Misplaced Pages

Martian canals: Difference between revisions

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.
Browse history interactively← Previous editContent deleted Content addedVisualWikitext
Revision as of 15:44, 23 April 2020 editDrobertpowell (talk | contribs)Extended confirmed users980 edits Added a detail.← Previous edit Latest revision as of 02:00, 8 December 2024 edit undoT g7 (talk | contribs)Extended confirmed users1,199 edits →Contemporary doubts and definitive debunk 
(84 intermediate revisions by 53 users not shown)
Line 1: Line 1:
{{short description|Late 19th-early 20th century idea of canals existing on Mars}} {{Short description|Erroneous idea of canals on Mars}}
{{More citations needed|date=September 2019}} {{More citations needed|date=September 2019}}
], showing canals snaking through the Martian landscape. At the time, the existence of the canals was still highly controversial as no close-up pictures of Mars had been taken (until ]'s flyby in 1965).]]
]
During the late 19th and early 20th centuries, it was erroneously believed that there were "'''canals'''" on the ] ]. These were a network of long straight lines in the equatorial regions from 60° north to 60° south latitude on Mars, observed by ]s using early low-resolution telescopes without photography. They were first described by the Italian astronomer ] during the ] of 1877, and confirmed by later observers. Schiaparelli called these ''canali'', which was translated into English as "canals". The Irish astronomer ] made some of the earliest drawings of straight-line features on Mars, although his drawings did not match Schiaparelli's. Around the turn of the century there was even speculation that they were engineering works, irrigation canals constructed by a civilization of intelligent aliens indigenous to Mars. By the early 20th century, improved astronomical observations revealed the "canals" to be an ], and modern high-resolution mapping of the Martian surface by spacecraft shows no such features. During the late 19th and early 20th centuries, it was erroneously believed that there were "]s" on the planet ]. These were a network of long straight lines in the equatorial regions from 60° north to 60° south latitude on Mars, observed by ]s using early telescopes without photography.


They were first described by the Italian astronomer ] during the ] of 1877, and attested to by later observers. Schiaparelli called these ''canali'' ("]"), which was mis-translated into English as "canals". The Irish astronomer ] made some of the earliest drawings of straight-line features on Mars, although his drawings did not match Schiaparelli's.
==History==
]
]
The ] word ''canale'' (plural ''canali'') can mean "canal", "channel", "duct" or "gully".<ref></ref> The first person to use the word ''canale'' in connection with Mars was ] in 1858, although he did not see any straight lines and applied the term to large features &mdash;for example, he used the name "Canale Atlantico" for what later came to be called ].


Around the turn of the century there was even speculation that they were engineering works, irrigation canals constructed by a civilization of intelligent aliens indigenous to Mars. By the early 20th century, improved astronomical observations revealed the "canals" to be an ], and modern high-resolution mapping of the Martian surface by spacecraft shows no such features.
It is not necessarily odd that the idea of Martian canals was so readily accepted by many.{{original research inline|date=September 2019}} At this time in the late 19th century, astronomical observations were made without photography. Astronomers had to stare for hours through their telescopes, waiting for a moment of ] when the image was clear, and then draw a picture of what they had seen. They saw some lighter or darker ]s (for instance Syrtis Major) and believed that they were seeing oceans and continents. They also believed that Mars had a relatively substantial atmosphere. They knew that the ] of Mars (the length of its day) was almost the same as Earth's, and they knew that Mars' ] was also almost the same as Earth's, which meant it had seasons in the astronomical and meteorological sense. They could also see Mars' polar ice caps shrinking and growing with these changing seasons. It was only when they interpreted changes in surface features as being due to the seasonal growth of plants that life was hypothesized by them (in fact, Martian ]s are responsible for some of this). By the late 1920s, however, it was known that Mars is very dry and has a very low atmospheric pressure.


== Supposed "discoveries" ==
In 1889, American astronomer ] reported that Schiaparelli's canal discovery of 1877 had been confirmed in 1881, though new canals had appeared where there had not been any before, prompting "very important and perplexing" questions as to their origin.<ref>Young, Charles A. "''A Textbook of General Astronomy''. 1889. Ginn and Co. Boston.</ref>
{{Expand section|1=details about Schiaparelli's observation and description|section=1|date=October 2020}}
]
The ] word ''canale'' (plural ''canali'') can mean "canal", "channel", "duct" or "gully".<ref></ref> The first person to use the word ''canale'' in connection with Mars was ] in 1858, although he did not see any straight lines and applied the term to large features&mdash;for example, he used the name "Canale Atlantico" for what later came to be called ]. The canals were named by Schiaparelli and others{{who|date=November 2022}} after both real and legendary rivers of various places on Earth, or the mythological underworld.


At this time in the late 19th century, astronomical observations were made without photography. Astronomers had to stare for hours through their telescopes, waiting for a moment of ] when the image was clear, and then draw a picture of what they had seen. Astronomers believed at the time that Mars had a relatively substantial atmosphere. They knew that the ] of Mars (the length of its day) was almost the same as Earth's, and they knew that Mars' ] was also almost the same as Earth's, which meant it had seasons in the astronomical and meteorological sense. They could also see Mars' polar ice caps shrinking and growing with these changing seasons. The similarities with Earth led them to interpret darker ]s (for instance Syrtis Major) on the lighter surface as oceans. By the late 1920s, however, it was known that Mars is very dry and has a very low atmospheric pressure.] to achieve a near perfect theoretical ]. However, due to ], it is extremely difficult to see finer details.]]In 1889, American astronomer ] reported that Schiaparelli's canal discovery of 1877 had been confirmed in 1881, though new canals had appeared where there had not been any before, prompting "very important and perplexing" questions as to their origin.<ref>{{cite book |last=Young |first=Charles A. |title=A Textbook of General Astronomy |year=1889 |publisher=Ginn and Co. |place=Boston, MA}}</ref>
During the favourable opposition of 1892, ] observed numerous small circular black spots occurring at every intersection or starting-point of the "canals". Many of these had been seen by Schiaparelli as larger dark patches, and were termed seas or lakes; but Pickering's observatory was at ], about 2400 meters above the sea, and with such atmospheric conditions as were, in his opinion, equal to a doubling of telescopic aperture. They were soon detected by other observers, especially by Lowell.

