Phases of Venus - wikipedia Phases of Venus Phases of Venus and evolution of its apparent diameter. The phases of the planet Venus are the different variations of lighting seen on the planet 's surface, similar to lunar phases. The first recorded observations of them were telescopic observations by Galileo Galilei in 1610. Although the extreme crescent phase of Venus has been observed with the naked eyes, there are no indisputable historical pre-telescopic records of it being observed. Contents 1 Observation 2 History 3 Naked eye observations 4 See also 5 Notes 6 References 7 External links Observation The phases of Venus result from the planet 's orbit around the Sun inside the Earth 's orbit giving the telescopic observer a sequence of progressive lighting similar in appearance to the moon 's phases. It presents a full image when it is on the opposite side of the Sun. It shows a quarter phase when it is at its maximum elongation from the Sun. Venus presents a thin crescent in telescopic views as it comes around to the near side between the Earth and the Sun and presents its new phase when it is between the Earth and the Sun. Since the planet has an atmosphere it can be seen at new in a telescope by the halo of light refracted around the planet. The full cycle from new to full to new again takes 584 days ( the time it takes Venus to overtake the Earth in its orbit ). The planet also changes in apparent size from 9.9 arc seconds at full ( superior conjunction ) up to a maximum of 68 arc seconds at new ( inferior conjunction ). Venus reaches its greatest magnitude of − 4.5 when it is an intermediate crescent shape at the point in its orbit, when it is 68 million km away from the Earth ( a combination of its closeness and the fact that it is 28 % illuminated ). History Diagram of the orbit of Venus in relationship to the Earth, observed by Galileo Galilei in 1610 The first known observations of the full planetary phases of Venus were by Galileo at the end of 1610 ( though not published until 1613 in the Letters on Sunspots ). Using a telescope, Galileo was able to observe Venus going through a full set of phases, something prohibited by the Ptolemaic system. ( The Ptolemaic system would never allow Venus to be fully lit from the perspective of the Earth, as this would require it to be on the far side of the sun, which is impossible if Venus 's orbit in its entirety is between the Earth and the sun, as the Ptolemaic system requires ). This observation essentially ruled out the Ptolemaic system, and was compatible only with the Copernican system and the Tychonic system and other geoheliocentric models such as the Capellan and Riccioli 's extended Capellan model. Naked Eye observations The extreme crescent phase of Venus can be seen without a telescope by those with exceptionally acute eyesight, at the limit of human perception. The angular resolution of the naked eye is about 1 minute of arc. The apparent disk of Venus ' extreme crescent measures between 60.2 and 66 seconds of arc, depending on the distance from Earth. Nevertheless it is possible for observers with extremely acute eyesight to see a crescent Venus under ideal atmospheric circumstances. There have been numerous reports stating such observations. The phases of Venus are alleged to have been seen in Mesopotamian times by priest - astronomers. Ishtar ( Venus ) is described in cuneiform text as having horns. However, other Mesopotamian deities were depicted with horns, so the phrase could have been simply a symbol of divinity. See also Solar System portal Aspects of Venus Ashen light Notes ^ Jump up to : Goines, David Lance ( October 18, 1995 ). `` INFERENTIAL EVIDENCE FOR THE PRE-TELESCOPIC SIGHTING OF THE CRESCENT VENUS ''. Retrieved 2010 - 08 - 11. Jump up ^ souledout.org - Venus Has Phases... Like the Moon Jump up ^ Galileo 's observations of the phases of Venus ( slide 4 ) Jump up ^ Williams, David R. ( April 15, 2005 ). `` Venus Fact Sheet ''. NASA. Retrieved 2007 - 10 - 12. References Campbell, William Wallace ( 1916 ). `` Is the Crescent Form of Venus Visible to the Naked Eye ? ''. Publications of the Astronomical Society of the Pacific. 28 : 85 -- 86. Bibcode : 1916PASP... 28... 85C. doi : 10.1086 / 122498. Reinhardt, Carl ( 1929 ). `` Notes and Queries : Phase of Venus seen with the Naked Eye ''. Journal of the Royal Astronomical Society of Canada. 23 : 48 -- 49. Bibcode : 1929JRASC... 23... 