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Timeline of discovery of Solar System planets and their moons

Related subjects Space (Astronomy); The Planets

This timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history.

Historically the naming of natural satellites did not always match the times of their discovery.

In the following tables, planetary satellites are indicated in bold type (e.g. Moon) while planets, major or minor, which directly circle the Sun are in italic type (e.g. Earth). The tables are sorted by publication/announcement date. Dates are annotated with the following symbols:

  • i: for date of first imaging (photography, etc.);
  • o: for date of first human visual observation, either through telescope or on photographic plate (the true "discovery" moment);
  • p: for date of announcement or publication.

*Note: Marked moons had complicated discoveries. Several moons took several years to be confirmed, and in several cases were actually lost and rediscovered. Others were found in Voyager photographs years after they were taken.

Colour legend

The planets and their natural satellites are marked in the following colors:

Planets

     Mercury      Venus      Earth and satellite      Mars and satellites      Jupiter and satellites      Saturn and satellites      Uranus and satellites      Neptune and satellites

Dwarf planets

     Ceres      Pluto and satellites      Eris and satellite

Prehistory

Prehistory
Name Image Planet/Number Designation References/Notes
Sun
Star In the Ptolemaic system, the Earth was believed to be at the centre of the cosmos. Seven planets were placed in orbit around it in an order of increasing distance from the Earth, first established by the Greek Stoics: the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn. This list included two objects, the Sun and the Moon, which are no longer considered to be planets; it also excluded the Earth.
Mercury
1st Planet In Nicolaus Copernicus' heliocentric system ( De Revolutionibus Orbium Coelestium, 1543) the Earth came to be considered a planet revolving with the other planets around the Sun, in the following order of distance from the Sun: Mercury, Venus, Earth, Mars, Jupiter, and Saturn. The Sun, now situated near the centre of revolution, was no longer considered a planet.
Venus
2nd Planet
Earth
3rd Planet
Mars
4th Planet
Jupiter
5th Planet
Saturn
6th Planet
Moon
Earth I In the Copernican system, the Moon was considered to be no longer a planet but a natural satellite of the Earth, and was the only body in that system whose revolution was not centered on the Sun.

17th century

17th century
Date Name Image Planet/Number Designation References/Notes
1610s
o: January 7, 1610
p: March 13, 1610
Callisto
Jupiter IV Galileo. The Galilean moons. Note: One of the moons may have been recorded by the Chinese astronomer Gan De in 364 BC. The Galilean satellites were the first celestial objects that were confirmed to orbit an object other than the Earth.
Io
Jupiter I
Europa
Jupiter II
o: January 11, 1610
p: March 13, 1610
Ganymede
Jupiter III
1650s
o: March 25, 1655
p: March 5, 1656
Titan
Saturn VI
Saturn II (1673–1684), Saturn IV (1686–1789)
Huygens. He first "published" his discovery as an anagram, sent out on June 13, 1655; later published in pamphlet form as De Saturni luna Observatio Nova and in full in Systema Saturnium (July 1659).
1670s
o: October 25, 1671
p: 1673
Iapetus
Saturn VIII
Saturn III (1673–1684), Saturn V (1686–1789), Saturn VII (1789–1848)
Cassini
o: December 23, 1672
p: 1673
Rhea
Saturn V
Saturn I (1673–1684), Saturn III (1686–1789)
1680s
o: March 21, 1684
p: April 22, 1686
Tethys
Saturn III
Saturn I (1686–1789)
Cassini. Together with his previous two discoveries, Cassini named these satellites Sidera Lodoicea.

In his work Kosmotheôros (published posthumously in 1698), Christiaan Huygens relates "Jupiter you see has his four, and Saturn his five Moons about him, all plac’d in their Orbits."

