Timeline of discovery of Solar System planets and their natural satellites
Encyclopedia : T : TI : TIM : Timeline of discovery of Solar System planets and their natural satellites
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. When two dates are given, the first is publication, the second is the discovery observation's date. If a third date appears, it is the actual date of discovery (the date on which the discoverer first realised what he was looking at).
*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.
Color code
The planets and their natural satellites are marked in the following colors:| Mercury | Venus | Earth and satellite | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mars and satellites | Jupiter and satellites | Saturn and satellites | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Uranus and satellites | Neptune and satellites | Pluto and satellites |
Prehistory
| Prehistory | |||||
|---|---|---|---|---|---|
| Date | Name | Designation | Image | Planet/Number Designation | References/Notes |
| Unknown | Sun | In the Ptolemaic system, the Earth was believed to be at the center 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. | |||
| Unknown | Mercury | Sol I | 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 center of revolution, was no longer considered a planet. | ||
| Venus | Sol II | ||||
| Earth | Sol III | ||||
| Mars | Sol IV | ||||
| Jupiter | Sol V | ||||
| Saturn | Sol VI | ||||
| Unknown | 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 | Designation | Image | Planet/Number Designation | References/Notes |
| 1610s | |||||
| March 13 1610 / January 7 1610 | Callisto | | Jupiter IV | Galileo, Sidereus Nuncius, [link]. 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 | |||
| March 13 1610 / January 11 1610 | Ganymede | Jupiter III | |||
| 1650s | |||||
| March 5 1656 / March 25 1655 | Titan | Saturn VI | Huygens, [link]. Huygens first "published" his discovery as an anagram, sent out on June 13, 1655; later published in full in his [Systema Saturnium]. | ||
| 1670s | |||||
| October 25 1671 | Iapetus | | Saturn VIII | Cassini, [link]. Cassini published these two discoveries in Découverte de deux nouvelles planetes autour de Saturne (Sebastien Mabre-Cramoisy, 1673), translated as A Discovery of Two New Planets about Saturn, Made in the Royal Parisian Observatory by Signor Cassini, Philosophical Transactions 8 (1673), pp. 5178-5185. There may be earlier publications within the Journal des scavans. | |
| December 23, 1672 | Rhea |
| Saturn V | ||
| 1680s | |||||
| March 21, 1684 | Tethys | | Saturn III | Cassini. Cassini published these two discoveries on April 22, 1686, judging by An Extract of the Journal Des Scavans of April 22 st. N. 1686, Giving an Account of Two New Satellites of Saturn, Discovered Lately by Mr. Cassini at the Royal Observatory at Paris, Philosophical Transactions 16 (1686-1692) pp. 79-85. 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 | |||
| Date | Name | Designation | Image | Planet/Number Designation | References/Notes |
18th century
| 18th century | |||||
|---|---|---|---|---|---|
| Date | Name | Designation | Image | Planet/Number Designation | References/Notes |
| 1780s | |||||
| March 13 1781 | Uranus | Sol VII | Herschel [link]. Herschel first reported the discovery of Uranus on April 26, 1781, hedging by calling it a "comet": Account of a Comet, By Mr. Herschel, F. R. S.; Communicated by Dr. Watson, Jun. of Bath, F. R. S., Philosophical Transactions of the Royal Society of London, Volume 71, pp. 492-501. | ||
| January 11 1787 | Titania | | Uranus III | Herschel | |
| Oberon | Uranus IV | Herschel | |||
| August 28 1789 | Enceladus | | Saturn II | Herschel | |
| September 17 1789 | Mimas | Saturn I | Herschel [link] | ||
| Date | Name | Designation | Image | Planet/Number Designation | References/Notes |
19th century
| 19th century | |||||
|---|---|---|---|---|---|
