View source for Comet Donati

{{Short description|Non-periodic comet}}
{{Distinguish|C/1855 L1 (Donati)}}
{{About|the "Great Comet of 1858"|other comets discovered by Giovanni Battista Donati|Comet Donati (disambiguation)}}
{{Infobox comet
| name            = C/1858 L1 (Donati)<br>(Great Comet of 1858)
| image           = William Turner of Oxford 1859 Donati's Comet.jpg
| caption         = ''Donati's Comet, Oxford, 7:30 p.m., 5 Oct. 1858'' by [[William Turner (artist)|William Turner]]
| discoverer      = [[Giovanni Battista Donati]]
| discovery_date  = 1858
| designations    = 1858 VI
| orbit_ref       = {{r|barycenter|jpldata}}
| epoch           = 8 October 1858 ([[Julian day|JD]] 2399960.5)
| observation_arc = 270 days
| obs             = 1,000
| semimajor       = ~145 AU
| perihelion      = 0.578 AU
| aphelion        = ~289 [[Astronomical Unit|AU]]
| eccentricity    = 0.996295
| period          = ~1,739 [[Julian year (astronomy)|yr]] (outbound)
| inclination     = 116.951°
| asc_node        = 167.304°
| arg_peri        = 129.144°
| tjup            = –0.394
| physical_ref    = {{r|Fernández_2012|Moreno_2025}}
| mean_radius     = {{cvt|2.96|km|mi}}{{efn|Calculated mean radius using the formula: <math>\log_{10}\,(\,R\,)\ =\;0.9 +\;0.13 (\,H\,)</math>{{r|Fernández_2012}}<br>Where <math>\,H\,</math> is the comet's absolute total magnitude (M1)}}
| rotation        = 4.6 hours
| M1              = 3.3
| M2              = 
| magnitude       = 0.0–1.0<br>{{small|(1858 apparition)}}{{r|Yeomans_2007}}
| last_p          = 30 September 1858
| next_p          = ≈3600
}}
'''Comet Donati''', or '''Donati's Comet''', [[Astronomical naming conventions#Comets|formally designated]] '''C/1858 L1''' and '''1858 VI''', is a [[List of non-periodic comets|long-period]] [[comet]] named after the [[Italy|Italian]] [[astronomer]] [[Giovanni Battista Donati]] who first observed it on June 2, 1858. After the [[C/1811 F1|Great Comet of 1811]], it was the most brilliant comet that appeared in the 19th century. It was also the first comet to be photographed.

==Discovery and observations==
[[File:Donatigiovanbattista.jpg|thumb|left|Donati, the comet's discoverer.]]
[[File:Diagram of the Comet of 1858 Discovered by Donati, June 2nd. RMG PT4028.png|thumb|left|Diagram for locating the comet, printed a week before nearest approach.]]
Donati first observed the comet on 2 June from the Florence Observatory: it was initially visible as a small nebula-like object of magnitude 7 near the "head" of [[Leo (constellation)|Leo]].<ref name=stoyan126>Stoyan, ''Atlas of Great Comets'', Cambridge University Press, 2015, p.126</ref> By mid-August it had brightened sufficiently to be visible to the naked eye.<ref name=bortle>Bortle, [http://www.icq.eps.harvard.edu/bortle.html "The Bright Comet Chronicles"], Harvard University, accessed February 14, 2017<!--or February 17, 2014 – date format was ambiguous--></ref>

In September it passed into [[Ursa Major]]. For much of its apparition it occupied a unique position (among great comets) in the sky<ref name=bortle/> and was particularly well placed for Northern Hemisphere viewers.<ref name=stoyan126/>

It was nearest the [[Earth]] on October 10, 1858, and for much of October was a brilliant object with a long, [[scimitar]]-like dust tail and prominent gas tail. It remained a naked-eye object until November for Southern Hemisphere observers.<ref name=bortle/> The final observation was by William Mann, chief assistant at the [[Royal Observatory, Cape of Good Hope]], who detected it as a faint nebulosity on March 4, 1859.<ref name=kronk273>Kronk, ''Cometography'', v.2, p.273</ref>

During its apparition the comet was particularly closely studied by the astronomer [[George Phillips Bond]] and his father [[William Cranch Bond]]. G. P. Bond incorporated these observations and those of many other astronomers into a monograph, ''An Account of the Great Comet of 1858'', which remains his most important scientific work and for which he was awarded the Gold Medal of the [[Royal Astronomical Society]], being the first American to receive the award.<ref name=trimble147>Trimble et al., eds. (2007), ''Biographical Encyclopedia of Astronomers'', p.147</ref>