Dione
Saturn IV
Saturn II (1686–1789)
Date Name Image Planet/Number Designation References/Notes

18th century

18th century
Date Name Image Planet/Number Designation References/Notes
1780s
o: March 13, 1781
p: April 26, 1781
Uranus
7th Planet Herschel first reported the discovery of Uranus on April 26, 1781, initially believing it a comet
o: January 11, 1787
p: February 15, 1787
Titania
Uranus III Herschel. He later reported four more spurious satellites.
Oberon
Uranus IV
o: August 28, 1789
p: November 12, 1789
Enceladus
Saturn II Herschel
o: September 17, 1789
p: November 12, 1789
Mimas
Saturn I
Date Name Image Planet/Number Designation References/Notes

19th century

19th century
Date Name Image Planet/Number Designation References/Notes
1800s
o: January 1, 1801
p: January 24, 1801
Ceres
8th Planet (1801)
Asteroid (1851)
Dwarf planet (2006)
Giuseppe Piazzi. He first announced his discovery on January 24, 1801, in letters to fellow astronomers. The first formal publication was the September 1801 issue of the Monatliche Correspondenz.
1840s
o: September 23, 1846
p: November 13, 1846
Neptune
13th Planet (1846)
8th Planet (1851)
Galle and Le Verrier
o: October 10, 1846
p: November 13, 1846
Triton
Neptune I Lassell
o: September 16, 1848
p: October, 1848
Hyperion
Saturn VII Bond, Bond, Lassell
1850s
o: October 24, 1851 Ariel
Uranus I Lassell
Umbriel
Uranus II
1870s
o: August 12, 1877 Deimos
Mars II Hall
o: August 18, 1877 Phobos
Mars I
1890s
o: September 9, 1892
p: October 4, 1892
Amalthea
Jupiter V Barnard
i: August 16, 1898
o: March 17, 1899
Phoebe
Saturn IX Pickering
Date Name Image Planet/Number Designation References/Notes

Early 20th century

Early 20th century
Date Name Image Planet/Number Designation References/Notes
1900s
i: December 3, 1904
p: January 6, 1905
Himalia (Hestia 1955-1975)
Jupiter VI Perrine
i: January 2, 1905
p: February 27, 1905
Elara (Hera 1955-1975) Jupiter VII Perrine
i: January 27, 1908
o: February 28, 1908
p: March 1-6 1908
Pasiphaë (Poseidon 1955-1975) Jupiter VIII Melotte
1910s
i: July 21, 1914
p: September 17, 1914
Sinope (Hades 1955-1975) Jupiter IX Nicholson
1930s
i: January 23, 1930
o: February 18, 1930
p: March 13, 1930
Pluto
9th Planet (1930)
Dwarf planet (2006)
Tombaugh
i: July 6, 1938
p: August 1938
Lysithea (Demeter 1955-1975) Jupiter X Nicholson
i: July 30, 1938
p: August 1938
Carme (Pan 1955-1975) Jupiter XI Nicholson
1940s
i: February 16, 1948
p: June 1949
Miranda
Uranus V Kuiper
i: May 1, 1949
p: August 1949
Nereid
Neptune II Kuiper
1950s
i: September 28, 1951
p: December 1951
Ananke (Adrastea 1955-1975) Jupiter XII Nicholson
Date Name Image Planet/Number Designation References/Notes