48C. Goines, David Lance ( 1992 ). `` Observer 's Notebook : Naked Eye Crescent of Venus ''. Sky & Telescope. 83. External links Observations and Theories of Planetary Motion The crescent Venus seen with the naked eye Owen Gingerich - Empirical proof and / or persuasion -- lecture on Galileo 's observation of the phases of Venus from a renowned historian of science YouTube animation of the phases of Venus predicted by the pure geocentric Ptolemaic model ( 1 ) YouTube animation of the phases of Venus predicted by the heliocentric model ( and implicitly also by the geo - heliocentric models such as the Tychonic ) ( 2 ) Venus Outline of Venus Geography General Arachnoid Atmosphere Dune fields Features Regions Regio Alpha Regio Asteria Regio Beta Regio Ovda Regio Terrae Aphrodite Terra Ishtar Terra Lada Terra Mountains and volcanoes Abeona Mons Akna Montes Anala Mons Artemis Corona Ba'het Corona Boala Corona Ciuacoatl Mons Fand Mons Fotla Corona Gula Mons Heng - O Corona Iaso Tholus Irnini Mons Jaszai Patera Maat Mons Maxwell Montes Nightingale Corona Onatah Corona Quetzalpetlatl Corona Pancake dome Renpet Mons Sacajawea Patera Sachs Patera Sapas Mons Santa Corona Scalloped margin dome Siddons Patera Sif Mons Skadi Mons Theia Mons Ushas Mons Zisa Corona List of coronae on Venus Plains and plateaus Guinevere Planitia Lakshmi Planum Sedna Planitia Canyons and valleys Aikhulu Chasma Artemis Chasma Baltis Vallis Dali Chasma Devana Chasma Diana Chasma Ganis Chasma Craters Addams Adivar Agnesi Alcott Ariadne Aurelia Balch Barton Buck Cleopatra Cunitz Danilova De Lalande Dickinson Goeppert - Mayer Golubkina Grimke Gregory Guilbert Isabella Jeanne Maria Celeste Mariko Mead Meitner Merit Ptah Mona Lisa Nanichi Riley Ruth Stefania Wanda Wheatley Yablochkina Other Geodynamics Geology Surface features Venus snow Venusquake Moons Neith ( hypothetical moon ) Astronomy General Aspects Orbit Phases Transits 1639 1769 1874 1882 2012 Asteroids Venus - crosser asteroid 2002 VE 68 Exploration Past Sputnik programme Sputnik 7 Venera program Venera 1 Sputnik 19 Sputnik 20 Sputnik 21 Kosmos 21 Venera 1964A Kosmos 27 Venera 2 Venera 3 Kosmos 96 Venera 4 Kosmos 167 Venera 5 Venera 6 Venera 7 Venera 8 Kosmos 482 Venera 9 Venera 10 Venera 11 Venera 12 Venera 13 Venera 14 Venera 15 Venera 16 Mariner program Mariner 1 Mariner 2 Mariner 5 Mariner 10 Zond program Zond 1 Pioneer Venus Pioneer Venus Orbiter / Pioneer 12 Pioneer Venus Multiprobe / Pioneer 13 Vega program Vega 1 Vega 2 Magellan Galileo Cassini -- Huygens IKAROS MESSENGER Shin'en Venus Express Current Akatsuki Planned BepiColombo Venera - D Proposed European Venus Explorer Mercury - P Venus In Situ Explorer VISAGE Indian Venusian orbiter mission Proposed manned Colonization Inspiration Mars ( flyby ) Terraforming Other Geological mapping of Venus Artificial objects on Venus Related Cytherean Fiction Hesperus Life Mythology Phosphorus Venusians Book Portal Galileo Galilei Scientific career Observational astronomy Galileo affair Galileo 's escapement Galilean invariance Galilean moons Galilean transformation Leaning Tower of Pisa experiment Phases of Venus Celatone Thermoscope Works The Assayer De Motu Antiquiora Dialogue Concerning the Two Chief World Systems `` Discourse on the Tides '' `` Letter to the Grand Duchess Christina '' Sidereus Nuncius Two New Sciences Family Vincenzo Galilei ( father ) Michelagnolo Galilei ( brother ) Vincenzo Gamba ( son ) Maria Celeste ( daughter ) Marina Gamba ( mistress ) Related `` And yet it moves '' Villa Il Gioiello Galileo 's paradox Sector Museo Galileo Galileo 's telescopes Tribune of Galileo In popular culture Life of Galileo ( 1943 play ) Lamp At Midnight ( 1947 play ) Galileo ( 1968 film ) Galileo ( 1975 film ) Starry Messenger ( 1996 book ) Galileo 's Daughter : A Historical Memoir of Science, Faith, and Love ( 1999 book ) Galileo Galilei ( 2002 opera ) Galileo 's Dream ( 2009 novel ) Retrieved from `` https://en.wikipedia.org/w/index.php?title=Phases_of_Venus&oldid=824454853 '' Categories : Observational astronomy Venus Hidden categories : Articles with inconsistent citation formats Talk Contents About Wikipedia Français Hrvatski Italiano Norsk Português Русский Српски / srpski 中文 Edit links This page was last edited on 7 February 2018, at 13 : 02. 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Question: venus full phase occurs when venus is at
Answer: on the opposite side of the Sun