are not constant, but vary slowly due to

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888-435: Is 236 years early, less accurately shows Eris coming to perihelion in 2260. 4 Vesta came to perihelion on 26 December 2021, but using a two-body solution at an epoch of July 2021 less accurately shows Vesta came to perihelion on 25 December 2021. Trans-Neptunian objects discovered when 80+ AU from the Sun need dozens of observations over multiple years to well constrain their orbits because they move very slowly against

962-399: Is lowest. Despite this, summers in the northern hemisphere are on average 2.3 °C (4 °F) warmer than in the southern hemisphere, because the northern hemisphere contains larger land masses, which are easier to heat than the seas. Perihelion and aphelion do however have an indirect effect on the seasons: because Earth's orbital speed is minimum at aphelion and maximum at perihelion,

1036-464: Is the Perseids , which peak on 12 August of each year at over one meteor per minute. NASA has a tool to calculate how many meteors per hour are visible from one's observing location. The Leonid meteor shower peaks around 17 November of each year. The Leonid shower produces a meteor storm, peaking at rates of thousands of meteors per hour. Leonid storms gave birth to the term meteor shower when it

1110-495: The "line of nodes" where a planet's tilted orbit intersects the plane of reference; here they may be 'seen' as the points where the blue section of an orbit meets the pink. The chart shows the extreme range—from the closest approach (perihelion) to farthest point (aphelion)—of several orbiting celestial bodies of the Solar System : the planets, the known dwarf planets, including Ceres , and Halley's Comet . The length of

1184-505: The Institut de Mécanique Céleste et de Calcul des Éphémérides (IMCCE). Because meteor shower particles are all traveling in parallel paths and at the same velocity, they will appear to an observer below to radiate away from a single point in the sky. This radiant point is caused by the effect of perspective , similar to parallel railroad tracks converging at a single vanishing point on the horizon. Meteor showers are normally named after

1258-402: The inner planets, situated outward from the Sun as Mercury, Venus, Earth, and Mars. The reference Earth-orbit is colored yellow and represents the orbital plane of reference . At the time of vernal equinox, the Earth is at the bottom of the figure. The second image (below-right) shows the outer planets, being Jupiter, Saturn, Uranus, and Neptune. The orbital nodes are the two end points of

1332-428: The precession of the axes .) The dates and times of the perihelions and aphelions for several past and future years are listed in the following table: The following table shows the distances of the planets and dwarf planets from the Sun at their perihelion and aphelion. These formulae characterize the pericenter and apocenter of an orbit: While, in accordance with Kepler's laws of planetary motion (based on

1406-458: The 1995 Alpha Monocerotids outburst from dust trails. In anticipation of the 1999 Leonid storm, Robert H. McNaught , David Asher , and Finland's Esko Lyytinen were the first to apply this method in the West. In 2006 Jenniskens published predictions for future dust trail encounters covering the next 50 years. Jérémie Vaubaillon continues to update predictions based on observations each year for

1480-422: The 1995 alpha Monocerotids , and from earlier not widely known identifications of past Earth storms. Over more extended periods, the dust trails can evolve in complicated ways. For example, the orbits of some repeating comets, and meteoroids leaving them, are in resonant orbits with Jupiter or one of the other large planets – so many revolutions of one will equal another number of the other. This creates

1554-461: The Earth reaches aphelion currently in early July, approximately 14 days after the June solstice . The aphelion distance between the Earth's and Sun's centers is currently about 1.016 71  AU or 152,097,700 km (94,509,100 mi). The dates of perihelion and aphelion change over time due to precession and other orbital factors, which follow cyclical patterns known as Milankovitch cycles . In

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1628-401: The Earth, Moon and Sun systems are the unique suffixes commonly used. Exoplanet studies commonly use -astron , but typically, for other host systems the generic suffix, -apsis , is used instead. The perihelion (q) and aphelion (Q) are the nearest and farthest points respectively of a body's direct orbit around the Sun . Comparing osculating elements at a specific epoch to those at

