Comet Enke (2P/Encke) is allcometIt is the comet with the shortest length, weak brightness and low cohesion, generally does not produce comet tails, and has the most occurrences.
It was first discovered on January 17, 1786, and was not discovered until November 26, 1818FranceastronomerEncke It took six weeks to calculate the orbit of this comet, with a period of 3.3 years, and predicted that it would return on May 24, 1822PerihelionHe came back on time, ChengjiHalley's CometAfter that, the second one returned as predictedcometPeople call it "Comet Enke".
Comet Enke is not big. At its brightest, it is only a fifth class star. Most of the time, it has noCometary tail, just a vague cloud.It has returned 57 times since its discovery, and is the most frequent one to return to her parents' home.The orbit of this comet is getting smaller and smaller. Every time it returns, its cycle will be shortened by 3 hours. Some people estimate that one day it will fall into the sun or break up on its own.
Comet Enke
Shortest cyclecometIs also the second comet to return as predicted.1818 byFranceJ50. Ponce found that,GermanyJF. Enke first figured out itstrack, which is named after forecasting its next return.Its "perihelion distance" and "telehelion distance" are 0.3380 and 4.0937 respectivelyAstronomical unit, cycle 3. 1984,Eccentricity0.8474。Comet Enke is a small comet. When it was discovered in 1818, its brightness was only 5. Today, it can not be observed with the naked eye, and generally no longer existsCometary tailIt is only a small cloud like spot that is not very bright in the telescope.Comet Enke has obvious acceleration, and almost every return will be 0.10-0.13 days ahead of schedule, so some people predict that it will fall intosunlightHowever, some people think that its true brightness has not changed significantly in the past hundred years, and the acceleration phenomenon has also eased, which may still exist for some time.
And it is recognized thatSouth Taurids The mother comet of.[1]
German astronomer.Born on September 23, 1791hamburger；On August 26, 1865, he died in Spandau (near Berlin).
Enke entered in 1811University of Gottingen, become a mathematicianGaussianHe was one of the students of the Berlin Observatory in 1825.
Once inNapoleonic Wars In the end, he became an artillery officer.After returning to China, he continued to study astronomy and calculated the orbit of a comet in 1819. He proved that the period of this comet was only three and a third years.Since then, this comet has become the second comet predicted to return, and the first comet isHalley's Comet。Comet Enke is the first one discoveredShort period cometNo comet with a shorter period has been found.
In 1835, Comet Enke leftMercuryThis is the first time that people have measured thisplanetThe chance of mass is determined according to the influence of its gravity on the orbit of the comet.
Enke's old age (using the pastVenus transitCalculated the distance of the sun: 95300000 miles.This figure is 2% higher, but it is the most accurate value obtained at that time.
French astronomer (1761-1831), born in Peyre, was poor from childhood and only received basic education.
In 1789, heMarcelOur observatory is responsible for guarding the observatory and carrying out astronomical work according to the instructions of observers.Because of his diligence and intelligence, Ponce was soon allowed to use his own instruments for observation.He was rightfixed starThe distribution of is superior to human memory, so slight changes within the observation range can be detected.
In 1801, Ponce began his career of searching for new comets. Until 1827, he found a new comet almost every other year.In 1813, Ponce was promoted to assistant astronomer and became assistant director five years later.In the same year, he was awarded the "Lalande Prize" by the Paris Academy of Sciences for discovering three comets.Ponce suspected that one of the three comets he had discovered had been discovered by J.F. Encke in 1805, and he put forward his idea to Enke.Enke therefore started to calculate the comet's orbital data and found that its period was 3.3 years, and also estimated that the comet would return in 1822.As a result, K. RuemkerAustraliaSee the expected comet.This comet was named "Encke Comet";But Enke himself often called it "Comet Pons 」。
There are 37 comets that Ponce discovered or participated in discovering in his life.In 1827, Ponce's eyesight began to decline, and four years later, he completely stopped his observation work.In October 1831, PonceFlorenceDeath.To commemorate Ponce, astronomersMoonOne onCraterNamed after him.[2]
Discovery process
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SubsequentHarleyLater, German astronomer Enke predicted the return of another comet in 1818.The discovery of this comet also has a tortuous story.