During the favourable opposition of 1892, ] observed numerous small circular black spots occurring at every intersection or starting-point of the "canals". Many of these had been seen by Schiaparelli as larger dark patches, and were termed ''seas'' or ''lakes''; but Pickering's observatory was at ], about 2400&nbsp;meters above the sea, and with such atmospheric conditions as were, in his opinion, equal to a doubling of telescopic aperture. They were soon detected by other observers, especially by Lowell.<ref name="Lane">{{cite book |last1=Lane |first1=K. Maria D. |title=Geographies of Mars: Seeing and Knowing the Red Planet |date=2011 |url=https://books.google.com/books?id=1uNo3Zzo15gC&q=martian+canals+pickering+1892 |publisher=University of Chicago Press, 2011 |isbn=978-0-226-47078-8 |access-date=5 May 2024}}</ref>


During the oppositions of 1892 and 1894, seasonal color changes were reported. As the polar snows melted the adjacent seas appeared to overflow and spread out as far as the tropics, and were often seen to assume a distinctly green colour. At this time (1894) it began to be doubted whether there were any seas at all on Mars. Under the best conditions, these supposed 'seas' were seen to lose all trace of uniformity, their appearance being that of a mountainous country, broken by ridges, rifts, and canyons, seen from a great elevation. These doubts soon became certainties, and it is now universally agreed that Mars possesses no permanent bodies of surface water. During the oppositions of 1892 and 1894, seasonal color changes were reported. As the polar snows melted the adjacent seas appeared to overflow and spread out as far as the tropics, and were often seen to assume a distinctly green colour. At this time (1894) it began to be doubted whether there were any seas at all on Mars. Under the best conditions, these supposed 'seas' were seen to lose all trace of uniformity, their appearance being that of a mountainous country, broken by ridges, rifts, and canyons, seen from a great elevation. These doubts soon became certainties, and it is now universally agreed that Mars possesses no permanent bodies of surface water.


===Interpretation as engineering works=== == Interpretation as engineering works ==
]
During the 1894 opposition, the idea that Schiaparelli's ''canali'' were really irrigation canals made by intelligent beings was first hinted at, and then adopted as the only intelligible explanation, by American astronomer ] and a few others. The visible seasonal melting of Mars polar icecaps fueled speculation that an advanced alien race indigenous to Mars built canals to transport the water to drier equatorial regions. Newspaper and magazine articles about Martian canals and "Martians" captured the public imagination. Lowell published his views in three books: ''Mars'' (1895), ''Mars and Its Canals'' (1906), and ''Mars As the Abode of Life'' (1908). He remained a strong proponent for the rest of his life of the idea that the canals were built for irrigation by an intelligent civilization,<ref name="NYT-20151001">{{cite news |last=Dunlap |first=David W. |title=Life on Mars? You Read It Here First. |url=https://www.nytimes.com/2015/09/30/insider/life-on-mars-you-read-it-here-first.html |date=October 1, 2015 |work=] |accessdate=October 1, 2015 }}</ref> going much further than Schiaparelli, who for his part considered much of the detail on Lowell's drawings to be imaginary. Some observers drew maps in which dozens if not hundreds of canals were shown with an elaborate nomenclature for all of them. Some observers saw a phenomenon they called "gemination", or doubling – two parallel canals. The late 19th century was a time of construction of giant infrastructure projects of all kinds, and particularly ] building. For instance, the ] was completed in 1869, and the abortive French attempt to build the ] began in 1880. It is understandable that 19th century people who accepted the idea of a Mars inhabited by a civilization might interpret the canal features as giant engineering works.{{original research inline|date=September 2019}}
The hypothesis that there was life on Mars originated from seasonal changes observed in surface features, which began to be interpreted as due to seasonal growth of plants (in fact, Martian ]s are responsible for some of this).


During the 1894 opposition, the idea that Schiaparelli's ''canali'' were really irrigation canals made by intelligent beings was first hinted at, and then adopted as the only intelligible explanation, by American astronomer ] and a few others. The visible seasonal melting of Mars polar icecaps fueled speculation that an advanced alien race indigenous to Mars built canals to transport the water to drier equatorial regions. Newspaper and magazine articles about Martian canals and "Martians" captured the public imagination. Lowell published his views in three books: ''Mars'' (1895), ''Mars and Its Canals'' (1906), and ''Mars As the Abode of Life'' (1908). He remained a strong proponent for the rest of his life of the idea that the canals were built for irrigation by an intelligent civilization,<ref name="NYT-20151001">{{cite news |last=Dunlap |first=David W. |title=Life on Mars? You read it here first |url=https://www.nytimes.com/2015/09/30/insider/life-on-mars-you-read-it-here-first.html |date=October 1, 2015 |newspaper=] |access-date=October 1, 2015 }}</ref> going much further than Schiaparelli, who for his part considered much of the detail on Lowell's drawings to be imaginary. Some observers drew maps in which dozens if not hundreds of canals were shown with an elaborate nomenclature for all of them. Some observers saw a phenomenon they called "gemination", or doubling – two parallel canals.<ref>{{Cite book |last=Martin |first=George R. R. |title=Old Mars |date=2012 |publisher=Titan Books |isbn=978-1-78329-949-2 |editor-last=Martin |editor-first=George R. R. |editor-link=George R. R. Martin |language=en |chapter=Introduction: Red Planet Blues |author-link=George R. R. Martin |editor-last2=Dozois |editor-first2=Gardner |editor-link2=Gardner Dozois |chapter-url=https://books.google.com/books?id=ACtmCgAAQBAJ&pg=PT6}}</ref><!-- The Martin source verifies some of the preceding text, but not all of it. -->
===Doubts===
Other observers disputed the notion of canals. The observer ] did not see them. In 1903, ] and ] conducted visual experiments using schoolboy volunteers that demonstrated how the canals could arise as an ].<ref>] and ] (1903) "Experiments as to the Actuality of the 'Canals' observed on Mars",</ref> This is because when a poor-quality telescope views many point-like features (e.g. sunspots or craters) they appear to join up to form lines.<ref name="chambers">{{Cite book|author = Chambers P.|title = Life on Mars; The Complete Story|place = London|publisher = Blandford|date = 1999|isbn = 0-7137-2747-0|url-access = registration|url = https://archive.org/details/lifeonmarscomple00cham}}</ref> Based on his own experiments, Lowell's assistant, ], was led to explain the observations in essentially psychological terms.<ref>{{cite magazine |last=Sharps |first=Matthew J. |date=November-December 2019 |title=Percival Lowell and the Canals of Mars, Part II: How to See Things That Aren't There |url=https://skepticalinquirer.org/2019/11/percival-lowell-and-the-canals-of-mars-part-ii-how-to-see-things-that-arent-there/ |magazine=] |publisher=] |archive-url=http://archive.is/WvIjf |archive-date=23 April 2020 |access-date=23 April 2020}}</ref> In 1907 the British naturalist ] published the book ''Is Mars Habitable?'' that severely criticized Lowell's claims. Wallace's analysis showed that the surface of Mars was almost certainly much colder than Lowell had estimated, and that the atmospheric pressure was too low for liquid water to exist on the surface; and he pointed out that several recent efforts to find evidence of water vapor in the Martian atmosphere with ] had failed. He concluded that complex life was impossible, let alone the planet-girding irrigation system claimed by Lowell.<ref>{{cite web|last=Wallace|first=Alfred|title=''Is Mars Habitable'' (S730: 1907)|url=http://www.wku.edu/~smithch/wallace/S730.htm|publisher=The Alfred Russel Wallace Page hosted by ]|accessdate=2007-05-13}}</ref> The influential observer ] used the 83-cm (32.6&nbsp;inch) aperture telescope at ] at the 1909 ] of Mars and saw no canals, the outstanding photos of Mars taken at the new Baillaud dome at the ] observatory also brought formal discredit to the Martian canals theory in 1909,<ref>] (2010) "The first Pic du Midi photographs of Mars, 1909" </ref> and the notion of canals began to fall out of favor. Around this time spectroscopic analysis also began to show that no water was present in the Martian atmosphere.<ref name="chambers"/> However, as of 1916 ] (editor of '']'' and later '']'') was still vigorously defending the Martian canals theory against skeptics.<ref>{{Cite news|url=https://fivethirtyeight.com/features/a-mistranslated-word-led-to-some-of-the-best-fake-news-of-the-20th-century/|title=A Mistranslated Word Led To Some Of The Best Fake News Of The 20th Century|last=Hickey|first=Walt|date=2017-03-21|work=FiveThirtyEight|access-date=2017-03-23|language=en-US}}</ref>