Later 20th century

Later 20th century
Date Name Designation Image Planet/Number Designation References/Notes
1960s
i: December 15, 1966
p: January 3, 1967
Janus* S/1966 S 2
Saturn X Dollfus
(Dollfus may have seen either Janus or Epimetheus)
i: December 18, 1966
p: January 6, 1967
Epimetheus* S/1980 S 3 Saturn XI Walker
1970s
i: September 11, 1974
p: September 20, 1974
Leda Jupiter XIII Kowal
i: September 30, 1975
p: October 3, 1975
Themisto* S/1975 J 1 Jupiter XVIII Kowal
(Discovered and then lost)
i: April 13, 1978
o: June 22, 1978
Charon S/1978 P 1
Pluto I Christy
i: July 8, 1979
p: November 23, 1979
Adrastea S/1979 J 1
Jupiter XV Jewitt, Danielson / Voyager 2
1980s
Date Name Designation Image Planet/Number Designation References/Notes
i: February 26, 1980
p: March 6, 1980
Epimetheus* S/1980 S 3
Saturn XI
(Confirmed by Voyager 1)
i: March 1, 1980
p: March 6, 1980
Helene S/1980 S 6
Saturn XII Laques, Lecacheux
i: April 8, 1980
p: April 10, 1980
Telesto S/1980 S 13
Saturn XIII Smith, Reitsema, Larson, Fountain, Voyager 1
i: March 5, 1979
p: April 28, 1980
Thebe S/1979 J 2
Jupiter XIV Synnott, Voyager 1
i: February 19, 1980
p: June 6, 1980
Janus* S/1980 S 1
Saturn X
(Confirmed by Voyager 1)
i: March 13, 1980
p: July 31, 1980
Calypso S/1980 S 25
Saturn XIV Pascu, Seidelmann, Baum, Currie
i: March 4, 1979
p: August 26, 1980
Metis S/1979 J 3
Jupiter XVI Synnott, Voyager 1
o: October, 1980
p: October 31, 1980
Prometheus S/1980 S 27
Saturn XVI Collins, Voyager 1
Pandora S/1980 S 26
Saturn XVII Collins, Voyager 1
o: October, 1980
p: November 13, 1980
Atlas S/1980 S 28
Saturn XV Terrile, Voyager 1
i: May 24, 1981
p: 29 May 1981
Larissa* S/1981 N 1
= S/1989 N 2
Neptune VII Reitsema, Hubbard, Lebofsky, Tholen, Voyager 2
i: December 30, 1985
p: January 9, 1986
Puck S/1985 U 1
Uranus XV Synnott, Voyager 2
i: January 3, 1986
p: January 16, 1986
Juliet S/1986 U 2 Uranus XI Synnott, Voyager 2
Portia S/1986 U 1 Uranus XII Synnott, Voyager 2
i: January 9, 1986
p: January 16, 1986
Cressida S/1986 U 3 Uranus IX Synnott, Voyager 2
i: January 13, 1986
p: January 16, 1986
Desdemona S/1986 U 6 Uranus X Synnott, Voyager 2
Rosalind S/1986 U 4 Uranus XIII Synnott, Voyager 2
Belinda S/1986 U 5 Uranus XIV Synnott, Voyager 2
i: January 20, 1986
p: January 27, 1986
Cordelia S/1986 U 7 Uranus VI Terrile, Voyager 2
Ophelia S/1986 U 8 Uranus VII Terrile, Voyager 2
i: January 23, 1986
p: January 27, 1986
Bianca S/1986 U 9 Uranus VIII Smith, Voyager 2
i: June 16, 1989
p: July 7, 1989
Proteus S/1989 N 1
Neptune VIII Synnott, Voyager 2
i: July 28, 1989
p: August 2, 1989
Despina S/1989 N 3 Neptune V Synnott, Voyager 2
Galatea S/1989 N 4 Neptune VI Synnott, Voyager 2
i: September 18, 1989
p: September 29, 1989
Thalassa S/1989 N 5 Neptune IV Terrile, Voyager 2
Naiad S/1989 N 6 Neptune III Terrile, Voyager 2
1990s
Date Name Designation Image Planet/Number Designation References/Notes
i: August 22, 1981
p: July 16, 1990
Pan* S/1981 S 13
Saturn XVIII Showalter, Voyager 2
i: August 23, 1981
p: April 14, 1995
Pallene* (see below) S/1981 S 14   Gordon, Murray and Beurle
i: September 6, 1997
p: October 31, 1997
Caliban S/1997 U 1 Uranus XVI Gladman, Nicholson, Burns, Kavelaars
Sycorax S/1997 U 2 Uranus XVII Gladman, Nicholson, Burns, Kavelaars
i: January 18, 1986
p: May 18, 1999
Perdita* S/1986 U 10 Uranus XXV Karkoschka, Voyager 2
i: July 18, 1999
p: July 27, 1999
Setebos S/1999 U 1 Uranus XIX Kavelaars, Gladman, Holman, Petit, Scholl
Stephano S/1999 U 2 Uranus XX Gladman, Holman, Kavelaars, Petit, Scholl
i: July 18, 1999
p: September 4, 1999
Prospero S/1999 U 3 Uranus XVIII Holman, Kavelaars, Gladman, Petit, Scholl
2000s
Date Name Designation Image Planet/Number Designation References/Notes
i: October 6, 1999
p: July 20, 2000
Callirrhoe S/1999 J 1 Jupiter XVII Scotti, Spahr, McMillan, Larsen, Montani, Gleason, Gehrels
i: August 7, 2000
p: October 25, 2000
Ymir S/2000 S 1 Saturn XIX Gladman
Paaliaq S/2000 S 2 Saturn XX Gladman
i: September 23, 2000
p: October 25, 2000
Siarnaq S/2000 S 3 Saturn XXIX Gladman, Kavelaars
Tarvos S/2000 S 4 Saturn XXI Kavelaars, Gladman
i: August 7, 2000
p: November 18, 2000
Kiviuq S/2000 S 5 Saturn XXIV Gladman
i: September 23, 2000
p: November 18, 2000
Ijiraq S/2000 S 6 Saturn XXII Kavelaars, Gladman
i: November 21, 2000
p: November 25, 2000
Themisto* S/2000 J 1 Jupiter XVIII Sheppard, Jewitt, Fernández, Magnier (Rediscovered)
i: September 23, 2000
p: December 7, 2000
Thrymr S/2000 S 7 Saturn XXX Gladman, Kavelaars
Skathi S/2000 S 8 Saturn XXVII Kavelaars, Gladman
Mundilfari S/2000 S 9 Saturn XXV Gladman, Kavelaars
Erriapus S/2000 S 10 Saturn XXVIII Kavelaars, Gladman
i: November 9, 2000
p: December 19, 2000
Albiorix S/2000 S 11 Saturn XXVI Holman, Spahr
i: September 23, 2000
p: December 22, 2000
Suttungr S/2000 S 12 Saturn XXIII Gladman, Kavelaars
Date Name Designation Image Planet/Number Designation References/Notes