On January 17, 1786, French astronomer Marchionne, using a small telescope in Paris, found thatAquariusβThere is a small comet near the star, its brightness is about 5, and there is no tail.The next day, he told the storymessier , prepare to observe together.But for several days in a row, the weather was not good, and the comet had been hiding in the thick clouds without showing up.
On November 7, 1795,UranusDiscovererbritainastronomerWilliam Herschel 's sisterCaroline Herschel stayLondonIn a small town in the westscorpioA comet of 5.5 grade with invisible tail was found.German astronomerAubersThe comet was also seen on November 21, but it was too dark to calculate the exact orbit from its position.
On October 19, 1805, Suris of France found a barely usednaked eyeVisible comets.The next morning, in GermanyFrankfurtThe comet was also discovered.Ten days later, this comet has grown a small tail.It reached the brightness of - 4 on November 20.
On November 26, 1818, Ponce, an old guard at the Marseille Observatory in France, saw a small comet as bright as an eighth class star (he observed 37 comets from 1801 to 1827) with years of experience in observing the sky and recognizing stars and his keen eyesight, and made a report to the Observatory.
Comet Enke
In January 1819, German astronomer Enke began to track and observe the comet.He used his teacherGaussianAn ingenious method proposed previously to determine the orbit of celestial bodies based on three complete observations, and it is calculated that the orbit of this comet is not too flat and longellipseThe period of the comet in this orbit is only 3 years and 106 days.This comet is the same as the comet observed by Meishang in 1786, Caroline Herschel in 1795, and Surius et al. in 1805.He also noticed that since 1786, this comet has missed the net seven times.Enke predicted that the date when the comet next passed the perihelion was May 24, 1822.In 1822, like a punctual train, the comet passed the perihelion of the orbit on the day predicted by Enke.Enke succeeded, so the comet was namedComet Enke。
Operation characteristics
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Observation site
Comet Enke orbits the sun 3 times every 10 years, but people on the ground cannot see it every timeNorthern HemisphereAppear, then, next time onlyLow latitude areaTo see it, and the other best observation place issouthern hemisphere。
Cycle shortening
Comet Enke has the shortest period among the comets. Its perihelion is only 50 million kilometers away from the sun, and its aphelion is more than 100 million kilometers closer than Jupiter.Enke proved that its orbital motion is accelerating, and each regression cycle is shortened by about 3 hours.But the return period in 1868 was only shortened by more than one hour.This sudden change took place several times later.Because this special movement has not been found in other cometsLitterateurFeel puzzled.
Time of existence
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Comet Enke
According to the small distant distance of comet Enke, it may have existed for thousands of years.In addition, judging from its appearance, it has no hair or tail, and is already an old dog.In April 1984Space probeIt was found that Comet Enke, located between the Earth and Venus at that time, was emitting a large amount of water vapor, and the rate of water loss was three times higher than the original estimate.It is generally estimated by the scientific community that the life of Comet Enke is not long, and it will probably disappear in this century.However, other astronomers do not think so. They say that although the apparent brightness of Comet Enke has been darkening, its "true" brightness has not changed significantly in the past 100 years.Moreover, it has thrown out no less material in recent returns, and there is no sign of "oil drying lamp off".
Enke also found that the period of the comet will decrease by about 2.5 hours per revolution, and pointed out that,JupiterAlthough it can strongly affect the orbit of this comet, onlyplanetThe perturbation of can not explain this effect.The period of Comet Enke continues to shorten, but the rate of shortening is slowing down;The reason for the slowdown is not yet clear.
