page_title: History of Mars observation
section_title: Orbital models
hierarchical_section_title: History of Mars observation / Orbital models
caption_attribution_description: From Petrus Apianus&#59; Gemma Frisius&#32;(1539)&#32;Petri Apiani cosmographia, per Gemmam Phrysium, apud Louanienses medicum ac mathematicum insignem, restituta: additis de adem re ipsius Gemmae Phry. libellis, ut sequens pagina docet, Antwerp&#58; In pingui gallina Arnoldo Berckma[n]no [Arnold Birckmann], OCLC 1113627241. Schema huius præmiʃʃæ diuiʃionis Sphærarum. COELVM EMPIREVM HABITACVLVM DEI ET OMNIVM ELECTORVM Ⅰ0 &#160; ♌ &#166; Decimŭm Cœlŭm ♋ &#166; Primŭ Mobile ♊ &#166; &#160; ♉ &#166; &#160; ♈ &#166; &#160; ♓ &#166; &#160; ♒ &#166; &#160; ♑ &#166; &#160; ♐ &#166; &#160; ♏ &#166; &#160; ♎ &#166; &#160; ♍ &#166; 9 &#160; ♋ &#166; Nonŭ Cœlŭm ♊ &#166; Criʃtallinŭm ♉ &#166; &#160; ♈ &#166; ⊕ &#160; ♓ &#166; &#160; ♒ &#166; &#160; ♑ &#166; &#160; ♐ &#166; &#160; ♏ &#166; &#160; ♎ &#166;⊕ &#160; ♍ &#166; &#160; ♌ &#166; 8 ••••••★ ♋ &#166; (•) Octaŭum •• ♊ &#166; (•) Firmamentŭ • ♉ • &#166; •••••• ♈ &#166; ••★••★••• ♓ &#166; •••★• ♒ • &#166; ••••••••• ♑ &#166; •••★ ♐ &#166; ••••••• ♏ &#166; ★•★ ♎ &#166; ••••••• ♍ &#166; ••★•••• ♌ &#166; 7 COELÛ &#160; ♃ SATVRNI &#160; ★ 6 ♄ IOVIS &#160; ★ 5 ♂ MARTIS &#160; ★ 4 ☉ SOLIS &#160; ☼ 3 ♀VENERIS &#160; ★ Z ☿ MERCVRII &#160; ★ Ⅰ ☾ LVNÆ &#160; ◯ &#160; ☽ &#160; ◯ (•) Star aligned with following word; only two sizes of stars are used, relative positions ignored English: The scheme of the aforementioned division of spheres. · The empyrean (fiery) heaven, dwelling of God and of all the selected · 10 Tenth heaven, first cause · 9 Ninth heaven, crystalline · 8 Eighth heaven of the firmament · 7 Heaven of Saturn · 6 Jupiter · 5 Mars · 4 Sun · 3 Venus · 2 Mercury · 1 Moon Latina: Schema huius praemissae divisionis sphaerarum. · Coelum empireum habitaculum dei et omnium electorum · 10 Decimum coelum primu mobile · 9 Nonu coelum cristallinum · 8 Octavum [coelum] firmamentu · 7 Coelu saturni · 6 [Coelu] Iovis · 5 [Coelu] Martis · 4 [Coelu] Solis · 3 [Coelu] Veneris · 2 [Coelu] Mercurii · 1 [Coelu] Lunae Compare to: Sacrobosco's De sphaera mundi
context_page_description: The history of Mars observation is about the recorded history of observation of the planet Mars. Some of the early records of Mars' observation date back to the era of the ancient Egyptian astronomers in the 2nd millennium BCE. Chinese records about the motions of Mars appeared before the founding of the Zhou Dynasty. Detailed observations of the position of Mars were made by Babylonian astronomers who developed arithmetic techniques to predict the future position of the planet. The ancient Greek philosophers and Hellenistic astronomers developed a geocentric model to explain the planet's motions. Measurements of Mars' angular diameter can be found in ancient Greek and Indian texts. In the 16th century, Nicolaus Copernicus proposed a heliocentric model for the Solar System in which the planets follow circular orbits about the Sun. This was revised by Johannes Kepler, yielding an elliptic orbit for Mars that more accurately fitted the observational data.