21st century

21st century
Date Name Designation Image Planet/Number Designation References/Notes

i: November 23, 2000
p: January 5, 2001

Kalyke S/2000 J 2   Jupiter XXIII Sheppard, Jewitt, Fernández, Magnier, Dahm, Evans
Iocaste S/2000 J 3   Jupiter XXIV
Erinome S/2000 J 4   Jupiter XXV
Harpalyke S/2000 J 5   Jupiter XXII
Isonoe S/2000 J 6   Jupiter XXVI
Praxidike S/2000 J 7   Jupiter XXVII
i: November 25, 2000
p: January 5, 2001
Megaclite S/2000 J 8   Jupiter XIX Sheppard, Jewitt, Fernández, Magnier, Dahm, Evans
Taygete S/2000 J 9   Jupiter XX
i: November 26, 2000
p: January 5, 2001
Chaldene S/2000 J 10   Jupiter XXI
i: December 5, 2000
p: January 5, 2001
  S/2000 J 11    
Date Name Designation Image Planet/Number Designation References/Notes
i: December 9, 2001
p: May 16, 2002
Hermippe S/2001 J 3   Jupiter XXX Sheppard, Jewitt, Kleyna
Eurydome S/2001 J 4   Jupiter XXXII
Sponde S/2001 J 5   Jupiter XXXVI
Kale S/2001 J 8   Jupiter XXXVII
i: December 10, 2001
p: May 16, 2002
Autonoe S/2001 J 1   Jupiter XXVIII
i: December 11, 2001
p: May 16, 2002
Thyone S/2001 J 2   Jupiter XXIX
Pasithee S/2001 J 6   Jupiter XXXVIII
Euanthe S/2001 J 7   Jupiter XXXIII
Orthosie S/2001 J 9   Jupiter XXXV
Euporie S/2001 J 10   Jupiter XXXIV
Aitne S/2001 J 11   Jupiter XXXI
i: August 13, 2001
p: September 30, 2002
Trinculo S/2001 U 1   Uranus XXI Holman, Kavelaars, Milisavljevic
i: October 31, 2002
p: December 18, 2002
Arche S/2002 J 1   Jupiter XLIII Sheppard, Meech, Hsieh, Tholen, Tonry
Date Name Designation Image Planet/Number Designation References/Notes
i: July 23, 2002
p: January 13, 2003
Sao S/2002 N 2   Neptune XI Holman, Kavelaars, Grav, Fraser, Milisavljevic
i: August 10, 2002
p: January 13, 2003
Halimede S/2002 N 1 Neptune IX
i: August 11, 2002
p: January 13, 2003
Laomedeia S/2002 N 3 Neptune XII
i: February 5, 2003
p: March 4, 2003
Eukelade S/2003 J 1   Jupiter XLVII Sheppard, Jewitt, Kleyna, Fernández, Hsieh
  S/2003 J 2  
S/2003 J 3
S/2003 J 4
i: February 6, 2003
p: March 4, 2003
  S/2003 J 5  
Helike S/2003 J 6 Jupiter XLV
i: February 8, 2003
p: March 4, 2003
Aoede S/2003 J 7 Jupiter XLI
i: February 8, 2003
p: March 6, 2003
Hegemone S/2003 J 8 Jupiter XXXIX Sheppard, Jewitt, Kleyna, Fernández
i: February 6, 2003
p: March 7, 2003
  S/2003 J 9   Sheppard, Jewitt, Kleyna, Fernández
S/2003 J 10
Kallichore S/2003 J 11   Jupiter XLIV
i: February 8, 2003
p: March 7, 2003
  S/2003 J 12    
i: February 9, 2003
p: April 2, 2003
Cyllene S/2003 J 13   Jupiter XLVIII Sheppard, Jewitt, Kleyna
i: February 8, 2003
p: April 3, 2003
