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| | {{Planet | | {{Planet |
| − | | name=Venus | + | |image=Venus.jpg |
| − | | image=Transit2004.jpg
| + | |caption=Venus silhouetted against the Sun during one of the rare transits of Venus, 6/8/2004 |
| − | | caption=Venus silhouetted against the Sun during one of the rare transits of Venus, 6/8/2004 | + | |symbol=Venus symbol.svg |
| − | | symbol=Venus symbol.svg | + | |discname=Known to the ancients |
| − | | order=2 | + | |origname=Roman goddess<br>of love and beauty |
| − | | diameter=12,103.6 km | + | |primary=Sun |
| − | | mass=4.869×10<sup>24</sup> kg | + | |order=2 |
| − | | distance=0.723 AU | + | |periapsis=107,476,259 km (0.718 AU) |
| − | | day=243 earth days | + | |apoapsis=108,942,109 km (0.728 AU) |
| − | | year=225 earth days | + | |semimajor=108,208,930 km (0.723 AU) |
| − | | moons=None | + | |bode=0.7 AU |
| − | | composition=Rock | + | |eccentricity=0.0068 |
| − | | color=
| + | |sidereal=224.70069 da (0.615 a) |
| − | | albedo=0.65 | + | |synodic=583.92 da (1.599 a) |
| − | | date=
| + | |orbitspeed=35.02 km/s |
| − | | discname=Known to the ancients
| + | |inclination=3.39471° |
| − | | origname=Roman goddess
| + | |reference=the ecliptic |
| | + | |siderealday=-243.0187 da |
| | + | |rotatespeed=6.52 km/h |
| | + | |axialtilt=177.36° |
| | + | |mass=4.8685 * 10<sup>24</sup> kg (81.468% earth) |
| | + | |density=5250 kg/m³ |
| | + | |meanradius=6051.8 km |
| | + | |surfacegrav=8.87 m/s² (0.904 ''g'') |
| | + | |escapespeed=10.36 km/s |
| | + | |surfacearea=460,235,000 km² (90.229% earth) |
| | + | |meantemp=730 K |
| | + | |moons=None |
| | + | |composition=Rock |
| | + | |albedo=0.65 |
| | |} | | |} |
| | }} | | }} |
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| | When the planet is visible, it is the brightest, most conspicuous, and easiest to recognize of all the planets. | | When the planet is visible, it is the brightest, most conspicuous, and easiest to recognize of all the planets. |
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| − | When Venus is the "evening star," It shines brightly in the West in the hours after sunset. It is visible long before the sky is dark enough to see any other star, and when people "wish upon a star" very often they are actually wishing upon Venus. You can see it shining through a window in a lit room, just like the "wishing star" in the opening of Walt Disney's animated cartoon, ''Pinocchio. | + | == Evening and Morning Stars == |
| | + | When Venus is the "evening star," it shines brightly in the West in the hours after sunset. It is visible long before the sky is dark enough to see any other star, and when people "wish upon a star" very often they are actually wishing upon Venus. You can see it shining through a window in a lit room, just like the "wishing star" in the opening of Walt Disney's animated cartoon, ''Pinocchio. |
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| | Astronomy books sometimes claim that "planets do not twinkle." This is not quite true, but Venus in particular does shine with a steadier light than any star. When looking at Venus, it is quite possible to wonder whether one is looking at a plane, until one has watched for long enough to be sure that it is not moving (or, at least, not moving quickly enough to notice). | | Astronomy books sometimes claim that "planets do not twinkle." This is not quite true, but Venus in particular does shine with a steadier light than any star. When looking at Venus, it is quite possible to wonder whether one is looking at a plane, until one has watched for long enough to be sure that it is not moving (or, at least, not moving quickly enough to notice). |
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| | Through a small telescope—binoculars will not do, but any real astronomical telescope will—it is possible to see that Venus often does not appear round, but goes through phases like the Moon, depending on how the light of the Sun strikes it. | | Through a small telescope—binoculars will not do, but any real astronomical telescope will—it is possible to see that Venus often does not appear round, but goes through phases like the Moon, depending on how the light of the Sun strikes it. |
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| | + | == Transits of Venus == |