1702-538: The Earth, Sun, stars, and the Galactic Center respectively. The suffix -jove is occasionally used for Jupiter, but -saturnium has very rarely been used in the last 50 years for Saturn. The -gee form is also used as a generic closest-approach-to "any planet" term—instead of applying it only to Earth. During the Apollo program , the terms pericynthion and apocynthion were used when referring to orbiting

1776-570: The International Astronomical Union's list of meteor showers. Any other Solar System body with a reasonably transparent atmosphere can also have meteor showers. As the Moon is in the neighborhood of Earth it can experience the same showers, but will have its own phenomena due to its lack of an atmosphere per se , such as vastly increasing its sodium tail . NASA now maintains an ongoing database of observed impacts on

1850-556: The Moon ; they reference Cynthia, an alternative name for the Greek Moon goddess Artemis . More recently, during the Artemis program , the terms perilune and apolune have been used. Regarding black holes, the term peribothron was first used in a 1976 paper by J. Frank and M. J. Rees, who credit W. R. Stoeger for suggesting creating a term using the greek word for pit: "bothron". The terms perimelasma and apomelasma (from

1924-589: The Perseids, which they believe are creatures that look like purses. At the end of the episode, Allie's grandfather Mr. Renkins says that the Perseids is a meteor shower happening in early August. John Denver 's song "Rocky Mountain High" references the showers with the lyric, "I've seen it raining fire in the sky." Meteor shower A meteor shower in August 1583 was recorded in the Timbuktu manuscripts . In

1998-463: The Sun is 0.7 million km, and the radius of Jupiter (the largest planet) is 0.07 million km, both too small to resolve on this image. Currently, the Earth reaches perihelion in early January, approximately 14 days after the December solstice . At perihelion, the Earth's center is about 0.983 29 astronomical units (AU) or 147,098,070 km (91,402,500 mi) from the Sun's center. In contrast,

2072-489: The Sun ;– while more massive objects (responsible for bolides or fireballs ) will tend to be affected less by radiation pressure. This makes some dust trail encounters rich in bright meteors, others rich in faint meteors. Over time, these effects disperse the meteoroids and create a broader stream. The meteors we see from these streams are part of annual showers , because Earth encounters those streams every year at much

2146-425: The actual closest approach between the Sun's and the Earth's centers (which in turn defines the timing of perihelion in a given year). Because of the increased distance at aphelion, only 93.55% of the radiation from the Sun falls on a given area of Earth's surface as does at perihelion, but this does not account for the seasons , which result instead from the tilt of Earth's axis of 23.4° away from perpendicular to

2220-570: The anticipated Leonid shower return of 1898 and 1899. Meteor storms were expected, but the final calculations showed that most of the dust would be far inside Earth's orbit. The same results were independently arrived at by Adolf Berberich of the Königliches Astronomisches Rechen Institut (Royal Astronomical Computation Institute) in Berlin, Germany. Although the absence of meteor storms that season confirmed

2294-492: The atmosphere while at heights above 80 kilometres (50 mi). Some Catholics refer to the Perseids as the "tears of Saint Lawrence ", suspended in the sky but returning to Earth once a year on August 10, the canonical date of that saint's martyrdom in 258 AD. The saint is said to have been burned alive on a gridiron. His manner of death is almost certainly the origin of the Mediterranean folk legend claiming that

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2368-663: The calculations, the advance of much better computing tools was needed to arrive at reliable predictions. In 1981, Donald K. Yeomans of the Jet Propulsion Laboratory reviewed the history of meteor showers for the Leonids and the history of the dynamic orbit of Comet Tempel-Tuttle. A graph from it was adapted and re-published in Sky and Telescope . It showed relative positions of the Earth and Tempel-Tuttle and marks where Earth encountered dense dust. This showed that

