Halley's Comet

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1P / Halley [i]
Lspn comet halley.jpg
Halley's Comet on March 8, 1986 (W. Liller)
Properties of the orbit ( animation )
Orbit type short-term
Numerical eccentricity 0.967
Perihelion 0.586 AU
Aphelion 35,082 AU
Major semi-axis 17.834 AU
Sidereal period 75.32 a
Inclination of the orbit plane 162.262 °
Perihelion February 9, 1986 at 6:40 UTC
Orbital velocity in the perihelion 54.57 km / s
Physical properties of the core
Medium diameter 15.3 × 7.2 × 7.2 km
Dimensions 2 · 10 14 kg
Medium density 0.55 g / cm³
Albedo 0.05
history
Explorer First sightings probably prehistoric; Periodicity recognized by Halley (1705); first targeted rediscovery by Palitzsch (1758).
Date of discovery Prehistoric
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

The Comet Halley , and Halley's Comet and officially 1P / Halley called, is one of the most famous long comet .

It is very bright and returns on average every 75.3 years. He last came near the earth in 1986; its next return was calculated for 2061.

properties

Orbit

Halley's Comet is a periodic comet that returns every 74 to 79 years. He is the only one who could mostly be observed with the naked eye .

"Halley" has a very elongated elliptical orbit, which extends from the point closest to the sun ( perihelion ) with 0.586  AU between the orbits of the planets Mercury and Venus to the point furthest from the sun ( aphelion ) with 35.082 AU in the area of ​​the Neptune orbit . The inclination of its orbit against the ecliptic is 162.262 °.

The orbit time varies because the orbit is influenced by the gravity of other bodies, especially Jupiter . Between 1835 and 1910 it was less than 75 years and between 1222 and 1301 it was 79 years.

Perihelion

May 25, 240 BC Chr.
13 October 164 v. Chr.
06 Aug. 87 v. Chr.
11 Oct. 12 v. Chr.
26 January 66
March 22 141
18 May 218
20 April 295
16 February 374
28 June 451
27 September 530

March 15, 607
0October 3, 684
May 21, 760
February 28, 837
July 19, 912
0September 6, 989
March 21, 1066
April 19, 1145
September 29, 1222
October 26, 1301
November 11, 1378

June 10, 1456
August 26, 1531
October 27, 1607
September 15, 1682
March 13, 1759
November 16, 1835
April 20, 1910
0February 9, 1986
July 28, 2061 (forecast)

The comet nucleus

In the pictures of the Giotto space probe, the core of the comet can be seen as an irregularly shaped structure with dimensions of around 15.3 km × 7.2 km × 7.2 km. The volume was determined to be around 420 cubic kilometers and the density to an astonishingly low value of 0.55 ± 0.25 g / cm³. The surface of the core is very dark ( albedo 0.05) and slightly reddish (similar to a P-type asteroid ). The nucleus rotates around its longitudinal axis with a period of 7.1 days. Its precession axis is inclined by 66 ° to the longitudinal axis. The precession period is only 3.7 days, which is shorter than its rotation period, which is unusual. The images also showed that a large part of the surface is inactive: gas and dust in the form of jets were hurled into space from only a few demarcated regions on the side of the core facing the sun . Giotto also measured the composition of this material: water (80% by volume ) and carbon monoxide (10%) dominate, but methane , ammonia and other hydrocarbons were also found. Only minor traces of cyan occurred.

Research in recent years has shown that long-period comets and those planetoids that orbit the sun outside of Jupiter have a lot in common in terms of structure, color, density and orbital dynamics. Perhaps Halley's Comet was such a trans-Neptunian object 3,000 to 10,000 years ago .

Constant loss of matter

Comets are often clearly visible near the earth or the sun, but lose their brightness over the centuries if they have short orbital times . This is related to the release of gases and dust from the comet's core when the sun's rays are more intense . The material that is subsequently responsible for the formation of the coma and the tail is "blown away" by the solar wind and is thus irretrievably lost to the comet. For the Halley comet, loss rates of more than 50 tons per second were determined in the vicinity of the sun - the total loss of material during the last approach to the sun in 1986 was 500 million tons (5 * 10 11  kg), i.e. H. 0.25% of its total mass.