  The first telescopic observation of Mars was by Galileo Galilei in 1610. Within a century, astronomers discovered distinct albedo features on the planet, including the dark patch Syrtis Major Planum and polar ice caps.
context_section_description: The Greeks used the word planēton to refer to the seven celestial bodies that moved with respect to the background stars and they held a geocentric view that these bodies moved about the Earth. In his work, The Republic (X.616E–617B), the Greek philosopher Plato provided the oldest known statement defining the order of the planets in Greek astronomical tradition. His list, in order of the nearest to the most distant from the Earth, was as follows: the Moon, Sun, Venus, Mercury, Mars, Jupiter, Saturn, and the fixed stars. In his dialogue Timaeus, Plato proposed that the progression of these objects across the skies depended on their distance, so that the most distant object moved the slowest.
  Aristotle, a student of Plato, observed an occultation of Mars by the Moon on 4 May 357 BCE. From this he concluded that Mars must lie further from the Earth than the Moon. He noted that other such occultations of stars and planets had been observed by the Egyptians and Babylonians. Aristotle used this observational evidence to support the Greek sequencing of the planets. His work De Caelo presented a model of the universe in which the Sun, Moon, and planets circle about the Earth at fixed distances. A more sophisticated version of the geocentric model was developed by the Greek astronomer Hipparchus when he proposed that Mars moved along a circular track called the epicycle that, in turn, orbited about the Earth along a larger circle called the deferent.
  In Roman Egypt during the 2nd century CE, Claudius Ptolemaeus (Ptolemy) attempted to address the problem of the orbital motion of Mars. Observations of Mars had shown that the planet appeared to move 40% faster on one side of its orbit than the other, in conflict with the Aristotelian model of uniform motion. Ptolemy modified the model of planetary motion by adding a point offset from the center of the planet's circular orbit about which the planet moves at a uniform rate of rotation. He proposed that the order of the planets, by increasing distance, was: the Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn, and the fixed stars. Ptolemy's model and his collective work on astronomy was presented in the multi-volume collection Almagest, which became the authoritative treatise on Western astronomy for the next fourteen centuries.
  In the 5th century CE, the Indian astronomical text Surya Siddhanta estimated the angular size of Mars as 2 arc-minutes (1/30 of a degree) and its distance to Earth as 10,433,000 km (1,296,600 yojana, where one yojana is equivalent to eight km in the Surya Siddhanta). From this the diameter of Mars is deduced to be 6,070 km (754.4 yojana), which has an error within 11% of the currently accepted value of 6,788 km. However, this estimate was based upon an inaccurate guess of the planet's angular size. The result may have been influenced by the work of Ptolemy, who listed a value of 1.57 arc-minutes. Both estimates are significantly larger than the value later obtained by telescope.
  In 1543, Nicolaus Copernicus published a heliocentric model in his work De revolutionibus orbium coelestium. This approach placed the Earth in an orbit around the Sun between the circular orbits of Venus and Mars. His model successfully explained why the planets Mars, Jupiter and Saturn were on the opposite side of the sky from the Sun whenever they were in the middle of their retrograde motions. Copernicus was able to sort the planets into their correct heliocentric order based solely on the period of their orbits about the Sun. His theory gradually gained acceptance among European astronomers, particularly after the publication of the Prutenic Tables by the German astronomer Erasmus Reinhold in 1551, which were computed using the Copernican model.
  On October 13, 1590, the German astronomer Michael Maestlin observed an occultation of Mars by Venus. One of his students, Johannes Kepler, quickly became an adherent to the Copernican system. After the completion of his education, Kepler became an assistant to the Danish nobleman and astronomer, Tycho Brahe. With access granted to Tycho's
caption: Geocentric model of the Universe.
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