== Contemporary doubts and definitive debunk ==
===Spacecraft evidence===
] probe in 1965]]
{{multiple image
Other observers disputed the notion of canals. The influential observer ] used the 83&nbsp;cm (32.6&nbsp;inch) aperture telescope at ] during the 1909 ] of Mars and saw no canals, the outstanding photos of Mars taken at the new Baillaud dome at the ] observatory also brought formal discredit to the Martian canals theory in 1909,<ref>{{cite journal |last=Dollfus |first=A. |author-link=Audouin Dollfus |year=2010 |title=The first Pic du Midi photographs of Mars, 1909 |url=http://adsbit.harvard.edu//full/2010JBAA..120..240D/0000241.000.html |journal=Journal of the British Astronomical Association |type=abstract |volume=120 |page=240 |bibcode=2010JBAA..120..240D}}</ref> and the notion of canals began to fall out of favor. Around this time spectroscopic analysis also began to show that no water was present in the Martian atmosphere.<ref name="chambers">{{cite book |author=Chambers, P. |url=https://archive.org/details/lifeonmarscomple00cham |title=Life on Mars: The complete story |publisher=Blandford |year=1999 |isbn=0-7137-2747-0 |place=London, UK |url-access=registration}}</ref> However, as of 1916 ] (editor of '']'' and later '']'') was still vigorously defending the Martian canals theory against skeptics.<ref>{{Cite news |last=Hickey |first=Walt |date=2017-03-21 |title=A mistranslated word led to some of the best fake news of the 20th&nbsp;century |language=en-US |work=FiveThirtyEight |url=https://fivethirtyeight.com/features/a-mistranslated-word-led-to-some-of-the-best-fake-news-of-the-20th-century/ |access-date=2017-03-23}}</ref>
| align = right

| direction = horizontal
In 1907 the British naturalist ] published the book ''Is Mars Habitable?'' that severely criticized Lowell's claims. Wallace's analysis showed that the surface of Mars was almost certainly much colder than Lowell had estimated, and that the atmospheric pressure was too low for liquid water to exist on the surface. He also pointed out that several recent efforts to find evidence of water vapor in the Martian atmosphere with ] had failed. He concluded that complex life was impossible, let alone the planet-girding irrigation system claimed by Lowell.<ref>{{cite book |last=Wallace |first=Alfred |title=Is Mars Habitable? |id=S730 |year=1907 |url=https://people.wku.edu/charles.smith/wallace/S730.htm |department=The Alfred Russel Wallace web page |publisher=] |access-date=2007-05-13}}</ref>
| header =
| image1 = Mars - February 24 2007 (32687746426).jpg
| caption1 = Mars by Rosetta spacecraft on 24 February 2007.
| width1 = 200
| image2 = Mariner 4 craters.gif
| caption2 = Mars surface by Mariner 4 in 1965
| width2 = 218
| image3 =
| caption3 =
| width3 =
| footer =
}}


