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Mapping Venus
New analysis supports theory that Venus' surface evolved through extreme makeover, not plate tectonics

Venus and Earth have long been thought of as sister planets. Given its similar size and proximity to Earth in the inner Solar System, Venus might seem like a promising candidate for having a surface that evolves through a tectonic process similar to what occurs on Earth, where rigid plates slowly shift across the underlying mantle.
But a recent analysis by Peter James, a graduate student in the Department of Earth, Atmospheric and Planetary Sciences, highlights the fact that Earth's plate tectonics seem to be the exception rather than the rule for rocky planets like Venus, Mars and Mercury.
James provides new evidence that the generation and recycling of the surface on Venus occurs through a process that is actually quite different from what happens on Earth. His finding supports a theory that first arose in the early 1990s, when NASA's Magellan spacecraft orbited Venus and took radar images of the planet's surface. Before Magellan, most scientists assumed that the surface of Venus was influenced by some form of plate tectonics or volcanism.

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Are Venus and Earth in a long-distance relationship?

The heart of Venus may belong to Earth. Our planet could be tugging on the core of Venus, exerting control over its spin.
Whenever Venus and Earth arrive at the closest point in their orbits, Venus always presents the same face to us. This could mean that Earth's gravity is tugging subtly on Venus, affecting its rotation rate. That idea, raised decades ago, was disregarded when it turned out that Venus is spinning too fast to be in such a gravitational "resonance".
But Earth could still be pulling on Venus by controlling its core, according to calculations by Gérard Caudal of the University of Versailles-Saint Quentin, France.

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Title: Rotation of rigid Venus: a complete precession-nutation model
Authors: L. Cottereau, J. Souchay

Context: With the increasing knowledge of the terrestrial planets due to recent space probes it is possible to model their rotation with increasing accuracy. Despite that fact, an accurate determination of Venus precession and nutation is lacking.
Aims : Although Venus rotation has been studied in several aspects, a full and precise analytical model of its precession-nutation motion remains to be constructed. We propose to determine this motion with up-to-date physical parameters of the planet
Methods: We adopt a theoretical framework already used for a precise precession-nutation model of the Earth, based on a Hamiltonian formulation, canonical equations and an accurate development of the perturbing function due to the Sun.
Results: After integrating the disturbing function and applying the canonical equations, we can evaluate the precession constant \dot{\Psi} and the coefficients of nutation, both in longitude and in obliquity. We get \dot{\Psi}=4474".35/Jcy ±66.5, corresponding to a precession period of 28965.10 ±437 years. This result, based on recent estimations of the Venus moment of inertia is significantly different from previous estimations. The largest nutation coefficient in longitude with an argument 2L_{S} (where L_{S} is the longitude of the Sun) has a 2"19 amplitude and a 112.35 d period. We show that the coefficients of nutation of Venus due to its triaxiality are of the same order of amplitude as these values due to its dynamical flattening, unlike of the Earth, for which they are negligible.

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VENUS130110B.jpg
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Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington


This image of Venus was captured on the 16th January, 2010, by the Wide Angle Camera (WAC) aboard the Messenger spaceprobe, when it was preforming a vulcanoid search.
Vulcanoids are small rocky bodies that have been postulated to exist in orbits between Mercury and the Sun, though no such object has yet been detected.  The best opportunities for the MESSENGER spaceprobe to search for vulcanoids are during perihelion passages, when the spacecraft's orbit brings it closest to the Sun. MESSENGER has searched for vulcanoids during three perihelion passages to date, in June 2008, in February 2009.
The Wide Angle Camera image has a 10.5° field of view.

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The International Astronomical Union (IAU)  has changed the name Metis Regio to Metis Mons for a 920-km wide Venusian feature located at 71.0N, 253.0E.
The feature is named after a Greek Titaness.

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The International Astronomical Union (IAU)  has removed the name Mnemosyne Regio for a Venusian feature that was located at 65.8N, 277.9E.
Newer mapping data showed that the term 'regio' is not appropriate for this region. The feature had been named after a Greek Titaness.

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The International Astronomical Union (IAU) has approved the name Azham Corona for the 380-km wide Venusian feature located at 66.4N, 252.7E.
The feature is named after a Northern Caucasus nature goddess.

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The International Astronomical Union (IAU) has approved new names for two small craters on Venus.
The 3.7 km wide crater Alina is located at Latitude 8.3, Longitude 267.78; and named after the shortened name Adeline (or Adelaide).
The 3.3 km wide crater Amelia is located at Latitude 8.57, Longitude 280.45; and named after the name Amelia.

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The International Astronomical Union (IAU) has approved  new names for Six Venus surface features:

Fulgora Dorsa, named after the Roman goddess of lightning, for a 463 km wide feature at Latitude: 78.5, Longitude: 342.0.
Heloha Fluctus, named after a Choktaw female thunderbird, for a 375 km wide feature at Latitude: 77.0, Longitude: 344.0.
Sarasvati Mons, named after a Hindu river goddess, for a 200 km wide feature at Latitude: 75.7, Longitude: 354.5.
Akka Tholus, named after a Finnish mother goddess, for a 19.4 km wide feature at Latitude: 75.1, Longitude: 233.0.
Eirene Tholus, named after a Greek goddess of peace, for a 58.0 km wide feature at Latitude: 75.5, Longitude: 230.0.
Yansa Tholus, named after a Brazilian goddess of wind and fire, for a 20.0 km wide feature at Latitude: 76.1, Longitude: 232.2.

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