2442-561: The comet, Milos Plavec was the first to offer the idea of a dust trail , when he calculated how meteoroids, once freed from the comet, would drift mostly in front of or behind the comet after completing one orbit. The effect is simple celestial mechanics  – the material drifts only a little laterally away from the comet while drifting ahead or behind the comet because some particles make a wider orbit than others. These dust trails are sometimes observed in comet images taken at mid infrared wavelengths (heat radiation), where dust particles from

2516-422: The conservation of angular momentum ) and the conservation of energy, these two quantities are constant for a given orbit: where: Note that for conversion from heights above the surface to distances between an orbit and its primary, the radius of the central body has to be added, and conversely. The arithmetic mean of the two limiting distances is the length of the semi-major axis a . The geometric mean of

2590-501: The constellation from which the meteors appear to originate. This "fixed point" slowly moves across the sky during the night due to the Earth turning on its axis, the same reason the stars appear to slowly march across the sky. The radiant also moves slightly from night to night against the background stars (radiant drift) due to the Earth moving in its orbit around the Sun. See IMO Meteor Shower Calendar 2017 ( International Meteor Organization ) for maps of drifting "fixed points." When

2664-526: The distance measured between the barycenter of the 2-body system and the center of mass of the orbiting body. However, in the case of a spacecraft , the terms are commonly used to refer to the orbital altitude of the spacecraft above the surface of the central body (assuming a constant, standard reference radius). The words "pericenter" and "apocenter" are often seen, although periapsis/apoapsis are preferred in technical usage. The words perihelion and aphelion were coined by Johannes Kepler to describe

2738-401: The dust trail, especially for a short period comets, when the grains approach the giant planet at their furthest point along the orbit around the Sun, moving most slowly. As a result, the trail has a clumping , a braiding or a tangling of crescents , of each release of material. The third effect is that of radiation pressure which will push less massive particles into orbits further from

2812-436: The entire trajectory of the comet to form a meteoroid stream, also known as a "dust trail" (as opposed to a comet's "gas tail" caused by the tiny particles that are quickly blown away by solar radiation pressure). Recently, Peter Jenniskens has argued that most of our short-period meteor showers are not from the normal water vapor drag of active comets, but the product of infrequent disintegrations, when large chunks break off

2886-652: The event most accurately. After spending the last weeks of 1833 collecting information, he presented his findings in January 1834 to the American Journal of Science and Arts , published in January–April 1834, and January 1836. He noted the shower was of short duration and was not seen in Europe , and that the meteors radiated from a point in the constellation of Leo . He speculated the meteors had originated from

2960-483: The horizontal bars correspond to the extreme range of the orbit of the indicated body around the Sun. These extreme distances (between perihelion and aphelion) are the lines of apsides of the orbits of various objects around a host body. Distances of selected bodies of the Solar System from the Sun. The left and right edges of each bar correspond to the perihelion and aphelion of the body, respectively, hence long bars denote high orbital eccentricity . The radius of

3034-402: The host Earth . Earth's two apsides are the farthest point, aphelion , and the nearest point, perihelion , of its orbit around the host Sun. The terms aphelion and perihelion apply in the same way to the orbits of Jupiter and the other planets , the comets , and the asteroids of the Solar System . There are two apsides in any elliptic orbit . The name for each apsis is created from

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3108-643: The link between meteor showers and comets. The finding is contained in an exchange of letters with Angelo Secchi . In his 2006 novel Against the Day , American novelist Thomas Pynchon refers to the Perseid meteor shower being watched by three characters west of the Dolores Valley after playing a game of tarot . In the TV series Curious George , season 7 episode 1b, George and his friends Allie and Bill hunt for

3182-427: The meteoroids are mostly behind and outside the path of the comet, but paths of the Earth through the cloud of particles resulting in powerful storms were very near paths of nearly no activity. In 1985, E. D. Kondrat'eva and E. A. Reznikov of Kazan State University first correctly identified the years when dust was released which was responsible for several past Leonid meteor storms. In 1995, Peter Jenniskens predicted