In its “historical” time, Halley's comet lost a noticeable part of its material with every approach to the sun. For several centuries, its “reputation” as a particularly bright comet has not been entirely justified. Since its last return, there have been some newly discovered, long-period or non-periodic comets that clearly surpassed "Halley" in luminosity, for example comet Hale-Bopp in 1997. However, Halley's comet is still the brightest of the short-period comets .

Remnants of Halley's Comet are also responsible for two meteor streams , namely the Orionids , which appear in large numbers in October of each year, and the Eta-Aquariids in May. These granules, weighing only a few milligrams, have spread over the course of time along the entire orbit of the comet; when the earth crosses this orbit, thousands of these grains burn up in their atmosphere every day as meteors or "falling stars". Both meteor streams are said to have a periodicity of 12 years, caused by Jupiter.

Exploring the past

It was named after the mathematician and astronomer Edmond Halley (1656-1742), who became royal astronomer and head of the observatory in Greenwich in 1720 because of his services to determining the orbit of comets . While the appearance of comets was still considered unpredictable up to this time, Halley discovered in 1705 that the comet first observed by the Saxon farmer and astronomer Christoph Arnold in 1682 with earlier comet sightings in 1531 (described by Petrus Apianus ) and 1607 (described by Johannes Kepler and Ottmar Stab the Younger ) must be identical, and predicted its return for 1758.

After other researchers checked his calculations, the tail star was named "Halley". After Halley's death, Halley's comet actually returned: Its reappearance at that time was first observed on December 25, 1758 by the Saxon amateur astronomer Johann George Palitzsch . The arrival of the prediction that a comet would come with the same orbital data as the comets of 1531, 1607 and 1682 - which could not be seen without a telescope - was a great success of Newton's theory of gravity that was visible to all in 1758 - but it was also unique. A comet Halley predicted for 1789 did not come. It is also narrated that others "tried to be prophets" in vain. It was not until 1822 that a small comet ( 2P / Encke ) was also confirmed to be periodic.

When the comet returned in 1910, many people were frightened: shortly before the earth crossed the comet's tail on May 19, astronomers discovered the poisonous gas dicyan in it:

"While the scientific observations, as far as is known today, mostly only delivered negative results, the people, especially in the big cities, celebrated the passage in their own way, with drinking and scandal being the main thing [...]"

Representation in the past

In retrospect, it was recognized over time that the comet had been around since 240 BC. Had been observed at least 25 times. One of the first pictorial representations of the comet can be found on the Bayeux Tapestry (around 1070), the best known is perhaps that of the painter Giotto di Bondone (1266–1337), who certainly saw the comet in 1301 and also used it as a model for the first realistic depiction of a comet as the star of Bethlehem in the fresco Adoration of the Magi in the Cappella degli Scrovegni .

Exploration in the modern age

Stamp issue on the occasion of the Giotto Mission (Deutsche Bundespost 1986)

Halley's Comet was the target of five space probes from ESA , Japan and the Soviet Union in 1985 , some of them in international agreement. It is believed that comets are composed of a mixture of ice , rock, and dust , some of which originated from the early days of the solar system. Therefore the study of these celestial bodies has also become an area of ​​interest in cosmogony and cosmology .

Depiction of the comet on the mission logo of the failed flight STS-51-L of the Space Shuttle Challenger

While the Japanese probes Sakigake and Suisei approached the comet at 7,000,000 km and 150,000 km, the Soviet probes Vega  1 and Vega 2 crossed the comet's bow shock and penetrated to around 8,800 km and 8,000 km. The most successful was the ESA probe Giotto (named after the medieval painter mentioned above), which approached the core up to 596 km and was able to observe it directly.

In addition, for 1986 the implementation of two was NASA - Space Shuttle planned missions in which observations of the comet should be made: STS-51-L and STS-61-E . Since the Challenger used for the first mission was destroyed shortly after take-off and as a result no space shuttles were allowed to start until the cause of the accident was clarified, the second mission for which the Columbia was intended could no longer be carried out.

Halley's last picture for the time being

The last observation of the comet took place in March 2003 and even if 1P / Halley reached its point furthest from the sun ( aphelion ) in December 2023 , it would be visible with the same means (instruments / exposure time / "shift-added composite photo") of the European Southern Observatory .