The arrival of the United States' ] spacecraft in 1965, which took pictures revealing ]s and a generally barren landscape, was the final nail in the coffin of the idea that Mars could be inhabited by higher forms of life, or that any canal features existed. A surface ] of 4.1 to 7.0 ] (410 to 700 ]), 0.4% to 0.7% of Earth atmospheric pressure, and daytime temperatures of −100 degrees ] were estimated. No ]<ref name="O'Gallagher"> The existence of Martian canals was still controversial even at the dawn of the ]. In 1965, the ''Sourcebook on the space sciences'' said that "Although there is no unanimous opinion concerning the existence of the canals, most astronomers would probably agree that there are apparently linear (or approximately linear) markings, perhaps 40 to 160 kilometers (25 to 100 miles) or more across and of considerable length."<ref>{{Cite book |last=Glasstone |first=Samuel |url=http://archive.org/details/sourcebookonspac0000unse |title=Sourcebook on the space sciences |date=1965 |publisher=Princeton, N.J., D. Van Nostrand Co |others=Internet Archive |page=705}}</ref> Later in the same year, the arrival of the United States' ] spacecraft debunked for good the idea that Mars could be inhabited by higher forms of life, or that any canal features existed. It took pictures revealing ]s and a generally barren Martian landscape, with a surface ] of 4.1 to 7.0&nbsp;] (410 to 700&nbsp;]), 0.4% to 0.7% of Earth atmospheric pressure, and daytime temperatures of −100 degrees ] were measured. No ],<ref name="O'Gallagher">
{{cite journal {{cite journal
| last1 = O'Gallagher | first1 = J.J.
| title = Search for Trapped Electrons and a Magnetic Moment at Mars by Mariner IV
| last2 = Simpson | first2 = J.A.
| last = O'Gallagher
| first = J.J.
|author2=Simpson, J.A.
| journal = Science |series=New Series
| volume = 149
| issue = 3689
| date = 1965-09-10 | date = 1965-09-10
| title = Search for trapped electrons and a magnetic moment at Mars by Mariner&nbsp;IV
| pages = 1233–1239
| journal = Science
| doi = 10.1126/science.149.3689.1233
| pmid = 17747452 | series = New Series
| volume = 149 | issue = 3689 | pages = 1233–1239
|bibcode = 1965Sci...149.1233O }}</ref><ref name="Smith">
| doi = 10.1126/science.149.3689.1233 | pmid = 17747452
|bibcode = 1965Sci...149.1233O | s2cid = 21249845
}}</ref><ref name="Smith">
{{cite journal {{cite journal
| last1 = Smith | first1 = Edward J.
| title = Magnetic Field Measurements Near Mars
| last = Smith | first = Edward J. | last2 = Davis | first2 = Leverett Jr.
| author2 = Davis Jr. | author3 = Leverett; Coleman Jr. | author4 = Paul J. | author5 = Jones, Douglas E. | last3 = Coleman | first3 = Paul J. Jr.
| journal = Science |series=New Series | last4 = Jones | first4 = Douglas E.
| volume = 149
| issue = 3689
| date = 1965-09-10 | date = 1965-09-10
| title = Magnetic field measurements near Mars
| pages = 1241–1242
| journal = Science
| doi = 10.1126/science.149.3689.1241
| pmid = 17747454 | series = New Series
| volume = 149 | issue = 3689 | pages = 1241–1242
|bibcode = 1965Sci...149.1241S }}</ref> or ]<ref name="Van Allen">
| doi = 10.1126/science.149.3689.1241 | pmid = 17747454
| bibcode = 1965Sci...149.1241S | s2cid = 43466009
}}
</ref> nor ]<ref name="Van Allen">
{{cite journal {{cite journal
| title = Absence of Martian Radiation Belts and Implications Thereof | title = Absence of Martian radiation belts and implications thereof
| last = Van Allen | last1 = van Allen | first1 = J.A.
| first = J.A. | last2 = Frank | first2 = L.A.
| author2 = Frank, L.A. | author3 = Krimigis, S.M. | author4 = Hills, H.K. | last3 = Krimigis | first3 = S.M.
| last4 = Hills | first4 = H.K.
| date = 1965-09-10
| journal = Science |series=New Series | journal = Science |series=New Series
| volume = 149 | volume = 149 | issue = 3689 | pages = 1228–1233
| doi = 10.1126/science.149.3689.1228 | pmid = 17747451
| issue = 3689
| bibcode = 1965Sci...149.1228V | s2cid = 29117648
| date = 1965-09-10
| hdl = 2060/19650024318 | hdl-access=free
| pages = 1228–1233
}}</ref> were detected.
| doi = 10.1126/science.149.3689.1228
| pmid = 17747451
|bibcode = 1965Sci...149.1228V | hdl = 2060/19650024318|hdl-access=free
}}</ref> were detected.


As early as 1903, ] and ] conducted visual experiments using schoolboy volunteers that demonstrated how the canals could arise as an ].<ref>{{cite journal |last1=Evans |first1=J.E. |author1-link=Joseph Edward Evans |last2=Maunder |first2=E.W. |author2-link=Edward Walter Maunder |year=1903 |title=Experiments as to the actuality of the 'canals' observed on Mars |url=http://adsabs.harvard.edu//full/seri/MNRAS/0063//0000488.000.html |journal=] |type=abstract |volume=63 |issue=8 |page=488 |bibcode=1903MNRAS..63..488E |doi=10.1093/mnras/63.8.488|doi-access=free }}</ref> This is because when a poor-quality telescope views many point-like features (e.g. sunspots or craters) they appear to join up to form lines.<ref name="chambers" /> Based on his own experiments, Lowell's assistant, ], was led to explain the observations in essentially psychological terms.<ref>{{cite magazine |last=Sharps |first=Matthew J. |date=November–December 2019 |title=Part&nbsp;II: How to see things that aren't there |url=https://skepticalinquirer.org/2019/11/percival-lowell-and-the-canals-of-mars-part-ii-how-to-see-things-that-arent-there/ |url-status=live |magazine=] |publisher=] |volume=43 |issue=6 |pages=48–51 |archive-url=https://archive.today/20200423152857/https://skepticalinquirer.org/2019/11/skeptical-activist-robert-lancaster-dead-at-sixty-one/ |archive-date=23 April 2020 |access-date=23 April 2020 |series=Percival Lowell and the canals of Mars}}</ref> In hindsight, ], a Mars imaging scientist from the 1960s to the 2000s, hypothesized that the "canals" were streaks of dust caused by wind on the ] side of mountains and craters.<ref>{{cite AV media |url=https://www.npr.org/templates/story/story.php?storyId=94802645 |title=Robots on Mars search and catalog red planet |medium=audio |publisher=] |at=supporting statement approx. 34{{sup|m}}00{{sup|s}} after start}}</ref> ] has been proposed to correspond to the Coprates canal.<ref>http://lifeng.lamost.org/courses/astrotoday/CHAISSON/NAV/FRAMESET/FRAME10/IDX10-04.HTM</ref><ref>http://crism.jhuapl.edu/science/geology/question.php</ref><ref>https://page-one.springer.com/pdf/preview/10.1007/978-0-387-75468-0_4</ref>
], a Mars imaging scientist from the 1960s to the 2000s, explains the "canals" as streaks of dust caused by wind on the leeward side of mountains and craters.<ref>. Audio recording, supporting statement is approx. 34:00 after start.</ref>


