Venus

Venus is the second planet from the Sun.^[3] Venus is the only planet in the Solar System that has a day longer than a year. The year length of Venus is 225 Earth days. The day length of Venus is 243 Earth days.^[3]

Venus

A real-colour image taken by Mariner 10 processed from two filters, the surface is obscured by thick sulfuric acid (H2SO4) clouds
Designations
Pronunciation	/ˈviːnəs/ (listen)
Adjectives	Venusian or (rarely) Cytherean, Venerean
Orbital characteristics
Epoch J2000
Aphelion	0.728213 AU 108,939,000 km
Perihelion	0.718440 AU 107,477,000 km
Semi-major axis	0.723332 AU 108,208,000 km
Eccentricity	0.006772
Orbital period	224.701 d 0.615198 yr 1.92 Venus solar day
Synodic period	583.92 days
Average orbital speed	35.02 km/s
Mean anomaly	50.115°
Inclination	3.39458° to ecliptic 3.86° to Sun's equator 2.19° to invariable plane
Longitude of ascending node	76.680°
Argument of perihelion	54.884°
Satellites	None
Physical characteristics
Mean radius	6,051.8±1.0 km 0.9499 Earths
Flattening	0
Surface area	4.6023×108 km2 0.902 Earths
Volume	9.2843×1011 km3 0.866 Earths
Mass	4.8675×1024 kg 0.815 Earths
Mean density	5.243 g/cm3
Surface gravity	8.87 m/s2 0.904 g
Escape velocity	10.36 km/s (6.44 mi/s)[2]
Sidereal rotation period	−243.025 d (retrograde)
Equatorial rotation velocity	6.52 km/h (1.81 m/s)
Axial tilt	2.64° (for retrograde rotation) 177.36° (to orbit)[note 1]
North pole right ascension	18h 11m 2s 272.76°
North pole declination	67.16°
Albedo	0.689 (geometric) 0.76 (Bond)
Surface temp. min mean max Kelvin 737 K Celsius 462 °C Fahrenheit 864 °F
Apparent magnitude	−4.92 to −2.98
Angular diameter	9.7″–66.0″
Atmosphere
Surface pressure	92 bar (9.2 MPa)
Composition by volume	96.5% carbon dioxide 3.5% nitrogen 0.015% sulfur dioxide 0.007% argon 0.002% water vapour 0.0017% carbon monoxide 0.0012% helium 0.0007% neon trace carbonyl sulfide trace hydrogen chloride trace hydrogen fluoride
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 southern hemisphere and makes the axial tilt 177.36°.

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

Overview

Venus is a terrestrial planet because it has a solid, rocky surface like other planets in the inner Solar System. Astronomers have known Venus for thousands of years. The ancient Romans named it after their goddess Venus, goddess of love and beauty.^[3]

Venus is the brightest thing in the night sky except for the Moon. It is sometimes called the morning star or the evening star as at some elongations it is easily seen just before the Sun comes up in the morning. At other times, it can be seen just after the sun goes down in the evening. Venus comes closer to the Earth than any other planet does.

Composition

Venus is sometimes called the sister planet of Earth as they are quite similar in size and gravity. In other ways the planets are very different. Venus' atmosphere is mostly carbon dioxide (CO₂) with clouds of sulphuric acid (H₂SO₄).^[4] H₂SO₄ is a chemical that is poisonous to life. For this it is sometimes known as the Earth's "evil twin".^[5][6]

The thick atmosphere makes it hard to see the surface. Until the late twentieth century many thought there might be life there. The pressure on Venus' surface is 92 times that of Earth. Venus is one of only two planets in the Solar System (the other being Mercury) that has no moons. Venus spins very slowly on its axis and it spins in the opposite direction to the other planets.

Physical properties

Radar view of the surface of Venus (Magellan spacecraft)

Venus is a terrestrial planet so, like the Earth, its surface is made of rock. Venus is much hotter than Earth. All the carbon dioxide in the atmosphere acts like a blanket, trapping heat from the Sun. This effect is called the greenhouse effect and it is very strong on Venus. This makes the surface of Venus the hottest of any planet's surface in the Solar System with an estimated average temperature of 480 °C (896.0 °F).^[7][8] This is hot enough to melt lead or zinc.

Geography

Venus has no oceans because it is much too hot for water. Venus' surface is a dry desert. Because of the clouds, only radar can map the surface. It is about 80% smooth, rocky plains, made mostly of basalt. Two higher areas called continents make up the north and south of the planet. The north is called Ishtar Terra and the south is called Aphrodite Terra. They are named after the Babylonian and Greek goddesses of love.^[9]

The surface of Venus looks like it has been shaped by volcanic activity. Venus has a lot of volcanoes.^[10] The surface of Venus is estimated to be 300–600 million years old.^[10][11]

Unlike Earth or Mars, Venus does not have defined highlands or lowlands, and it does not have tectonic plates.

Atmosphere

Venus' atmosphere is mostly carbon dioxide and nitrogen gas with clouds of sulphuric acid. Because the atmosphere is so thick or dense the pressure is very high. The pressure is 92 times the pressure on Earth, enough to crush many things.

