Venus

Venus
True colour image of Venus, as captured by MESSENGER. A cloud layer permanently obscures the surface.
Designations
Pronunciation/ˈvnəs/
Named after
Roman goddess of love (see goddess Venus)
AdjectivesVenusian /vɪˈnjziən, -ʒən/,[1] rarely Cytherean /sɪθəˈrən/[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 often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker and denser than Earth and any other rocky body in the Solar System. Its atmosphere is composed of mostly carbon dioxide (CO2), with a global sulfuric acid cloud cover and no liquid water. At the mean surface level the atmosphere reaches a temperature of 737 K (464 °C; 867 °F) and a pressure 92 times greater than Earth's at sea level, turning the lowest layer of the atmosphere into a supercritical fluid. Venus is the third brightest object in Earth's sky, after the Moon and the Sun,[21][22] and, like Mercury, appears always relatively close to the Sun, either as a "morning star" or an "evening star", resulting from orbiting closer (inferior) to the Sun than Earth.

The orbits of Venus and Earth make the two planets approach each other in synodic periods of 1.6 years. In the course of this Venus comes closer to Earth than any other planet, while on average Mercury stays closer to Earth (and any other planet) due to its more inferior orbit. For interplanetary flights Venus is a frequently taken and often energy and time saving waypoint, performing gravity assisted flybys. Venus has no moons and has a very slow retrograde rotation about its axis, a result of competing forces of solar tidal locking and differential heating of Venus's massive atmosphere. As a result a Venusian day is 116.75 Earth days long, about half a Venusian solar year, which is 224.7 Earth days long.

Venus has a weak magnetosphere, lacking an internal dynamo it is induced by the solar wind interacting with the atmosphere. Internally, Venus has a coremantle, and crust. Internal heat escapes through active volcanism,[23][24] resulting in resurfacing, instead of plate tectonics. Venus may have had liquid surface water early in its history with a habitable environment,[25][26] before a runaway greenhouse effect evaporated any water and turned Venus into its present state.[27][28][29] Conditions at the cloud layer of Venus have been identified as possibly favourable for life on Venus, with possible biomarkers having been found in 2020, which has spurred new research and missions to Venus.

Humans have observed Venus throughout history across the globe, and have featured it in fiction, mythology, astrology and astronomy, acquiring particular importance in many cultures. With telescopes the phases of Venus became discernable and were soon by 1613 presented as decisive evidence disproving the then dominant geocentric model and supporting the heliocentric model. Venus was for the first time visited in 1961, by Venera 1 flying past it, achieving the first interplanetary flight. The first data from Venus was returned with the second interplanetary flight, in 1962 by Mariner 2. In 1967 the first interplanetary impactor (Venera 4) and in 1970 lander (Venera 7) reached Venus. The returned data revealed the strong greenhouse effect of the CO2 in its atmosphere, which fueled concerns about increasing CO2 in Earth's atmosphere, driving global warming and climate change.[30] As of 2025 there is one active mission to Venus, returning in 2030 (Solar Orbiter), and the next mission is planned to launch in 2026 (Venus Life Finder).

  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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  8. ^ a b Cite error: The named reference Seidelmann2007 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Konopliv1999 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference NASA_2015 was invoked but never defined (see the help page).
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  12. ^ Cite error: The named reference Margot_et_al_2021 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference iauwg_ccrsps2000 was invoked but never defined (see the help page).
  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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  16. ^ Cite error: The named reference Haus_et_al was invoked but never defined (see the help page).
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  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.
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  22. ^ Cite error: The named reference Walker_2017 was invoked but never defined (see the help page).
  23. ^ 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.
  24. ^ 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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  26. ^ Cite error: The named reference NA-20231026 was invoked but never defined (see the help page).
  27. ^ Cite error: The named reference Jakosky was invoked but never defined (see the help page).
  28. ^ Cite error: The named reference Hashimoto_et_al_2008 was invoked but never defined (see the help page).
  29. ^ Cite error: The named reference Shiga_2007 was invoked but never defined (see the help page).
  30. ^ Cite error: The named reference Newitz 2013 was invoked but never defined (see the help page).

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