==In popular culture== ==In popular culture==


{{see|Mars in fiction}} {{Further|Mars in fiction#Canals}}


{{Quote|A ], a ], and a ], while all classic science-fiction devices, are all, in fact, based upon earlier misapprehensions by planetary scientists.|], 1978<ref name="sagan19780528">{{Cite news |url=https://www.nytimes.com/1978/05/28/archives/growing-up-with.html |title=Growing up with science fiction |last=Sagan |first=Carl |date=1978-05-28 |newspaper=] |access-date=2018-12-12 |page=SM7 |lang=en-US |issn=0362-4331}}</ref>}}Martian canals first appeared in fiction in the anonymously published 1883 novel '']''.<ref>{{Cite book |last=Crossley |first=Robert |title=] |date=2011-01-03 |publisher=Wesleyan University Press |isbn=978-0-8195-7105-2 |pages=90–91 |language=en |chapter=Mars and Utopia |chapter-url=https://books.google.com/books?id=v3TDEDfEPdEC&pg=PA90}}</ref> Following the popularization of the idea that they were artificial constructs by Lowell's books, they appeared in numerous works of fiction until the Mariner 4 flyby conclusively demonstrated that they did not exist.<ref>{{Cite encyclopedia |year=2021 |title=Mars |encyclopedia=] |url=http://www.sf-encyclopedia.com/entry/mars |access-date=2022-05-28 |editor-last=Clute |editor-first=John |editor-link=John Clute |edition=4th |author2-last=Stableford |author2-first=Brian M. |author3-last=Langford |author3-first=David |author1-last=Killheffer |editor3-link=Graham Sleight |editor3-first=Graham |editor3-last=Sleight |editor2-first=David |author1-first=Robert K. J. |author3-link=David Langford |author2-link=Brian Stableford |editor2-last=Langford |editor2-link=David Langford}}</ref><ref>{{Cite book |last=Stableford |first=Brian M. |title=] |date=2006 |publisher=Taylor & Francis |isbn=978-0-415-97460-8 |pages=281–284 |language=en |chapter=Mars |author-link=Brian Stableford |chapter-url=https://books.google.com/books?id=uefwmdROKTAC&pg=PA281}}</ref><ref>{{Cite encyclopedia |year=2020 |title=Lowell, Percival |encyclopedia=] |url=https://sf-encyclopedia.com/entry/lowell_percival |access-date=2022-05-28 |last=Westfahl |first=Gary |author1-link=Gary Westfahl |editor-last=Clute |editor-first=John |editor-link=John Clute |edition=4th |editor2-link=David Langford |editor3-link=Graham Sleight |editor3-first=Graham |editor3-last=Sleight |editor2-first=David |editor2-last=Langford}}</ref>
{{quote|A ], a ], and a canal‐infested Mars, while all classic science‐fiction devices, are all, in fact, based upon earlier misapprehensions by planetary scientists.|], 1978<ref name="sagan19780528">{{Cite news |url=https://www.nytimes.com/1978/05/28/archives/growing-up-with.html |title=Growing up with Science Fiction |last=Sagan |first=Carl |date=1978-05-28 |work=The New York Times |access-date=2018-12-12 |page=SM7 |language=en-US |issn=0362-4331}}</ref>}}


== See also ==
Although the concept of the canals had been available since Schiaparelli's 1877 description of them, early fictional descriptions of Mars omitted these features. They receive no mention, for instance, in ]' '']'' (1897), which describes a slowly drying Mars, covetous of Earth's resources, but one which still has dwindling oceans such as are depicted on Schiaparelli's maps. Later works of fiction, influenced by the works of Lowell, described an ever-more arid Mars, and the canals became a more prominent feature, though how they were explained varied widely from author to author.
*]'s ''Uranie'' (1889, published as ''Urania'' in English in 1890) include descriptions of life on Mars; "They have straightened and enlarged the watercourses and made them like canals, and have constructed a network of immense canals all over the continents. The continents themselves are not bristling all over with Alpine or Himalayan upheavals like those of the terrestrial globe, but are immense plains, crossed in all directions by canals, which connect all the seas with one another, and by streams made to resemble canals."
*]' '']'' (1898) repeatedly mentions Schiaparellian canals (which play a key part in the denouement of the story), but does not describe them in detail, apparently considering them simply irrigation canals comparable to those on Earth — ignoring the fact that, in that case, they could hardly be visible from Earth. Serviss' Mars also has lakes and oceans.
* ]'s '']'' (1900) describes the canals as the remnants of gulfs and straits "widened and deepened and lengthened by... Martian labour".
* ]'s inaugural dissertation for his medical degree, '']'' (1902), describes the recounts of a 15-year-old patient, a medium who encountered supernatural beings during seance: "she told us all the peculiarities of the star-dwellers:... the whole of Mars is covered with canals, the canals are all flat ditches, the water in them is very shallow. The excavating of the canals caused the Martians no particular trouble, as the soil there is lighter than on earth."<ref>{{cite book|last=Jung|first=C.G.|title=Psychiatric Studies 2nd Ed.|date=1970|publisher=Princeton University Press|location=New Jersey|isbn=0-691-09768-2|pages=34}}</ref>
* ]' influential '']'' (1912) describes an almost entirely desert Mars, with only one small body of liquid water on the surface (though swamps and forests appear in ]). The canals, or waterways as Burroughs calls them, are still irrigation works, but these are surrounded by wide cultivated tracts of farmland which make their visibility somewhat credible.
*]'s '']'' (1913) details the social, scientific, and political history of the construction of the Martian canals and the socio-economic ramifications the construction had on Martian society.
* ]'s ''Outlaws of Mars'' (1933) has multiple parallel canals, surrounded by walls and terraces, and describes the construction of the canals by Martian machines.
* In ]'s '']'' (1934) the lead character Jarvis crosses several canals: One is "a dry ditch about four hundred feet wide, and straight as a railroad on its own company map." Some canals have "mud cities" and vegetation beside them. One appears to be covered with what looks like a nice green lawn, but turns out to be hundreds of small creatures that move out of the way when approached. In the sequel '']'' (1934) it is discovered that the various races on Mars cooperatively maintain the canal system, driving water northward from the southern polar icecap.
* "Seeds of the Dusk" (1938) is a short story by ] about a far-future twilight race of humans and animals on earth that are threatened by a newcomer plant that can defend itself adaptively, even killing an attacker. As it propagates and links in long chains with others of its species, the linked chains of plants begin pumping water through their specially formed inner chambers. At the end it is made apparent that the spores of the plant had drifted to Earth from Mars, and it was beginning to form long canals on Earth as it had done on Mars.
* In ]' '']'' (1938), the "canals" (''handramit'' in Martian) are actually vast rifts in the surface of an almost airless, desert Mars, in which the only breathable atmosphere and water have collected where life is possible, with the rest of Mars being entirely dead. As depicted by Lewis, these were of artificial origin – a vast engineering project undertaken long ago by the Martians to save what was left of their planet, after Mars was attacked and devastated by the evil Guardian Angel of Earth (who, in Lewis' system of theological Science Fiction, is the same as ]).
* In the ] book ''Outlaw World'' (1946), it is stated that Mars is kept alive by the ancient canal system carrying water from its polar caps. The most tightly kept secret of the planet is that radium powered engines are required to keep the water flowing.
* ] gave two depictions of the Martian canals:
** In '']'' (1947), the blind poet Rhysling, composes "The Grand Canal", describing the beauty of Mars' main canal as he saw it when first arriving on Mars. Having later become blind, Rhysling does not realize that human colonists have proceeded in short order to heavily pollute the canals with industrial wastes, tear down half of the delicate beautiful structures at the canal side and convert the other half to industrial uses – with the remnant of the indigenous Martians helpless to stop them.
** In '']'' (1949), colonists use the frozen canals for travel and a seasonal migration (by iceboat during winter when the canals are frozen and by boat when the ice melts during the Martian summer). Teenagers Jim Marlowe and Frank Sutton set out to skate the thousands of miles to their homes on the frozen Martian canals when escaping the Lowell Academy boarding school.
* The 180,000 year old narrator of ]'s "]" (1949) mentions he was one of the people digging the canals.
* In ]'s '']'' (1950), the canals are artificial waterways stretching between stone banks, filled with blue water, or sometimes poetically described as full of "green liquors" or "lavender wine". Bradbury revisited the martian canals in 1967 in his short story "The Lost City of Mars".
* In ]'s '']'' (1952), the canals turn out to be a broad vine-like plant growing a vast distance across the planet's surface.
* In the ] radio production '']: The Red Planet'' (1954–1955), the canals are valleys filled with a plant life resembling giant ]s.
* In '']'' (1964) Kit Draper and Friday flee from the enemy aliens through the underground canals on their way to the polar ice cap.
* In ]'s '']'' (1990), humans arriving on Mars discover a networks of canals in very bad condition due to the long period since the original builders became extinct. Human colonists energetically renovate the canals and put them to renewed use, discover at the Grand Canal the colossal buried city of the original builders, excavate it and build a thriving human city all around it. The human city is named "Schiaparelli".
* The Mars of the ] ] '']'' (1988) is crisscrossed by artificial canals which support cities inhabited by the ancient civilization of the Canal Martians.
* The 1991 computer game ] features a plot based around Victorian expeditions to Mars. The Martian canals play a very prominent role as the main characters have to find a way to refill them using ice from the polar caps.
* ]'s science fiction chronicling of the ] of Mars in the ] (1993–1999) and ] (2012) features the creation of canals on Mars ("burned" into the land with magnified sunlight) with the ] maps as inspiration. "Thus a nineteenth-century fantasy forms the basis for the actual landscape."<ref>{{cite book|last=Robinson|first=Kim Stanley|title=2312|date=2012|publisher=Orbit|location=New York|isbn=978-0-316-19280-4|pages=554–555}}</ref>
* In ]'s 2008 '']'' alternate history novel Mars is terraformed and seeded with earth life including early humans, at some point in prehistory. The humans of Mars do indeed build a planet wide canal network due to their world's exceptional dryness, however it's left ambiguous whether or not these were what Lowell actually saw in the 19th century.
*]'s 2013 novel, ''Equilateral'', is based entirely on the supposed existence of "man"-made Martian canals and on the construction of a vast triangle in the Arabian desert in order to communicate with the Martian beings.
* ]'s "Lullaby" from the 2014 album Soused (with ]) contains the lyrics, "Tonight my assistant will hear the canals of Mars." The composition first appeared on ]'s 2000 album, Punishing Kiss.