3256-466: The meteoroids due to increased distance from the sun should marginally decrease meteor brightness. This is somewhat balanced because the slower descent means that Martian meteors have more time to ablate. On March 7, 2004, the panoramic camera on Mars Exploration Rover Spirit recorded a streak which is now believed to have been caused by a meteor from a Martian meteor shower associated with comet 114P/Wiseman-Skiff . A strong display from this shower

3330-517: The modern era, the first great meteor storm was the Leonids of November 1833. One estimate is a peak rate of over one hundred thousand meteors an hour, but another, done as the storm abated, estimated more than two hundred thousand meteors during the 9 hours of the storm, over the entire region of North America east of the Rocky Mountains . American Denison Olmsted (1791–1859) explained

3404-519: The moon maintained by the Marshall Space Flight Center whether from a shower or not. Many planets and moons have impact craters dating back large spans of time. But new craters, perhaps even related to meteor showers are possible. Mars, and thus its moons, is known to have meteor showers. These have not been observed on other planets as yet but may be presumed to exist. For Mars in particular, although these are different from

3478-444: The moving radiant is at the highest point, it will reach the observer's sky that night. The Sun will be just clearing the eastern horizon. For this reason, the best viewing time for a meteor shower is generally slightly before dawn — a compromise between the maximum number of meteors available for viewing and the brightening sky, which makes them harder to see. Meteor showers are named after the nearest constellation, or bright star with

3552-548: The objects in the Solar System with an atmosphere: Mercury, Venus, Saturn's moon Titan , Neptune's moon Triton , and Pluto . Perihelion An apsis (from Ancient Greek ἁψίς ( hapsís )  'arch, vault'; pl.   apsides / ˈ æ p s ɪ ˌ d iː z / AP -sih-deez ) is the farthest or nearest point in the orbit of a planetary body about its primary body . The line of apsides (also called apse line, or major axis of

3626-401: The ones seen on Earth because of the different orbits of Mars and Earth relative to the orbits of comets. The Martian atmosphere has less than one percent of the density of Earth's at ground level, at their upper edges, where meteoroids strike; the two are more similar. Because of the similar air pressure at altitudes for meteors, the effects are much the same. Only the relatively slower motion of

3700-402: The orbit) is the line connecting the two extreme values . Apsides pertaining to orbits around the Sun have distinct names to differentiate themselves from other apsides; these names are aphelion for the farthest and perihelion for the nearest point in the solar orbit. The Moon 's two apsides are the farthest point, apogee , and the nearest point, perigee , of its orbit around

3774-467: The orbital motions of the planets around the Sun. The words are formed from the prefixes peri- (Greek: περί , near) and apo- (Greek: ἀπό , away from), affixed to the Greek word for the Sun, ( ἥλιος , or hēlíos ). Various related terms are used for other celestial objects . The suffixes -gee , -helion , -astron and -galacticon are frequently used in the astronomical literature when referring to

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3848-429: The orbiting body when the latter is located: 1) at the periapsis point, or 2) at the apoapsis point (compare both graphics, second figure). The line of apsides denotes the distance of the line that joins the nearest and farthest points across an orbit; it also refers simply to the extreme range of an object orbiting a host body (see top figure; see third figure). In orbital mechanics , the apsides technically refer to

3922-470: The particular location of the stream. During the peak, the rate of meteors reaches 60 or more per hour. They can be seen all across the sky; however, because of the shower's radiant in the constellation of Perseus, the Perseids are primarily visible in the Northern Hemisphere . As with many meteor showers the visible rate is greatest in the pre-dawn hours, since more meteoroids are scooped up by