| | About every two years, Venus "catches up with" and passes the Earth as they both orbit the Sun. This is called a "conjunction" of Venus and the Earth. During a conjunction, Venus is almost directly between the Earth and the Sun. It would seem as if Venus could be seen silhouetted against the Sun on every conjunction, but in fact the orbits of the planets are slightly tilted with respect to each other, so at a conjunction Venus almost never lines up perfectly, but appears to pass above or below the Sun. Very rarely—at intervals of over a century—conjunction occurs at the point in the orbits where they are both in the same plane. When this occurs, a ''transit of Venus'' can be observed. Transits of Venus occur in pairs, eight years apart; then over a century passes before the next one. | | About every two years, Venus "catches up with" and passes the Earth as they both orbit the Sun. This is called a "conjunction" of Venus and the Earth. During a conjunction, Venus is almost directly between the Earth and the Sun. It would seem as if Venus could be seen silhouetted against the Sun on every conjunction, but in fact the orbits of the planets are slightly tilted with respect to each other, so at a conjunction Venus almost never lines up perfectly, but appears to pass above or below the Sun. Very rarely—at intervals of over a century—conjunction occurs at the point in the orbits where they are both in the same plane. When this occurs, a ''transit of Venus'' can be observed. Transits of Venus occur in pairs, eight years apart; then over a century passes before the next one. |
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| | One of the rare transits of Venus occurred on June 8, 2004; another will occur on June 6, 2012; then there will be no more until 2117, probably not within the lifetime of those reading this. A transit of Venus cannot be seen with the naked eye. Observing a transit of Venus requires '''great attention to eye safety''' and a telescope ''equipped with a safe sun filter'' or a special transit viewer. | | One of the rare transits of Venus occurred on June 8, 2004; another will occur on June 6, 2012; then there will be no more until 2117, probably not within the lifetime of those reading this. A transit of Venus cannot be seen with the naked eye. Observing a transit of Venus requires '''great attention to eye safety''' and a telescope ''equipped with a safe sun filter'' or a special transit viewer. |
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| − | The planet Venus is about the same size as the Earth. Before explorations made by spacecraft made it clear just how harsh conditions on Venus are, science-fiction writers used to speculate that the temperature and climate of Venus might be within the range of life as we know it on Earth. Many science-fiction stories have been set on Venus. [[C. S. Lewis]]' novel ''Perelandra'' which takes place on Venus, and is a retelling of the story of the [[Garden of Eden]]. | + | The planet Venus is about the same size as the Earth. Before explorations made by spacecraft made it clear just how harsh conditions on Venus are, science-fiction writers used to speculate that the temperature and climate of Venus might be within the range of life as we know it on Earth. |
| | + | |
| | + | == Theoretical considerations == |
| | + | # Venus possesses very few impact craters. Therefore, uniformitarian geologists regard Venus as geologically young (estimated apparent age 800 million Julian years). Attempts to explain this feature of Venus have been lacking, and the very slow surface winds and lack of water on Venus complicates the matter further. |
| | + | # Venus rotates retrograde to its orbit around the Sun. (Note the negative value for a Venusian sidereal day.) Nearly every other Solar System body rotates prograde. This presents a serious theoretical problem for the [[nebular hypothesis]] of the origin of the solar system. |
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| | + | ==In popular culture== |
| | + | Many science-fiction stories have been set on Venus. [[C. S. Lewis]]' novel ''Perelandra'' which takes place on Venus, and is a retelling of the story of the [[Garden of Eden]]. Other [[motion picture]] projects have speculated on the consequences of the importation of an [[extraterrestrial life|extraterrestrial creature or creatures]] from Venus to [[Earth]]. |
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| | ==External links== | | ==External links== |
| − | [[Image:Venus.jpg]] | + | [[Image:Transit2004.jpg]] |
| − | *[http://www.transitofvenus.org/ TransitofVenus.org], website about the upcoming 2012 transit | + | * [http://www.transitofvenus.org/ TransitofVenus.org], website about the upcoming 2012 transit |
| − | | + | * [http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Venus&Display=Facts NASA "Venus"] |
| | + | * [http://www.answersingenesis.org/creation/v23/i3/venus.asp Venus: Cauldon of Fire] |
| | + | * [http://www2.jpl.nasa.gov/magellan/ Magellan Project home page] |
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| | {{Solarsystem}} | | {{Solarsystem}} |
| − | [[Category:Planets]] [[Category:Astrology]]
| + | [[Category:Astrology]] |