| Date | Name | Designation | Image | Planet/Number Designation | References/Notes |
| 1840s | |||||
| September 23, 1846 | Neptune | Sol VIII | Galle and Le Verrier [link] | ||
| October 10, 1846 | Triton |
| Neptune I | Lassell [link] [link] | |
| September 16, 1848 | Hyperion | Saturn VII | Bond, Bond, Lassell [link] [link] | ||
| 1850s | |||||
| October 24, 1851 | Ariel |
| Uranus I | Lassell [link] | |
| Umbriel |
| Uranus II | Lassell [link] | ||
| 1870s | |||||
| August 12, 1877 | Deimos | Mars II | Hall [link] [link] [link] | ||
| August 18, 1877 | Phobos |
| Mars I | Hall [link] [link] [link] | |
| 1890s | |||||
| October 4 1892 / September 9, 1892 | Amalthea | | Jupiter V | Barnard [link] | |
| March 17 1899 / August 16, 1898 | Phoebe | | Saturn IX | Pickering [link] [link] | |
| Date | Name | Designation | Image | Planet/Number Designation | References/Notes |
20th century
| 20th century | |||||
|---|---|---|---|---|---|
| Date | Name | Designation | Image | Planet/Number Designation | References/Notes |
| 1900s | |||||
| January 6 1905 / December 3 1904 | Himalia (formerly known as Hestia) | Jupiter VI | Perrine [link] [link] [link] [link] | ||
| February 27 1905 / January 2, 1905 | Elara (formerly known as Hera) | Jupiter VII | Perrine [link] [link] [link] | ||
| March 1-6 1908 / January 27, 1908 | Pasiphaë (formerly known as Poseidon) | Jupiter VIII | Melotte [link] [link] | ||
| 1910s | |||||
| July 21, 1914 | Sinope (formerly known as Hades) | Jupiter IX | Nicholson [link] | ||
| 1930s | |||||
| March 13 1930 / January 23 1930 / February 18, 1930 | Pluto | Sol IX | Tombaugh [link] | ||
| July 6, 1938 | Lysithea (formerly known as Demeter) | Jupiter X | Nicholson [link] | ||
| July 30, 1938 | Carme (formerly known as Pan) | Jupiter XI | Nicholson [link] | ||
| 1940s | |||||
| February 16, 1948 | Miranda | Uranus V | Kuiper [link] | ||
| May 1, 1949 | Nereid | Neptune II | Kuiper [link] [link] | ||
| 1950s | |||||
| September 28, 1951 | Ananke (formerly known as Adrastea) | Jupiter XII | Nicholson [link] | ||
| 1960s | |||||
| December 15 1966 | Janus* | S/1966 S 2 | Saturn X | Dollfus [link] [link] [link] [link] [link] [link] (Dollfus may have seen either Janus or Epimetheus) | |
| December 18 1966 | Epimetheus* |
| Saturn XI | Walker [link] | |
| 1970s | |||||
| September 20 1974 / September 11, 1974 | Leda | Jupiter XIII | Kowal [link] [link] [link] [link] | ||
| October 3 1975 / September 30, 1975 | Themisto* | S/1975 J 1 | Jupiter XVIII | Kowal [link] [link] [link] (Discovered and then lost) | |
| April 13, 1978 | Charon | S/1978 P 1 | Pluto I | Christy [link] [link] | |
| November 23 1979 / July 8, 1979 | Adrastea | S/1979 J 1 | Jupiter XV | Jewitt, Danielson / Voyager 2 [link] [link] [link] [link] [link] [link] | |
| 1980s | |||||
| Date | Name | Designation | Image | Planet/Number Designation | References/Notes |
| January 19, 1980 | Janus* | S/1980 S 1 | Saturn X | [link] [link] [link] [link] [link] (Confirmed by Voyager 1) | |
| January 26, 1980 | Epimetheus* | S/1980 S 3 | | Saturn XI | [link] [link] [link] [link] [link] (Confirmed by Voyager 1) |
| March 1, 1980 | Helene | S/1980 S 6 | Saturn XII | Laques, Lecacheux [link] [link] [link] [link] | |
| March 13, 1980 | Calypso | S/1980 S 25 | Saturn XIV | Pascu, Seidelmann, Baum, Currie [link] [link] | |
| April 8, 1980 | Telesto | S/1980 S 13 | Saturn XIII | Smith, Reitsema, Larson, Fountain, Voyager 1 [link] [link] | |
| April 28, 1980/ March 5, 1979 | Thebe | S/1979 J 2 | Jupiter XIV | Synnott, Voyager 1 [link] [link] | |
| August 26, 1980/ March 4, 1979 | Metis | S/1979 J 3 | Jupiter XVI | Synnott, Voyager 1 [link] | |
| October, 1980 | Atlas | S/1980 S 28 | Saturn XV | Terrile, Voyager 1 [link] | |
| Prometheus | S/1980 S 27 | Saturn XVI | Collins, Voyager 1 [link] | ||
| Pandora | S/1980 S 26 | Saturn XVII | Collins, Voyager 1 [link] | ||
| December 30, 1985 | Puck | S/1985 U 1 |
| Uranus XV | Synnott, Voyager 2 [link] |