3996-588: The perihelion passage. For example, using an epoch of 1996, Comet Hale–Bopp shows perihelion on 1 April 1997. Using an epoch of 2008 shows a less accurate perihelion date of 30 March 1997. Short-period comets can be even more sensitive to the epoch selected. Using an epoch of 2005 shows 101P/Chernykh coming to perihelion on 25 December 2005, but using an epoch of 2012 produces a less accurate unperturbed perihelion date of 20 January 2006. Numerical integration shows dwarf planet Eris will come to perihelion around December 2257. Using an epoch of 2021, which

4070-409: The perturbing effects of the planets and other objects in the solar system (Milankovitch cycles). On a very long time scale, the dates of the perihelion and of the aphelion progress through the seasons, and they make one complete cycle in 22,000 to 26,000 years. There is a corresponding movement of the position of the stars as seen from Earth, called the apsidal precession . (This is closely related to

4144-409: The plane of Earth's orbit. Indeed, at both perihelion and aphelion it is summer in one hemisphere while it is winter in the other one. Winter falls on the hemisphere where sunlight strikes least directly, and summer falls where sunlight strikes most directly, regardless of the Earth's distance from the Sun. In the northern hemisphere, summer occurs at the same time as aphelion, when solar radiation

4218-488: The planet takes longer to orbit from June solstice to September equinox than it does from December solstice to March equinox. Therefore, summer in the northern hemisphere lasts slightly longer (93 days) than summer in the southern hemisphere (89 days). Astronomers commonly express the timing of perihelion relative to the First Point of Aries not in terms of days and hours, but rather as an angle of orbital displacement,

4292-411: The planets of the Solar System as seen from above the northern pole of Earth's ecliptic plane , which is coplanar with Earth's orbital plane . The planets travel counterclockwise around the Sun and for each planet, the blue part of their orbit travels north of the ecliptic plane, the pink part travels south, and dots mark perihelion (green) and aphelion (orange). The first image (below-left) features

4366-496: The prefixes ap- , apo- (from ἀπ(ό) , (ap(o)-)  'away from') for the farthest or peri- (from περί (peri-)  'near') for the closest point to the primary body , with a suffix that describes the primary body. The suffix for Earth is -gee , so the apsides' names are apogee and perigee . For the Sun, the suffix is -helion , so the names are aphelion and perihelion . According to Newton's laws of motion , all periodic orbits are ellipses. The barycenter of

4440-415: The previous return to the Sun are spread along the orbit of the comet (see figures). The gravitational pull of the planets determines where the dust trail would pass by Earth orbit, much like a gardener directing a hose to water a distant plant. Most years, those trails would miss the Earth altogether, but in some years, the Earth is showered by meteors. This effect was first demonstrated from observations of

4514-412: The relation between meteors and comets in his work "Notes upon the astronomical theory of the falling stars" ( 1867 ). In the 1890s, Irish astronomer George Johnstone Stoney (1826–1911) and British astronomer Arthur Matthew Weld Downing (1850–1917) were the first to attempt to calculate the position of the dust at Earth's orbit. They studied the dust ejected in 1866 by comet 55P/Tempel-Tuttle before

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4588-411: The same period, phallic processions and other sexual rites were common. Christianity, which had a different relationship with sexuality and generativity compared to Greco-Roman culture , replaced this sexual connotation with a reference to martyrdom. In 1836 Adolphe Quetelet wrote: J'ai cru remarquer aussi une fréquence plus grande de ces météores au mois d'août (du 8 au 15) "I think I noticed also

4662-414: The same rate. When the meteoroids collide with other meteoroids in the zodiacal cloud , they lose their stream association and become part of the "sporadic meteors" background. Long since dispersed from any stream or trail, they form isolated meteors, not a part of any shower. These random meteors will not appear to come from the radiant of the leading shower. In most years, the most visible meteor shower

4736-455: The shooting stars are the sparks of Saint Lawrence's martyrdom . The legend holds that during the night of August 9 to 10, cooled embers appear in the ground under plants; these embers are known as the "coal of Saint Lawrence." The transition in favor of the Catholic saint and his feast day on August 10, moving away from pagan gods and their festivals — a process known as Christianization —