It is impossible to see the planet's surface from space as the thick cloud layer reflects 60% of the light that hits it. The only way scientists are able to see it is by using infrared and ultraviolet cameras and radar.

Scientists believe that billions of years ago, the atmosphere of Venus could have been like Earth's atmosphere. There may have been lots of water on the surface of Venus. But after 600 million to several billion years, the evaporation of the water put greenhouse gases into its atmosphere.^[12]

Magnetic field

In 1967, Venera 4 found that the magnetic field of Venus was much weaker than that of Earth. This magnetic field is induced by an interaction between the ionosphere and the solar wind. Venus' magnetosphere is not strong enough to protect the atmosphere from cosmic rays.^[13]

Transit of Venus

Main article: Transit of Venus

Venus can sometimes be seen passing between the Sun and Earth. Venus looks like a black dot when seen through a special telescope. These passages are called "transits". These "transits" happen in pairs eight years apart. Then it is more than a hundred years to the next pair.

Orbit and rotation

Main article: Orbit of Venus

Orbit of Venus compared to the orbit of the Earth

Venus orbits the Sun at an average distance of about 108 million km (68~ million mi). It completes an orbit every 224.7 days.^[14] The rotation of Venus is slow. A Venusian sidereal day is longer than a Venusian year.

List of satellites sent to Venus

Many man-made satellites have been sent to Venus to study it. They are:

Mariner

This section is transcluded from List of satellites sent to Venus. (edit | history)

Name	Launch Date	Country(s)	Date of Arrival at Venus	Date of Last Radio Signal	Did It Work as Planned?	Source(s)
Mariner 1	July 22, 1962	United States	Never happened because of launch failure	July 22, 1962	No	[15]
Mariner 2	August 27, 1962	United States	December 14, 1962	Janaury 3, 1963	Yes	[16][10]
Mariner 5	June 14, 1967	United States	June 19, 1967	October 14, 1968	Yes	[17][18]
Mariner 10	November 3, 1973	United States	February 5, 1974	March 24, 1975	Yes	[19][20]

Venera

This section is transcluded from List of satellites sent to Venus. (edit | history)

Name	Launch Date	Country(s)	Date of Arrival at Venus	Date of Last Radio Signal (lander/impactor)	Date of Last Radio Signal (orbiter/fly-by craft/kickstage)	Did It Work as Planned?	Source(s)
Sputnik 7[a]	February 4, 1961	Soviet Union	Never happened because of failure to leave Low Earth orbit	No lander[b]	February 26, 1961	No	[10]
Sputnik 19	August 25, 1962	Soviet Union	Never happened because of failure to leave Low Earth orbit	No lander	August 28, 1962	No	[10]
Venera 1	February 12, 1961	Soviet Union	May 19, 1961	No lander	February 17, 1961	No	[21]
Venera 2	November 12, 1965	Soviet Union	February 27, 1966	No lander	February 1966	No	[22][23]
Venera 3	November 16, 1965	Soviet Union	March 1, 1966	February 16, 1966	February 16, 1966	No	[24][25]
Venera 4	June 12, 1967	Soviet Union	October 18, 1967	No lander	October 18, 1967	Yes	[26]
Venera 5	January 5, 1969	Soviet Union	May 16, 1969	May 16, 1969	May 16, 1969	Yes	[27]
Venera 6	January 10, 1969	Soviet Union	May 17, 1969	May 17, 1969	May 17, 1969	Yes	[28]
Venera 7	August 17, 1970	Soviet Union	December 15, 1970	December 15, 1970	December 15, 1970	Landed but rolled and returned very little data	[29]
Venera 8	March 27, 1972	Soviet Union	July 22, 1972	July 22, 1972	July 22, 1972	Yes	[30]
Venera 9	June 8, 1975	Soviet Union	October 22, 1975	October 22, 1975	March 22, 1976	Yes	[31]
Venera 10	June 14, 1975	Soviet Union	October 25, 1975	October 25, 1975	June 1976		[32][10]
Venera 11	September 9, 1978	Soviet Union	December 25, 1978	December 25, 1978	February 1980	Yes, small issues with the some of the tools on the mission	[33][34]
Venera 12	September 14, 1978	Soviet Union	December 21, 1978	December 21, 1978	December 21, 1978	Yes, small issues with the some of the tools on the mission	[35]
Venera 13	October 30, 1981	Soviet Union	March 1, 1982	March 1, 1982	April 25, 1983	Yes	[36]
Venera 14	November 4, 1981	Soviet Union	March 5, 1982	March 5, 1982	April 9, 1983	Yes	[37][10]
Venera 15	June 2, 1983	Soviet Union	October 1983	No lander	July 1984	Yes	[38][3]
Venera 16	June 7, 1983	Soviet Union	October 1983	No lander	July 1984	Yes	[38][3]

Related pages

• List of planets

Notes

1. Venera was a name only given to Venus missions that left Low Earth orbit. Missions that failed to do so where given either Sputnik or Kosmos names instead. They are still included in the Venera list, as that was their intended name.
2. No lander means that no lander or impactor ever went into the Venusian atmosphere with the goal of landing or impacting. Launch failures, or satellites that failed to reach Venus, do not count.