| January 3, 1986 | Juliet | S/1986 U 2 | Uranus XI | Synnott, Voyager 2 [link] [link] | |
| Portia | S/1986 U 1 | Uranus XII | Synnott, Voyager 2 [link] [link] | ||
| January 9, 1986 | Cressida | S/1986 U 3 | Uranus IX | Synnott, Voyager 2 [link] [link] | |
| January 13, 1986 | Desdemona | S/1986 U 6 | Uranus X | Synnott, Voyager 2 [link] [link] | |
| Rosalind | S/1986 U 4 | Uranus XIII | Synnott, Voyager 2 [link] [link] | ||
| Belinda | S/1986 U 5 | Uranus XIV | Synnott, Voyager 2 [link] [link] | ||
| January 20, 1986 | Cordelia | S/1986 U 7 | Uranus VI | Terrile, Voyager 2 [link] | |
| Ophelia | S/1986 U 8 | Uranus VII | Terrile, Voyager 2 [link] | ||
| January 23, 1986 | Bianca | S/1986 U 9 | Uranus VIII | Smith, Voyager 2 [link] | |
| July 7 1989 / < June 16, 1989 | Proteus | S/1989 N 1 |
| Neptune VIII | Synnott, Voyager 2 [link] [link] |
| August 2 1989 / < July 28, 1989 | Larissa | S/1989 N 2 | Neptune VII | Reitsema, Hubbard, Lebofsky, Tholen, Voyager 2 [link] | |
| Despina | S/1989 N 3 | Neptune V | Synnott, Voyager 2 [link] | ||
| Galatea | S/1989 N 4 | Neptune VI | Synnott, Voyager 2 [link] | ||
| September 29 1989 / < September 18, 1989 | Thalassa | S/1989 N 5 | Neptune IV | Terrile, Voyager 2 [link] | |
| Naiad | S/1989 N 6 | Neptune III | Terrile, Voyager 2 [link] | ||
| 1990s | |||||
| Date | Name | Designation | Image | Planet/Number Designation | References/Notes |
| July 16, 1990 / August 22, 1981 | Pan* | S/1981 S 13 | Saturn XVIII | Showalter, Voyager 2 [link] | |
| April 14, 1995 / August 23, 1981 | S/1981 S 14 (see Methone below) | Saturn | Gordon, Murray and Beurle [link] [link] | ||
| September 6, 1997 | Caliban | S/1997 U 1 | Uranus XVI | Gladman, Nicholson, Burns, Kavelaars [link] | |
| Sycorax | S/1997 U 2 | Uranus XVII | Gladman, Nicholson, Burns, Kavelaars [link] | ||
| May 18, 1999 / January 18, 1986 | Perdita* | S/1986 U 10 | Uranus XXV | Karkoschka, Voyager 2 [link] | |
| July 18, 1999 | Setebos | S/1999 U 1 | Uranus XIX | Kavelaars, Gladman, Holman, Petit, Scholl [link] | |
| Stephano | S/1999 U 2 | Uranus XX | Gladman, Holman, Kavelaars, Petit, Scholl [link] | ||
| Prospero | S/1999 U 3 | Uranus XVIII | Holman, Kavelaars, Gladman, Petit, Scholl [link] | ||
| 2000s | |||||
| Date | Name | Designation | Image | Planet/Number Designation | References/Notes |
| July 18-20, 2000 / October 6, 1999 | Callirrhoe | S/1999 J 1 | Jupiter XVII | Scotti, Spahr, McMillan, Larsen, Montani, Gleason, Gehrels [link] [link] | |
| August 7, 2000 | Ymir | S/2000 S 1 | Saturn XIX | Gladman [link] [link] | |
| Paaliaq | S/2000 S 2 | Saturn XX | Gladman [link] [link] | ||
| Kiviuq | S/2000 S 5 | Saturn XXIV | Gladman [link] [link] | ||
| September 23, 2000 | Siarnaq | S/2000 S 3 | Saturn XXIX | Gladman, Kavelaars [link] [link] | |
| Tarvos | S/2000 S 4 | Saturn XXI | Kavelaars, Gladman [link] [link] | ||
| Ijiraq | S/2000 S 6 | Saturn XXII | Kavelaars, Gladman [link] [link] | ||
| Thrymr | S/2000 S 7 | Saturn XXX | Gladman, Kavelaars [link] [link] | ||
| Skathi | S/2000 S 8 | Saturn XXVII | Kavelaars, Gladman [link] [link] | ||
| Mundilfari | S/2000 S 9 | Saturn XXV | Gladman, Kavelaars [link] [link] | ||
| Erriapo | S/2000 S 10 | Saturn XXVIII | Kavelaars, Gladman [link] [link] | ||
| Suttungr | S/2000 S 12 | Saturn XXIII | Gladman, Kavelaars [link] [link] | ||
| November 9, 2000 | Albiorix | S/2000 S 11 | Saturn XXVI | Holman, Spahr [link] [link] | |
| November 25 2000/ November 21, 2000 | Themisto* | S/2000 J 1 | Jupiter XVIII | Sheppard, Jewitt, Fernández, Magnier (Rediscovered) [link] [link] | |
| Date | Name | Designation | Image | Planet/Number Designation | References/Notes |
21st century
External links
- [City of Hudson's Natural Satellite Page]
- [Gazetteer of Planetary Nomenclature]
- [Scott Sheppard's Giant Planet Satellite Page]
- [JPL Natural Satellite Discovery Data]
- [When Did the asteroids Become Minor Planets?]
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