Return in 2007
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Comet Enke passed on April 19, 2007PerihelionAt the same time, its brightness also rapidly increased to about 4Atmospheric tranquilityFor public use in the suburbs of Gaonaked eyeIt is possible to see its "beautiful shadow".But because it is too close to the sun, the time suitable for observation is only a few days.On April 20, the comet was about 17 ° away from the sun, and we couldAriesFind it.In the next few days, the angular distance between the comet and the sun will gradually decrease, and the observation conditions will become worse and worseSolar timeHas become the observation target of the southern hemisphere.[3]
Related reports
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According to the astronomical forecast released by the Zijinshan Observatory of the Chinese Academy of Sciences, Comet Enke, which has been away from the earth for three years, will return to people's sight this Thursday. On Friday, Venus will romantically date the moon in the southwest sky.As the weekend approaches, astronomy enthusiasts must not miss this bustling astronomical "party".
Among periodic comets, Comet Enke is the most attached to the Earth, returning every 3.3 years.This time, Comet Enke reached the perihelion on Thursday and brightened rapidly. The public may see the comet with the naked eye in the suburbs with high atmospheric transparency.However, because it is too close to the sun, the time suitable for observation is only a few days. On Thursday and Friday, we can find it in the western low altitude Aries after sunset.
At about 16:00 on Friday, the crescent moon will appear with the bright Venus, and a wonderful scene of "Venus conjunct the moon" will be staged in broad daylight.Looking at the southwest sky, Venus is in the southwest corner below the moon hook, shining against each other until dusk after sunset.If the weather is fine, citizens can see it with the naked eye.
[4]
China News Network, Nanjing, October 3, by wire (Zhang Yang and Zhu Xiaoying)Zijinshan Observatory, Chinese Academy of SciencesOn the 3rd, the important astronomical phenomena in October were announced.In the October sky of the "golden nine and silver ten", the "Venus conjunct the moon", the Orion meteor shower, the "return" of Comet 2P Enke and Comet 103P Hartley 2 will take turns to "stage" the sky and light up the night sky.
The "Venus conjunct moon" on October 9 may be the last time that the public observed it in the evening.Since then, Venus will gradually approach the sun, and it will be more and more difficult to see it.
In addition to "Venus conjoins the moon", Mars will also conjoin with the moon on October 10, but because Mars is far less bright than Venus, it is difficult to find it in the southwest low sky at dusk.
On October 20, "Jupiter conjunct the moon" appeared. In the early morning of October 21, the public will welcomeHalley's CometOrion meteor shower, one of the meteor showers.It should not be a problem to see more than 30 meteors within one hour before dawn.
The active period of Orion meteor shower is from October 2 to November 7 every year, which overlaps with many meteor showers, such as the Taurus meteor shower in the north and south, and the Gemini ε meteor shower. Therefore, the public can observe several meteor showers at the same time.
On October 28, Comet 2P Enke and Comet 103P Hartley 2 "returned" and passed the perihelion.
The cycle of Comet 2P Enke is 3.3 years, while the well-known Comet Halley "returns" once in 76 years.
Comet 103P Hartley 2 is aShort period cometThe comet orbits the earth once every 6.47 years. It was discovered by Hartley in 1986. Since then, the orbit of the comet has been changed twice due to the influence of Jupiter's huge gravity.At the beginning of August, it is located in the Pegasus sky region, and will enter Perseus in October after passing Scorpio and Cassiopeia.On October 21, the comet will pass near the site, about 18 million kilometers away from us.After the perihelion on October 28, the brightness is expected to reach 4.6, which is visible to the naked eye and takes a long time to observe.[5]
Comet Enke with three tails
How can a comet drag three tails?Under normal circumstances, a comet will have two comets: the ion tail formed by charged particles released by the comet under the action of the solar wind, and the dust tail formed by small debris scattered on the orbit behind the comet.In many cases, comets seem to have only one tail, because it is not easy to see another tail on the earth.But in this image, Comet Enke appears to have three tails, because its ion tail split shortly before taking the picture.The complex solar wind occasionally produces turbulence, which results in some unusual structures on the ion tail, and even breaks the ion tail in very few cases.In another picture taken two days later, this comet looks much more normal[6]。
