Venus

This article is about the planet. For the deity, see Venus (mythology). For other uses, see Venus (disambiguation).

Venus
True colour image of Venus, as captured by MESSENGER. A cloud layer permanently obscures the surface.
Designations
Pronunciation/ˈviːnəs/ ⓘ
Named after
Roman goddess of love (see goddess Venus)
AdjectivesVenusian /vɪˈnjuːziən, -ʒən/,[1] rarely Cytherean /sɪθəˈriːən/[2] or Venerean / Venerian /vɪˈnɪəriən/[3]
Symbol♀
Orbital characteristics[4][5]
Epoch J2000
Aphelion0.728213 AU (108.94 million km)
Perihelion0.718440 AU (107.48 million km)
0.723332 AU (108.21 million km)
Eccentricity0.006772[6]
583.92 days[4]
35.02 km/s
50.115°
Inclination
76.680°[6]
54.884°
SatellitesNone
Physical characteristics
  • 6,051.8±1.0 km[8]
  • 0.9499 Earths
Flattening0[8]
  • 4.6023×108 km2
  • 0.902 Earths
Volume
  • 9.2843×1011 km3
  • 0.857 Earths
Mass
  • 4.8675×1024 kg[9]
  • 0.815 Earths
Mean density
5.243 g/cm3
8.87 m/s2 (0.904 g0)
10.36 km/s (6.44 mi/s)[10]
−116.75 d (retrograde)[11]
1 Venus solar day
−243.0226 d (retrograde)[12]
Equatorial rotation velocity
1.81 m/s
2.64° (for retrograde rotation)
177.36° (to orbit)[4][note 1]
North pole right ascension
North pole declination
67.16° [14]
Albedo
Temperature232 K (−41 °C) (blackbody temperature)[17]
Surface temp. min mean max
Kelvin 737 K[4]
Celsius 464 °C
Fahrenheit 867 °F
Surface absorbed dose rate2.1×10−6 μGy/h[18]
Surface equivalent dose rate2.2×10−6 μSv/h
0.092–22 μSv/h at cloud level[18]
−4.92 to −2.98[19]
−4.4[20]
9.7″–66.0″[4]
Atmosphere[4]
Surface pressure
93 bar (9.3 MPa)
92 atm
Composition by volume
  1. ^ Defining the rotation as retrograde, as done by NASA space missions and the USGS, puts Ishtar Terra in the northern hemisphere and makes the axial tilt 2.64°. Following the right-hand rule for prograde rotation puts Ishtar Terra in the negative hemisphere and makes the axial tilt 177.36°.

Venus is the second planet from the Sun. It is a terrestrial planet and is the closest in mass and size to its orbital neighbour Earth. Venus has by far the densest atmosphere of the terrestrial planets, composed mostly of carbon dioxide with a thick, global sulfuric acid cloud cover. At the surface it has a mean temperature of 737 K (464 °C; 867 °F) and a pressure 92 times that of Earth's at sea level. These extreme conditions compress carbon dioxide into a supercritical state at Venus's surface.

Internally, Venus has a core, mantle, and crust. Venus lacks an internal dynamo, and its weakly induced magnetosphere is caused by atmospheric interactions with the solar wind. Internal heat escapes through active volcanism,[21][22] resulting in resurfacing instead of plate tectonics. Venus is one of two planets in the Solar System, the other being Mercury, that have no moons.[23] Conditions perhaps favourable for life on Venus have been identified at its cloud layers. Venus may have had liquid surface water early in its history with a habitable environment,[24][25] before a runaway greenhouse effect evaporated any water and turned Venus into its present state.[26][27][28]

The rotation of Venus has been slowed and turned against its orbital direction (retrograde) by the currents and drag of its atmosphere.[29] It takes 224.7 Earth days for Venus to complete an orbit around the Sun, and a Venusian solar year is just under two Venusian days long. The orbits of Venus and Earth are the closest between any two Solar System planets, approaching each other in synodic periods of 1.6 years. Venus and Earth have the lowest difference in gravitational potential of any pair of Solar System planets. This allows Venus to be the most accessible destination and a useful gravity assist waypoint for interplanetary flights from Earth.

Venus figures prominently in human culture and in the history of astronomy. Orbiting inferiorly (inside of Earth's orbit), it always appears close to the Sun in Earth's sky, as either a "morning star" or an "evening star". While this is also true for Mercury, Venus appears more prominent, since it is the third brightest object in Earth's sky after the Moon and the Sun.[30][31] In 1961, Venus became the target of the first interplanetary flight, Venera 1, followed by many essential interplanetary firsts, such as the first soft landing on another planet by Venera 7 in 1970. These probes demonstrated the extreme surface conditions, an insight that has informed predictions about global warming on Earth.[32] This finding ended the theories and then popular science fiction about Venus being a habitable or inhabited planet.

  1. ^ Cite error: The named reference Lexico_Venusian was invoked but never defined (see the help page).
  2. ^ "Cytherean". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  3. ^ "Venerean, Venerian". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  4. ^ a b c d e f g Cite error: The named reference fact was invoked but never defined (see the help page).
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  6. ^ a b Cite error: The named reference VSOP87 was invoked but never defined (see the help page).
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  14. ^ a b Archinal, B. A.; Acton, C. H.; A'Hearn, M. F.; Conrad, A.; Consolmagno, G. J.; Duxbury, T.; Hestroffer, D.; Hilton, J. L.; Kirk, R. L.; Klioner, S. A.; McCarthy, D.; Meech, K.; Oberst, J.; Ping, J.; Seidelmann, P. K. (2018). "Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2015". Celestial Mechanics and Dynamical Astronomy. 130 (3): 22. Bibcode:2018CeMDA.130...22A. doi:10.1007/s10569-017-9805-5. ISSN 0923-2958.
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  17. ^ Cite error: The named reference American Chemical Society 2013 was invoked but never defined (see the help page).
  18. ^ a b Cite error: The named reference radiation-levels was invoked but never defined (see the help page).
  19. ^ Cite error: The named reference Mallama_and_Hilton was invoked but never defined (see the help page).
  20. ^ "Encyclopedia – the brightest bodies". IMCCE. Archived from the original on 24 July 2023. Retrieved 29 May 2023.
  21. ^ Andrews, Roy George (27 May 2024). "Rivers of Lava on Venus Reveal a More Volcanically Active Planet - New software let scientists re-examine old radar images, providing some of the strongest evidence yet that volcanoes continue to reshape the hellish planet". The New York Times. Archived from the original on 28 May 2024. Retrieved 28 May 2024.
  22. ^ Sulcanese, Davide; Mitri, Giuseppe; Mastrogiuseppe, Marco (27 May 2024). "Evidence of ongoing volcanic activity on Venus revealed by Magellan radar". Nature Astronomy. 8 (8): 973–982. Bibcode:2024NatAs...8..973S. doi:10.1038/s41550-024-02272-1. ISSN 2397-3366. Archived from the original on 28 May 2024. Retrieved 28 May 2024.
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  29. ^ Kane, Stephen (22 April 2022). "Atmospheric dynamics of a near tidally locked Earth-sized planet". Nature Astronomy. 6 (4): 420–427. arXiv:2204.09696. Bibcode:2022NatAs...6..420K. doi:10.1038/s41550-022-01626-x.
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