Kore S/2003 J 14   Jupiter XLIX Sheppard, Jewitt, Kleyna
i: February 6, 2003
p: April 3, 2003
  S/2003 J 15   Sheppard, Jewitt, Kleyna, Fernández
S/2003 J 16 Gladman, Sheppard, Jewitt, Kleyna, Kavelaars, Petit, Allen
i: February 8, 2003
p: April 3, 2003
  S/2003 J 17   Gladman, Sheppard, Jewitt, Kleyna, Kavelaars, Petit, Allen
i: February 6, 2003
p: April 4, 2003
  S/2003 J 18   Gladman, Kavelaars, Petit, Allen, Sheppard, Jewitt, Kleyna
i: February 5, 2003
p: April 8, 2003
Narvi S/2003 S 1   Saturn XXXI Sheppard, Jewitt, Kleyna
i: February 6, 2003
p: April 12, 2003
  S/2003 J 19   Gladman, Sheppard, Jewitt, Kleyna, Kavelaars, Petit, Allen
i: February 9, 2003
p: April 14, 2003
Carpo S/2003 J 20 Jupiter XLVI Sheppard, Gladman, Kavelaars, Petit, Allen, Jewitt, Kleyna
i: February 6, 2003
p: May 29, 2003
Mneme S/2003 J 21 Jupiter XL Sheppard, Jewitt, Kleyna, Gladman, Kavelaars, Petit, Allen
i: January 18, 1986
p: September 3, 2003
Perdita* S/1986 U 10 Uranus XXV Karkoschka (Recovered by the Hubble Space Telescope)
i: August 29, 2003
p: September 3, 2003
Psamathe S/2003 N 1   Neptune X Jewitt, Kleyna, Sheppard, Holman, Kavelaars
i: August 25, 2003
p: September 25, 2003
Mab S/2003 U 1   Uranus XXVI Showalter, Lissauer
Cupid S/2003 U 2   Uranus XXVII
i: August 13, 2001
p: September 30, 2003
Ferdinand* S/2001 U 2 Uranus XXIV 2001: Holman, Kavelaars, Milisavljevic;
2003: Scott S. Sheppard, David C. Jewitt
i: August 14, 2002
p: September 30, 2003
Neso* S/2002 N 4   Neptune XIII Holman, Kavelaars, Grav, Fraser, Milisavljevic
i: August 13, 2001
p: October 8, 2003
Francisco* S/2001 U 3   Uranus XXII Holman, Kavelaars, Milisavljevic, Gladman
i: August 29, 2003
p: October 9, 2003
Margaret S/2003 U 3   Uranus XXIII Sheppard, Jewitt
Date Name Designation Image Planet/Number Designation References/Notes
i: February 9, 2003
p: January 24, 2004
Thelxinoe* S/2003 J 22   Jupiter XLII Sheppard, Jewitt, Kleyna, Gladman, Kavelaars, Petit, Allen
(From images taken in 2003)
i: February 6, 2003
p: January 31, 2004
  S/2003 J 23*   Sheppard, Jewitt, Kleyna, Fernández
i: June 1, 2004
p: August 16, 2004
Methone* S/2004 S 1 Saturn XXXII Porco, Charnoz, Brahic, Dones / Cassini-Huygens
Pallene S/2004 S 2
=S/1981 S 14
Saturn XXXIII
i: June 21, 2004
p: September 9, 2004
  S/2004 S 3
Murray, Porco et al. / Cassini-Huygens
i: June 21?, 2004
p: September 9, 2004
  S/2004 S 4   Spitale, Porco et al. / Cassini-Huygens
i: October 21, 2004
o: October 24, 2004
p: November 8, 2004
Polydeuces S/2004 S 5
Saturn XXXIV Porco et al. / Cassini-Huygens
i: October 28, 2004
p: November 8, 2004
  S/2004 S 6
 