===Comet photographed===
Donati's Comet was successfully photographed on September 27 by W. Usherwood, a portrait photographer at [[Walton-on-the-Hill]], Surrey, using a 7-second exposure with an {{f/}}2.4 portrait lens, the first time a comet had been photographed.<ref name=kronk270>Kronk, ''Cometography'', v.2, p.270</ref> Usherwood's photograph, which has not survived, showed the bright region around the comet's nucleus and a part of the tail. G. P. Bond also successfully photographed the comet on September 28 at [[Harvard College Observatory]], the first comet photograph through a telescope. He made several attempts with increasing exposure times, finally achieving a discernible image. He later wrote, "only the nucleus and a little nebulosity 15" in diameter acted on the plate in an exposure of six minutes".<ref>{{citation | url=http://adsabs.harvard.edu/full/1996JHA....27..129P| title= The Earliest Comet Photographs | publisher=SAO/NASA Astrophysics Data System | bibcode= 1996JHA....27..129P | access-date=August 17, 2013 | last1= Pasachoff | first1= Jay M. | last2= Olson | first2= Roberta J. M. | last3= Hazen | first3= Martha L. | journal= Journal for the History of Astronomy | date= 1996 | volume= 27 | page= 129 | doi= 10.1177/002182869602700202 }}</ref>

===Orbital calculations===
{| class="wikitable floatright" style="font-size: 0.9em;"
|+Barycentric orbital periods when outside planetary perturbations<ref name=barycenter/>
!
! [[Epoch (astronomy)|Epoch]]<br />1600
! Epoch<br />2200
|-
|[[Orbital period]] || 1966 yr || 1739 yr
|-
|[[Orbital eccentricity]] || 0.9963 || 0.9960
|-
|[[Aphelion]] || 313 [[Astronomical unit|AU]] || 289 AU
|}

Orbits for the comet were calculated by Friedrich Emil von Asten and [[George William Hill]], the latter's based on nearly 1000 positions.<ref name=kronk275>Kronk, ''Cometography'', v2, p.275</ref> The comet had an [[orbital inclination]] of 116.9°.<ref name=jpldata/> With an epoch 2200 barycentric orbital period approximated at 1739 years,<ref name=barycenter/> it is estimated that Donati's Comet will not be seen passing by Earth again until [[List of future astronomical events#4th to 8th millennia|somewhere around the year 3600]]. {{Asof|2023}}, [[JPL Horizons On-Line Ephemeris System|JPL Horizons]] estimates that the comet is {{Convert|147|AU|e9km|sigfig=2|abbr=unit|lk=on}} from the Sun and continuing to move away from the Sun at {{convert|2.4|km/s|mph|abbr=on}}.<ref name=Horizons>{{cite web
  |title=JPL Horizons On-Line Ephemeris for Comet C/1858 L1 (Donati) 2023–2030
  |author=JPL Horizons On-Line Ephemeris System
  |url=https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%271858+L1%27&START_TIME=%272023-01-01%27&STOP_TIME=%272030-01-01%27&STEP_SIZE=%271%20year%27&QUANTITIES=%2719,22%27
  |access-date=2023-07-27}}</ref>

The comet's orbit lies very close to that of [[Venus (planet)|Venus]], with the minimum intersection distance being {{convert|0.0047|AU}}, which is smallest known distance a great comet can approach a terrestrial planet. It is possible the comet produces a strong [[meteor shower]] at the northern hemisphere.<ref>{{cite journal |last1=Christou |first1=A. A. |title=Annual meteor showers at Venus and Mars: lessons from the Earth |journal=Monthly Notices of the Royal Astronomical Society |date=March 2010 |volume=402 |issue=4 |pages=2759–2770 |doi=10.1111/j.1365-2966.2009.16097.x|doi-access=free |bibcode=2010MNRAS.402.2759C }}</ref>

==In art and culture==
[[File:CometDonati.jpg|thumb|left|The comet with both gas and dust tails depicted.]]
[[File:Donati's Comet.jpg|thumb|left|Donati's Comet inspired a large number of artists, such as [[James Poole (painter)|James Poole]].]]

Donati's Comet is considered to be one of the most beautiful comets observed,<ref name=burnham69>Burnham, ''Great Comets'', 2000, p.69</ref> and was one of the brightest of the century, making a strong impression both on artists and the general public. After a prior period of hysteria on the subject of comets, especially in [[Paris]] (caused partly by incorrect calculations by [[John Russell Hind]] which suggested that one would strike the Earth in June 1857) Donati's Comet went on to be the most-observed of the century due to its excellent visibility in dark skies for Northern Hemisphere viewers, particularly in Europe, and fine weather in September and October.<ref name=stoyan127/> [[William Henry Smyth]], an English astronomer, recalled it as "one of the most beautiful objects that I have ever seen".<ref name=stoyan127>Stoyan, 2015, p.127</ref> Donati himself, a relatively obscure figure, was propelled to the status of an astronomical hero, and the comet helped cultivate a general enthusiasm for astronomy among the public.<ref name=gasperini340>Gasperini, "The worldwide impact of Donati's comet
on art and society in the mid-19th century", ''Proceedings of IAU Symposium'' 2011, 340</ref>

