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At the surface, it has a mean temperature of 464 Degrees Celcius and a pressure of 92 times that of the Earth 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 atmospheric interactions with the solar wind cause its weakly induced magnetosphere. Internal heat escapes through active volcanism, resulting in resurfacing instead of plate tectonics. Venus is one of two planets in the Solar System, the other being Mercury, with no moons. Conditions perhaps favorable 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 before a runaway greenhouse effect evaporated any water and turned Venus into its present state.
The currents and drag of Venus's atmosphere have slowed and turned the planet's rotation against its orbital direction (retrograde). It takes Venus 227.7 Earth days 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 fights from Earth.
Venus figures prominently in human culture and 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 Sun and the Moon. 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. This finding ended the theories and then popular science fiction about Venus being a habitable or inhabited planet.
Diameter: 12104 km
Venus is one of the four terrestrial planets in the Solar System, meaning that it is a rocky body like Earth. It is similar to Earth in size and mass and is often described as Earth's "sister" or "twin". Venus is close to spherical due to its slow rotation. Its mass is 81.5% of Earth's, making it the third-smallest planet in the Solar System. Conditions on the Venusian surface differ radically from those on Earth because its dense atmosphere is 96.5% carbon dioxide, with most of the remaining 3.5% being nitrogen. The surface pressure is 9.3 megapascals (93 bars), and the average surface temperature is 464 degrees Celsius, above the critical points of both major constituents and making the surface atmosphere a supercritical fluid out of mainly superficial carbon dioxide and some supercritical nitrogen.
Venus's surface was a mystery until the 20th century when space probes like the Venera missions (1975 and 1982) captured images showing a rocky, volcanic terrain. The 1990 Magellan mission provided detailed maps that revealed widespread volcanic plains covering 80% of the planet, with a few highland "continents", including Ishtar Terra (in the north) and Aphrodite Terra (south). These areas feature rugged landscapes with fractures and faults, suggesting past tectonic-like activity.
Evidence of active volcanism was observed as recently as 2024, with lava flows detected on Venus's shield volcanoes. The surface shows unique volcanic formations, such as "farra" (pancake-shaped domes), and "arachnoids" (spider-web-like fractures). While Venus has fewer impact craters than Earth, their pristine state implies the surface is relatively young - around 300 to 600 million years old.
Recent studies propose that ancient Venus may have had plate tectonics and possibly even oceans, hinting that it could once have been habitable. However, without Earth-like plate tectonics today, Venus may release its internal heat through periodic, planet-wide resurfacing events.
We have limited direct information on Venus's internal structure because we lack certain seismic data. However, Venus and Earth are similar in size and density, so Venus likely has a core, mantle, and crust like Earth. Its core might be partially liquid due to similar cooling rates between the two planets, though it could also be solid.
Unlike Earth, Venus shows no evidence of plate tectonics. This may be because its crust is too rigid to shift without water, which on Earth helps make the crust more flexible. As a result, Venus retains more internal heat, which may explain why it lacks a magnetic field. Instead, it might release heat through occasional large resurfacing events.
In 1967, Venera 4 discovered that Venus has a very weak magnetic field, far less than Earth's. This field is not generated by an internal dynamo like Earth's, but rather by interactions between Venus's ionosphere and the solar wind. Because of this, Venus's atmosphere receives little protection from solar and cosmic radiation.
The lack of a magnetic field was unexpected. For a magnetic dynamo, a planet needs a rotating, connecting, and electrically conductive core. Venus's core likely meets these criteria, but convection might be lacking. Earth's core has convection due to temperature differences, but Venus's crust acts as an insulator, trapping heat in the mantle and limiting core convection.
Another theory is that Venus lacks a solid inner core or that its core is not cooling, possibly due to differences in sulfur levels. Alternatively, Venus may not have had a massive impact like Earth's Moon-forming event, which could have helped mix and activate its core.
The weak magnetic field allows the solar wind to strip away parts of Venus's atmosphere, particularly lighter elements like hydrogen and oxygen, which contribute to water loss. Over time, this stripping process has changed Venus's atmosphere, leaving a higher ratio of heavier deuterium to hydrogen, suggesting significant water loss over Venus's history.
Venus has a thick, hot, atmosphere made up mostly of carbon dioxide (96.5%) and nitrogen (3.5%) along with traces of other gases. The atmosphere is incredibly dense - 92 times the mass of Earth's and with surface pressures about 93 times higher than at sea level on Earth, similar to the pressure nearly a kilometer underwater on Earth. This thick carbon dioxide layer traps heat and creates an intense greenhouse effect, making Venus the hottest planet in our Solar System, with surface temperatures around 462 degrees Celsius, even hotter than Mercury.
Venus may once have had an atmosphere similar to early Earth's, with possible water on its surface billions of years ago. However, as the Sun brightened over time, any water likely evaporated, contributing to a runaway greenhouse effect. Today, Venus's surface is inhospitable to life, but some scientists speculate that life could exist in its upper cloud layers, where conditions are more Earth-like - temperatures range between 30 to 80 degrees Celsius with pressure similar to Earth's.
The atmosphere of Venus also has clouds of sulfuric acid and other chemicals, creating a reflective layer that blocks much of the sunlight. Only about 10% of sunlight reaches Venus's surface, so the light level is similar to an overcast day on Earth. Strong 300 km/hr winds at the cloud tops go around Venus about every four to five Earth days. Winds on Venus move up to 60 times the speed of its rotation, whereas Earth's fastest winds are only 10 to 20% of its rotation speed.
The surface of Venus is effectively isothermal; it retains a constant temperature not only between the two hemispheres but also between the equator and the poles. Venus's minute axial tilt - less than 3 degrees, compared to 23 degrees on Earth - also minimizes seasonal temperature variation. The highest point on Venus, Maxwell Montes, is therefore the coolest point on Venus, with a temperature of about 380 degrees Celsius and an atmospheric pressure of about 45 bar. In 1995, the Magellan spacecraft imaged a highly reflective substance at the tops of the highest mountain peaks, a "Venus snow" that bore a strong resemblance to terrestrial snow. This substance likely formed from a similar process to snow, albeit at a far higher temperature. Too volatile to condense on the surface, it rose in gaseous form to higher elevations, where it is cooler and could precipitate. The identity of this substance is not known with certainty, but speculation has ranged from elemental tellurium to lead sulfide (galena).
Although Venus has no seasons, in 2019 astronomers identified a cyclical variation in sunlight absorption by the atmosphere, possibly caused by opaque, absorbing particles suspended in the upper clouds. The variation causes observed changes in the speed of Venus's zonal winds and appears to rise and fall in time with the Sun's 11-year-old sunspot cycle.
The existence of lightening in the atmosphere of Venus has been controversial since the first suspected bursts were detected by the Soviet Venera probes. In 2006-2007, Venus Express detected whistler mode waves, the signatures of lightening. Their intermittent appearance indicates a pattern associated with weather activity. According to these measurements, the lightening rate is at least half that on Earth, however, other instruments have not detected lightening at all. The origin of any lightening remains unclear, but could originate from clouds or Venusian volcanoes.
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