Date Name Designation Image Planet/Number Designation References/Notes
i: December 12, 2004
p: May 3, 2005
  S/2004 S 7     Sheppard, Jewitt, Kleyna, Marsden
Fornjot S/2004 S 8 Saturn XLII
Farbauti S/2004 S 9 Saturn XL
Aegir S/2004 S 10 Saturn XXXVI
Bebhionn S/2004 S 11 Saturn XXXVII
S/2004 S 12  
S/2004 S 13
Hati S/2004 S 14 Saturn XLIII
Bergelmir S/2004 S 15 Saturn XXXVIII
i: December 13, 2004
p: May 3, 2005
Fenrir S/2004 S 16   Saturn XLI
  S/2004 S 17
Bestla S/2004 S 18 Saturn XXXIX
i: May 1, 2005
p: May 6, 2005
Daphnis S/2005 S 1
Saturn XXXV Porco et al. / Cassini-Huygens
i: October 21, 2003
o: January 5, 2005
p: July 29, 2005
Eris 2003 UB313 Dwarf planet Brown, Trujillo and Rabinowitz
i: September 10, 2005
p: October 3, 2005
Dysnomia S/2005 (2003 UB313) 1 Eris I Brown, van Dam, Bouchez, Le Mignant, Campbell,
Chin, Conrad, Hartman, Johansson, Lafon, Rabinowitz,
Stomski, Summers, Trujillo, Wizinowich
i: May 15, 2005
o: June 15, 2005
p: October 31, 2005
Nix S/2005 P 2   Pluto II Weaver, Stern, Mutchler, Steffl, Buie, Merline,
Spencer, Young, Young
Hydra S/2005 P 1   Pluto III
Date Name Designation Image Planet/Number Designation References/Notes
i: December 12, 2004
o: March 6, 2006(?)
p: June 26, 2006
Hyrrokkin S/2004 S 19   Saturn XLIV Sheppard, Jewitt, Kleyna
i: January 4, 2006
o: March 6, 2006(?)
p: June 26, 2006
  S/2006 S 1   Sheppard, Jewitt, Kleyna
Kari S/2006 S 2 Saturn XLV
i: January 5, 2006
o: March 6, 2006 (?)
p: June 26, 2006
S/2006 S 3  
Greip S/2006 S 4 Saturn LI
Loge S/2006 S 5 Saturn XLVI
Jarnsaxa S/2006 S 6 Saturn L
Surtur S/2006 S 7 Saturn XLVIII
Skoll S/2006 S 8 Saturn XLVII
Date Name Designation Image Planet/Number Designation References/Notes
i: January 5, 2006
o: January 16, 2007 (?)
p: April 13, 2007
Tarqeq S/2007 S 1   Saturn LII Sheppard, Jewitt, Kleyna
i: January 18, 2007
o:  
p: May 1, 2007
  S/2007 S 2     Sheppard, Jewitt, Kleyna
  S/2007 S 3    
i: June, 2004
o: May 30, 2007
p: July 18, 2007
Anthe S/2007 S 4   Saturn XLIX Porco / Cassini-Huygens
Date Name Designation Image Planet/Number Designation References/Notes
Retrieved from " http://en.wikipedia.org/wiki/Timeline_of_discovery_of_Solar_System_planets_and_their_moons"