|Exploring Your World, The Adventures of Geography. Washington, DC: National Geographic, 1989: 388.||"Venus, Period of Rotation, 243 days"||243 days|
|Grolier Encyclopedia of Knowledge. Danbury, CT: Grolier, 1991: 19-146.||"completing one rotation in 243 days"||243 days|
|Weissman, Paul. The Solar System and Its Place in the Galaxy. Encyclopedia of the Solar System. Figure 1.||"Venus, Rotation Period, 243.018 days"||243.018 days|
|Venne, Bill. The Atlas of the Solar System.Greenwich: Brompton, 1987: 33.||"Venus ground-based radar measurements showed that its rotation is about 240 days."||240 days|
|Engelbert, Phillis, Astronomy and Space. Detroit, MI: UXL, 1997: 3, 673.||"It takes Venus 243 earth days to complete one rotation."||243 days|
Venus is the second planet from the sun and the planet that is closest to earth. It is named for the Roman Goddess of love and beauty and has been thought of throughout history as one of the most beautiful objects in the sky. Venus is covered by clouds that move three times faster than hurricane winds. The atmospheric pressure of Venus is 97 times that of earth and no magnetic fields are found on Venus.
Venus spins retrograde (opposite) relative to the earth's movement. The period of rotation of Venus (a Venusian day) is longer the Venusian year by 18.3 days. Venus circles the sun every 224.7 earth days. Most of my sources stated that the Venusian day is 243 earth days long. The oldest source states that the rotation period of Venus is approximately 240 days long. This number is based on Venus ground-based radar measurements taken in the early and mid-1960s and is fairly accurate. A technical source stated that the period of rotation of Venus 243.018 earth days. This is the most recent and the most accurate measurement. This number is only slightly different than that provided in sources for laymen. The writers of the textbooks and encyclopedias may have had the accurate measurement but simply ignored the 0.018 days and gave an approximate period of rotation.
Jessica Brodkin -- 1999