4810-508: The short term, such dates can vary up to 2 days from one year to another. This significant variation is due to the presence of the Moon: while the Earth–Moon barycenter is moving on a stable orbit around the Sun, the position of the Earth's center which is on average about 4,700 kilometres (2,900 mi) from the barycenter, could be shifted in any direction from it—and this affects the timing of

4884-406: The side of the Earth moving forward into the stream, corresponding to local times between midnight and noon, as can be seen in the accompanying diagram. While many meteors arrive between dawn and noon, they are usually not visible due to daylight. Some can also be seen before midnight, often grazing the Earth's atmosphere to produce long bright trails and sometimes fireballs. Most Perseids burn up in

4958-405: The so-called longitude of the periapsis (also called longitude of the pericenter). For the orbit of the Earth, this is called the longitude of perihelion , and in 2000 it was about 282.895°; by 2010, this had advanced by a small fraction of a degree to about 283.067°, i.e. a mean increase of 62" per year. For the orbit of the Earth around the Sun, the time of apsis is often expressed in terms of

5032-453: The sons of Perseus in Greek mythology . The stream of debris is called the Perseid cloud and stretches along the orbit of the comet Swift–Tuttle . The cloud consists of particles ejected by the comet as it travels on its 133-year orbit. Most of the particles have been part of the cloud for around a thousand years. However, there is also a relatively young filament of dust in the stream that

5106-405: The two bodies may lie well within the bigger body—e.g., the Earth–Moon barycenter is about 75% of the way from Earth's center to its surface. If, compared to the larger mass, the smaller mass is negligible (e.g., for satellites), then the orbital parameters are independent of the smaller mass. When used as a suffix—that is, -apsis —the term can refer to the two distances from the primary body to

5180-491: The two distances is the length of the semi-minor axis b . The geometric mean of the two limiting speeds is which is the speed of a body in a circular orbit whose radius is a {\displaystyle a} . Orbital elements such as the time of perihelion passage are defined at the epoch chosen using an unperturbed two-body solution that does not account for the n-body problem . To get an accurate time of perihelion passage you need to use an epoch close to

5254-606: Was expected on December 20, 2007. Other showers speculated about are a "Lambda Geminid" shower associated with the Eta Aquariids of Earth ( i.e. , both associated with Comet 1P/Halley ), a "Beta Canis Major" shower associated with Comet 13P/Olbers , and "Draconids" from 5335 Damocles . Isolated massive impacts have been observed at Jupiter: The 1994 Comet Shoemaker–Levy 9 which formed a brief trail as well, and successive events since then (see List of Jupiter events .) Meteors or meteor showers have been discussed for most of

5328-485: Was facilitated by the phonetic assonance of the Latin name Laurentius with Acca Larentia , a goddess previously celebrated during the summer period alongside Priapus , as a fertility deity. Among the Romans, it was believed that the trails of the Perseids represented the benevolent rain of Priapus' seed . In this context, the god's cosmogonic phallus acted as a life-giver, blessing the fields and promoting fertility. During

5402-596: Was first realised that, during the November 1833 storm, the meteors radiated from near the star Gamma Leonis. The last Leonid storms were in 1999, 2001 (two), and 2002 (two). Before that, there were storms in 1767, 1799, 1833, 1866, 1867, and 1966. When the Leonid shower is not storming , it is less active than the Perseids. See the Infographics on Meteor Shower Calendar-2021 on the right. Official names are given in

5476-439: Was pulled off the comet in 1865, which can give an early mini-peak the day before the maximum shower. The dimensions of the cloud in the vicinity of the Earth are estimated to be approximately 0.1 astronomical units (AU) across and 0.8 AU along the Earth's orbit, spread out by annual interactions with the Earth's gravity. The shower is visible from mid-July each year, with the peak in activity between 9 and 14 August, depending on

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