* {{annotated link|Classical albedo features on Mars}}
==List of canals==
* {{annotated link|Face on Mars}}
{{Main|List of Martian canals}}
* {{annotated link|History of Mars observation}}
The canals were named, by Schiaparelli and others, after real and legendary rivers of various places on Earth or the mythological underworld.
* {{annotated link|Life on Mars}}

* {{annotated link|Lineae}}
==See also==
* {{annotated link|Outflow channel}}
* ]
* {{annotated link|Solis Lacus}}
* ]
* {{annotated link|Valley networks (Mars)}}
* ]
* ] * {{annotated link|Water on Mars}}
* ]
* ]
* ]
* ]
* ]


==References== ==References==
{{Reflist}} {{reflist|25em}}
* ] (1907) ''Is Mars habitable? A critical examination of Professor Percival Lowell's book "Mars and its canals", with an alternative explanation, by Alfred Russel Wallace, F.R.S., etc.'' London, Macmillan and co. * {{cite book |author-link=Alfred Russel Wallace |last=Wallace |first=A.R. |year=1907 |title=Is Mars Habitable? |quote=A critical examination of Professor Percival Lowell's book ''Mars and its Canals'', with an alternative explanation, by Alfred Russel Wallace, F.R.S., etc. |place=London, UK |publisher=Macmillan and Co.}}
* ] (1910) "Sur la nature des »canaux« de Mars", (in French) * {{cite journal |author-link=Eugene Antoniadi |last=Antoniadi |first=E.M. |title=Sur la nature des »canaux« de Mars |url=http://adsabs.harvard.edu//full/seri/AN.../0183//0000117.000.html |journal=AN |volume=183 |year=1910 |issue=221–222 |lang=Fr |type=abstract}}


==External links== ==External links==
{{commons category|Martian canals}}
* http://www.theguardians.com/space/orbitalmech/gm_emoi1.htm
* {{cite web |first=Vicki |last=Lynn |year=1999 |title=The Martian canals: A saga of Martians and mistakes |series=Exploring Mars |url=http://www.theguardians.com/space/orbitalmech/gm_emoi1.htm |website=theguardians.com}}
*
* {{cite magazine |url=http://www.erbzine.com/mag14/1414.html |title=Martian canals throughout the history |magazine=ERBzine (Edgar Rice Boroughs fan magazine) |volume=Centennium&nbsp;XV |issue=1414 |first=Den |last=Valdron |series=Exploring Barsoom}}
{{Mars}} {{Mars}}
{{Portal bar|Solar System}} {{Portal bar|Astronomy|Stars|Spaceflight|Outer space|Science}}

{{DEFAULTSORT:Martian Canal}} {{DEFAULTSORT:Martian Canal}}
] ]

Latest revision as of 02:00, 8 December 2024

Erroneous idea of canals on Mars
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.
Find sources: "Martian canals" – news · newspapers · books · scholar · JSTOR (September 2019) (Learn how and when to remove this message)
A 1962 map of Mars published by the U.S. Aeronautical Chart and Information Center, showing canals snaking through the Martian landscape. At the time, the existence of the canals was still highly controversial as no close-up pictures of Mars had been taken (until Mariner 4's flyby in 1965).