Trivia

  • The life dates of the American writer Mark Twain correspond to almost two recurrences of Halley's Comet: Twain was born on November 30, 1835, exactly two weeks after the comet became visible. He died - almost exactly as he had hoped - on April 21, 1910, the day after the comet returned.
  • Halley's Comet of 1910 and the Johannesburg Comet contributed greatly to literary expressionism with the general insecurity that was triggered, “ panic-mongering ” and “ media scolding ” .
  • In 1986 the German writer Ernst Jünger (* March 29, 1895 - † February 17, 1998 ) traveled to Kuala Lumpur to see the comet again: “Halley was just as clearly in the sky as it was in Rehburg seventy-six years ago, when I had him with his parents and siblings. Kuala Lumpur , April 15, 1986 ”. This trip set the stage for his thoughts in Halley Two Times . He could compare the sight of 1910 with the 1986 return: "This time it seemed a little bigger to me, but just as unimpressive as it was back then - tailless, diffuse, like a ball of yarn."

See also

literature

Web links

Commons : Halley's Comet  - Collection of images, videos and audio files

Individual evidence

  1. ↑ NASA JPL Small-Body Database Browser: 1P / Halley. Retrieved May 14, 2010 .
  2. ^ J. Meeus: Mathematical Astronomy Morsels IV. Willmann-Bell, Richmond 2007, ISBN 978-0-943396-87-3 , pp. 210-223.
  3. ↑ Why we include a preview of Halley's next apparition after our current comet show, Comets and Discovery. Retrieved March 10, 2020 .
  4. ^ DK Yeomans, J. Rahe, RS Friday: The History of Comet Halley. In: Journal of the Royal Astronomical Society of Canada . Volume 80, April 1986, pp. 62-86. (on-line)
  5. ↑ z. B. Mark Kidger: Astronomical Enigmas. 2005, p. 78. (books.google.de)
  6. ↑ HORIZONS web interface. In: nasa.gov. Retrieved February 21, 2018 .
  7. ↑ Comets
  8. ↑ Snowballs In Space: An Introduction to Comets, their sizes and decay
  9. ↑ Meteorstrom-Kalender 2014 (www.meteoros.de; PDF; 683 kB), p. 7 and 13f. (accessed on November 7, 2014)
  10. ^ Edmond Halley: A synopsis of the astronomy of comets. P. 22. (accessed November 20, 2013)
  11. ^ Advertisement that Comet, published in 1682 and preached by Halley according to Newtonian theory for the present time, is really visible ... by a lover of star science. Leipzig 1759, also reprinted in slub-dresden / werkansicht new attempts at useful collections on natural and art history , Schneeberg 1759, p. 595. (accessed November 20, 2013)
  12. ↑ z. B. Eberhard Christian Kindermann : Astronomical description and news of the Comet 1746, and those still to come, which will appear in the said years. Dresden 1746, p. 14.
  13. ^ Sirius, Journal of Popular Astronomy. June 1910, p. 129.
  14. ↑ At the beginning of the 14th century there were several comets, see Donald K. Yeomans: Comets. New York et al. 1991, p. 400 f (English); Gary W. Kronk : Cometography: Volume 1, Ancient-1799. Cambridge 1999, p. 228 ff. (Books.google.de) (English); FT Schubert: Mixed writings on astronomy, physics, etc. Volume 4, 1826, p. 98. (books.google.de) ; François Arago : Conversations in the field of natural history. Volume 2, translated by Carl v. Remy, Stuttgart 1837, p. 110. (books.google.de)
  15. ^ Shift-Added Composite Photo with Comet Halley Image @ eso.org; Gary W. Kronk's Cometography - 1P / Halley (English)
  16. ↑ "Interestingly, when Comet Halley reaches its largest distance from the Sun in December 2023, about 35 AU, it will only be 2.5 times fainter than it is now. The comet would still have been detected within the present exposure time. This means that with the VLT, for the first time in the long history of this comet, the astronomers now possess the means to observe it at any point in its 76-year orbit! ", VLT Observes Famous Traveler at Record Distance @eso. org
  17. ↑ z. B. the poems End of the World by Jakob van Hoddis and Umbra Vitae / The people stand forward in the streets (see lyrik.antikoerperchen.de ) by Georg Heym or in the magazine Der Sturm from June 2, 1910 on page 110 under Miscellaneous : The Comet . (accessed November 24, 2013)
  18. ↑ In: Ernst Jünger: Diaries VIII. Radiations VI . Klett-Cotta, Stuttgart 2001, ISBN 3-608-93533-9 , p. 41.
  19. ↑ Review in the Spiegel , Book Description of the Verlag , p. 23 of the book. (accessed November 17, 2013)