Donati's Comet appears as a streak and star in the early evening sky of a painting by [[William Dyce]], ''[[Pegwell Bay, Kent – a Recollection of October 5th 1858]]''.<ref>Rothstein, Edward (March 2, 2009). [https://www.nytimes.com/2009/03/03/arts/design/03muse.html "Darwin's wake splashed artists, too"]. ''The New York Times''. Accessed March 4, 2009.</ref> It was featured in a number of sketches and at least one painting by [[William Turner (artist)|William Turner of Oxford]], and in a painting, "The Comet of 1858, as seen from the Heights of Dartmoor", by [[Samuel Palmer]]. ''The Comet at Yell'ham'', a 1902 poem by [[Thomas Hardy]], was inspired by his recollections of Donati's Comet.<ref name=gasperini343>Gasperini, 2011, 343</ref>

[[Abraham Lincoln]], then a candidate for a seat in the [[U.S. Senate]], sat up on the porch of his hotel in [[Jonesboro, Illinois]], to see "Donti's Comet" on September 14, 1858, the night before the third of his [[Lincoln-Douglas debates|historic debates]] with [[Stephen Douglas]].<ref>White, Ronald C. Jr. (2009). ''A. Lincoln: A Biography'', first edition. New York: Random House. p  273.</ref>

In his journals of the Malay Archipelago, naturalist [[Alfred Russel Wallace]] writes of seeing the comet in October 1858 off the island of [[Tidore]] in Indonesia. "I observed what seemed a fire of remarkable whiteness on the very summit of the hill&nbsp;... the magnificent comet which was at the same time, astonishing all Europe. The nucleus presented to the naked eye a distinct disc of brilliant white light, from which the tail rose at an angle of about 30° or 35° with the horizon, curving slightly downwards, and terminating in a broad brush of faint light, the curvature of which diminished till it was nearly straight at the end. The portion of the tail next the comet appeared three or four times as bright as the most luminous portion of the milky way, and what struck me as a singular feature was that its upper margin, from the nucleus to very near the extremity, was clearly and almost sharply defined, while the lower side gradually shaded off into obscurity."<ref>Wallace, Alfred Russel (1869). ''The Malay Archipelago''. Chapter XXIII.</ref>

The influence of the comet, particularly in visual and design terms, was such that traces of its appearance can be found in magazine and commercial illustrations, household objects, children's books and other items up until the early years of the 20th century.<ref name=gasperini340/>
{{Clear|left}}

== References ==
=== Notes ===
{{Notelist}}

=== Citations ===
{{Reflist|refs=

<ref name=barycenter>{{cite web
  |title=Barycentric Osculating Orbital Elements for Comet C/1858 L1 (Donati)
  |author=[[JPL Horizons On-Line Ephemeris System|Horizons]] output
  |url=https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%271858+L1%27&TABLE_TYPE=%27ELEMENTS%27&START_TIME=%271600-01-01%27&STOP_TIME=%272200-01-01%27&STEP_SIZE=%27600%20years%27&CENTER=%27@0%27&OUT_UNITS=%27AU-D%27
  |accessdate=2023-07-27}} (epoch 2200 is PR= 6.35E+05 / 365.25 days = 1739 years)</ref>

<ref name="Fernández_2012">{{cite journal
| author1= J. A. Fernández
| author2= A. Sosa
| title= Magnitude and size distribution of long-period comets in Earth-crossing or approaching orbits
| journal= Monthly Notices of the Royal Astronomical Society
| year= 2012
| volume= 423
| issue= 2
| pages= 1674–1690
| doi= 10.1111/j.1365-2966.2012.20989.x
| doi-access= free | arxiv= 1204.2285
}}
</ref>

<ref name="jpldata">{{cite web
| title= C/1858 L1 (Donati) – JPL Small-Body Database Lookup
| url= https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1858L1
| website= ssd.jpl.nasa.gov
| publisher= [[Jet Propulsion Laboratory]]
| access-date= 15 May 2011 }}
</ref>

<ref name="Moreno_2025">{{cite journal
| author1= F. Moreno
| author2= E. Jehin
| title= Dust shells and dark linear structures on dust tails of historical and recent long-period comets
| journal= Astronomy & Astrophysics
| year= 2025
| volume= 696
| issue= A43
| pages= 1–7
| bibcode= 2025A&A...696A..43M
| arxiv= 2503.10121
| doi= 10.1051/0004-6361/202553986
| doi-access= free }}
</ref>

<ref name="Yeomans_2007">{{cite web
| author1= D. K. Yeomans
| title= Great Comets in History
| url= https://ssd.jpl.nasa.gov/sb/great_comets.html
| website= ssd.jpl.nasa.gov
| publisher= [[Jet Propulsion Laboratory]]
| date= April 2007 }}
</ref>

}}

{{Refbegin}}
* [https://web.archive.org/web/20041015153824/http://ssd.jpl.nasa.gov/data/ELEMENTS.COMET JPL DASTCOM Comet Table]
{{Refend}}

==External links==
* {{JPL Small Body|name=C/1858 L1|id=1000821}}
* [https://hdr-astrophotography.com/simulations-of-past-comets-1700-1899/ HDR Astrophotography: Simulations Atlas of Past Comets (1700 to 1899)] by Nicolas Lefaudeux

{{Comets}}
{{Authority control}}

{{DEFAULTSORT:Donati, 1858 L1}}
[[Category:Non-periodic comets]]
[[Category:Astronomical objects discovered in 1858|18580602]]
[[Category:Great comets]]