During the late 19th and early 20th centuries, it was erroneously believed that there were "canals" on the planet Mars. These were a network of long straight lines in the equatorial regions from 60° north to 60° south latitude on Mars, observed by astronomers using early telescopes without photography.

They were first described by the Italian astronomer Giovanni Schiaparelli during the opposition of 1877, and attested to by later observers. Schiaparelli called these canali ("channels"), which was mis-translated into English as "canals". The Irish astronomer Charles E. Burton made some of the earliest drawings of straight-line features on Mars, although his drawings did not match Schiaparelli's.

Around the turn of the century there was even speculation that they were engineering works, irrigation canals constructed by a civilization of intelligent aliens indigenous to Mars. By the early 20th century, improved astronomical observations revealed the "canals" to be an optical illusion, and modern high-resolution mapping of the Martian surface by spacecraft shows no such features.

Supposed "discoveries"

This section needs expansion with: details about Schiaparelli's observation and description. You can help by adding to it. (October 2020)
1877 map of Mars by Giovanni Schiaparelli

The Italian word canale (plural canali) can mean "canal", "channel", "duct" or "gully". The first person to use the word canale in connection with Mars was Angelo Secchi in 1858, although he did not see any straight lines and applied the term to large features—for example, he used the name "Canale Atlantico" for what later came to be called Syrtis Major Planum. The canals were named by Schiaparelli and others after both real and legendary rivers of various places on Earth, or the mythological underworld.

At this time in the late 19th century, astronomical observations were made without photography. Astronomers had to stare for hours through their telescopes, waiting for a moment of still air when the image was clear, and then draw a picture of what they had seen. Astronomers believed at the time that Mars had a relatively substantial atmosphere. They knew that the rotation period of Mars (the length of its day) was almost the same as Earth's, and they knew that Mars' axial tilt was also almost the same as Earth's, which meant it had seasons in the astronomical and meteorological sense. They could also see Mars' polar ice caps shrinking and growing with these changing seasons. The similarities with Earth led them to interpret darker albedo features (for instance Syrtis Major) on the lighter surface as oceans. By the late 1920s, however, it was known that Mars is very dry and has a very low atmospheric pressure.

This is a modern ground-based telescope picture of Mars which uses lucky imaging to achieve a near perfect theoretical resolution. However, due to astronomical seeing, it is extremely difficult to see finer details.

In 1889, American astronomer Charles A. Young reported that Schiaparelli's canal discovery of 1877 had been confirmed in 1881, though new canals had appeared where there had not been any before, prompting "very important and perplexing" questions as to their origin.

During the favourable opposition of 1892, W. H. Pickering observed numerous small circular black spots occurring at every intersection or starting-point of the "canals". Many of these had been seen by Schiaparelli as larger dark patches, and were termed seas or lakes; but Pickering's observatory was at Arequipa, Peru, about 2400 meters above the sea, and with such atmospheric conditions as were, in his opinion, equal to a doubling of telescopic aperture. They were soon detected by other observers, especially by Lowell.

During the oppositions of 1892 and 1894, seasonal color changes were reported. As the polar snows melted the adjacent seas appeared to overflow and spread out as far as the tropics, and were often seen to assume a distinctly green colour. At this time (1894) it began to be doubted whether there were any seas at all on Mars. Under the best conditions, these supposed 'seas' were seen to lose all trace of uniformity, their appearance being that of a mountainous country, broken by ridges, rifts, and canyons, seen from a great elevation. These doubts soon became certainties, and it is now universally agreed that Mars possesses no permanent bodies of surface water.

Interpretation as engineering works

Martian canals depicted by Percival Lowell

The hypothesis that there was life on Mars originated from seasonal changes observed in surface features, which began to be interpreted as due to seasonal growth of plants (in fact, Martian dust storms are responsible for some of this).

During the 1894 opposition, the idea that Schiaparelli's canali were really irrigation canals made by intelligent beings was first hinted at, and then adopted as the only intelligible explanation, by American astronomer Percival Lowell and a few others. The visible seasonal melting of Mars polar icecaps fueled speculation that an advanced alien race indigenous to Mars built canals to transport the water to drier equatorial regions. Newspaper and magazine articles about Martian canals and "Martians" captured the public imagination. Lowell published his views in three books: Mars (1895), Mars and Its Canals (1906), and Mars As the Abode of Life (1908). He remained a strong proponent for the rest of his life of the idea that the canals were built for irrigation by an intelligent civilization, going much further than Schiaparelli, who for his part considered much of the detail on Lowell's drawings to be imaginary. Some observers drew maps in which dozens if not hundreds of canals were shown with an elaborate nomenclature for all of them. Some observers saw a phenomenon they called "gemination", or doubling – two parallel canals.

Contemporary doubts and definitive debunk

Mars surface imaged by the Mariner 4 probe in 1965

Other observers disputed the notion of canals. The influential observer Eugène Antoniadi used the 83 cm (32.6 inch) aperture telescope at Meudon Observatory during the 1909 opposition of Mars and saw no canals, the outstanding photos of Mars taken at the new Baillaud dome at the Pic du Midi observatory also brought formal discredit to the Martian canals theory in 1909, and the notion of canals began to fall out of favor. Around this time spectroscopic analysis also began to show that no water was present in the Martian atmosphere. However, as of 1916 Waldemar Kaempffert (editor of Scientific American and later Popular Science Monthly) was still vigorously defending the Martian canals theory against skeptics.

In 1907 the British naturalist Alfred Russel Wallace published the book Is Mars Habitable? that severely criticized Lowell's claims. Wallace's analysis showed that the surface of Mars was almost certainly much colder than Lowell had estimated, and that the atmospheric pressure was too low for liquid water to exist on the surface. He also pointed out that several recent efforts to find evidence of water vapor in the Martian atmosphere with spectroscopic analysis had failed. He concluded that complex life was impossible, let alone the planet-girding irrigation system claimed by Lowell.

The existence of Martian canals was still controversial even at the dawn of the Space Race. In 1965, the Sourcebook on the space sciences said that "Although there is no unanimous opinion concerning the existence of the canals, most astronomers would probably agree that there are apparently linear (or approximately linear) markings, perhaps 40 to 160 kilometers (25 to 100 miles) or more across and of considerable length." Later in the same year, the arrival of the United States' Mariner 4 spacecraft debunked for good the idea that Mars could be inhabited by higher forms of life, or that any canal features existed. It took pictures revealing impact craters and a generally barren Martian landscape, with a surface atmospheric pressure of 4.1 to 7.0 millibars (410 to 700 pascals), 0.4% to 0.7% of Earth atmospheric pressure, and daytime temperatures of −100 degrees Celsius were measured. No magnetic field, nor radiation belts were detected.

As early as 1903, Joseph Edward Evans and Edward Maunder conducted visual experiments using schoolboy volunteers that demonstrated how the canals could arise as an optical illusion. This is because when a poor-quality telescope views many point-like features (e.g. sunspots or craters) they appear to join up to form lines. Based on his own experiments, Lowell's assistant, A. E. Douglass, was led to explain the observations in essentially psychological terms. In hindsight, William Kenneth Hartmann, a Mars imaging scientist from the 1960s to the 2000s, hypothesized that the "canals" were streaks of dust caused by wind on the leeward side of mountains and craters. Valles Marineris has been proposed to correspond to the Coprates canal.

In popular culture

Further information: Mars in fiction § Canals

A clement twilight zone on a synchronously rotating Mercury, a swamp-and-jungle Venus, and a canal-infested Mars, while all classic science-fiction devices, are all, in fact, based upon earlier misapprehensions by planetary scientists.

— Carl Sagan, 1978

Martian canals first appeared in fiction in the anonymously published 1883 novel Politics and Life in Mars. Following the popularization of the idea that they were artificial constructs by Lowell's books, they appeared in numerous works of fiction until the Mariner 4 flyby conclusively demonstrated that they did not exist.

See also

References

  1. WordReference.com
  2. Young, Charles A. (1889). A Textbook of General Astronomy. Boston, MA: Ginn and Co.
  3. Lane, K. Maria D. (2011). Geographies of Mars: Seeing and Knowing the Red Planet. University of Chicago Press, 2011. ISBN 978-0-226-47078-8. Retrieved 5 May 2024.
  4. Dunlap, David W. (October 1, 2015). "Life on Mars? You read it here first". The New York Times. Retrieved October 1, 2015.
  5. Martin, George R. R. (2012). "Introduction: Red Planet Blues". In Martin, George R. R.; Dozois, Gardner (eds.). Old Mars. Titan Books. ISBN 978-1-78329-949-2.
  6. Dollfus, A. (2010). "The first Pic du Midi photographs of Mars, 1909". Journal of the British Astronomical Association (abstract). 120: 240. Bibcode:2010JBAA..120..240D.
  7. ^ Chambers, P. (1999). Life on Mars: The complete story. London, UK: Blandford. ISBN 0-7137-2747-0.
  8. Hickey, Walt (2017-03-21). "A mistranslated word led to some of the best fake news of the 20th century". FiveThirtyEight. Retrieved 2017-03-23.
  9. Wallace, Alfred (1907). Is Mars Habitable?. The Alfred Russel Wallace web page. Western Kentucky University. S730. Retrieved 2007-05-13.
  10. Glasstone, Samuel (1965). Sourcebook on the space sciences. Internet Archive. Princeton, N.J., D. Van Nostrand Co. p. 705.
  11. O'Gallagher, J.J.; Simpson, J.A. (1965-09-10). "Search for trapped electrons and a magnetic moment at Mars by Mariner IV". Science. New Series. 149 (3689): 1233–1239. Bibcode:1965Sci...149.1233O. doi:10.1126/science.149.3689.1233. PMID 17747452. S2CID 21249845.
  12. Smith, Edward J.; Davis, Leverett Jr.; Coleman, Paul J. Jr.; Jones, Douglas E. (1965-09-10). "Magnetic field measurements near Mars". Science. New Series. 149 (3689): 1241–1242. Bibcode:1965Sci...149.1241S. doi:10.1126/science.149.3689.1241. PMID 17747454. S2CID 43466009.
  13. van Allen, J.A.; Frank, L.A.; Krimigis, S.M.; Hills, H.K. (1965-09-10). "Absence of Martian radiation belts and implications thereof". Science. New Series. 149 (3689): 1228–1233. Bibcode:1965Sci...149.1228V. doi:10.1126/science.149.3689.1228. hdl:2060/19650024318. PMID 17747451. S2CID 29117648.
  14. Evans, J.E.; Maunder, E.W. (1903). "Experiments as to the actuality of the 'canals' observed on Mars". Monthly Notices of the Royal Astronomical Society (abstract). 63 (8): 488. Bibcode:1903MNRAS..63..488E. doi:10.1093/mnras/63.8.488.
  15. Sharps, Matthew J. (November–December 2019). "Part II: How to see things that aren't there". Skeptical Inquirer. Percival Lowell and the canals of Mars. Vol. 43, no. 6. Center for Inquiry. pp. 48–51. Archived from the original on 23 April 2020. Retrieved 23 April 2020.
  16. Robots on Mars search and catalog red planet (audio). National Public Radio.
  17. http://lifeng.lamost.org/courses/astrotoday/CHAISSON/NAV/FRAMESET/FRAME10/IDX10-04.HTM
  18. http://crism.jhuapl.edu/science/geology/question.php
  19. https://page-one.springer.com/pdf/preview/10.1007/978-0-387-75468-0_4
  20. Sagan, Carl (1978-05-28). "Growing up with science fiction". The New York Times. p. SM7. ISSN 0362-4331. Retrieved 2018-12-12.
  21. Crossley, Robert (2011-01-03). "Mars and Utopia". Imagining Mars: A Literary History. Wesleyan University Press. pp. 90–91. ISBN 978-0-8195-7105-2.
  22. Killheffer, Robert K. J.; Stableford, Brian M.; Langford, David (2021). "Mars". In Clute, John; Langford, David; Sleight, Graham (eds.). The Encyclopedia of Science Fiction (4th ed.). Retrieved 2022-05-28.
  23. Stableford, Brian M. (2006). "Mars". Science Fact and Science Fiction: An Encyclopedia. Taylor & Francis. pp. 281–284. ISBN 978-0-415-97460-8.
  24. Westfahl, Gary (2020). "Lowell, Percival". In Clute, John; Langford, David; Sleight, Graham (eds.). The Encyclopedia of Science Fiction (4th ed.). Retrieved 2022-05-28.

External links

Mars
Outline of Mars
Geography
Atmosphere
Regions
Physical
features
Geology
History
Astronomy
Moons
Transits
Asteroids
Comets
General
Exploration
Concepts
Missions
Advocacy
Related
Portals: Categories: