The internal structure of Venus and Earth evolved with a different pace, despite the fact that the planet likely formed under the same conditions, says us planetary scientist Joseph G. O’rourke (Joseph G. O’rourke). He proposed a model, according to which between the mantle and the core of Venus is still there may be oceans of magma. Article about it was published in Geophysical Research Letters.
Magma oceans of melted silicate rocks and metals were common on the terrestrial planets just after their formation. In the beginning, when large planetesimals formed the planets, the heat released by the gravitational coupling and the decay of radioactive elements, was enough to melt the substance from which these “building blocks” consisted of. Global magma ocean gradually hardened, forming the mantle and leaving the two liquid ocean — external and deep, basal.
Those oceans of magma, which was located on the surface hardened for the first 100 million years, however, the basal magma oceans that are between the solid mantle and the core, due to the slow sink could remain liquid for quite a long time.
Model of the formation of terrestrial planets from planetesimals and the evolution of magma oceans on the young planets widely developed, however, Joseph G. O’rourke (Joseph G. O’rourke) from the University of Arizona notes that Venus in this case is still given insufficient attention. So, the thematic review of the publisher Annual Reviews of Earth and Planetary Sciences on this planet is not a word, although very detailed, for example, magma oceans on the moon, which planet is not. American planetary scientist decided to fill this gap and, by adopting the combination of available observations and theoretical calculations, have developed a model in which the internal structure of Venus corresponds to the structure of the Earth two or three billion years ago.
It is assumed that, initially, both planets had the same structure, but this structure evolved with a different pace. The proximity of Venus to the Sun contributed to the fact that the magma ocean on the surface hardened it later, than on the Ground. Due to the high temperature of the Venusian surface and not-tectonic phenomena, the mantle of Venus is cooled down slower than the Land. Therefore, the layer of magma close to the top layer of the nucleus could remain molten on Venus is much longer than on our planet.
The simulation results showed that the Earth is 4.5 billion years igneous basal layer of the ocean to a depth of 750 kilometers was reduced to a thin layer — just one kilometer, and it is likely that dispersed in separate cavities. Venus during this same time the basal magma ocean “lost” only about 230 kilometers.
Now magnetic field on Venus’s very weak magnetosphere of the planet formed by ionized particles of the solar wind. However, the proposed O Rourke the model assumes that in the Venusian magma ocean could previously generated magnetic field according to different methods of calculation of this phenomenon could be terminated from 2.8 billion to 200 million years ago.
The deep magma ocean, if it still exists on Venus, could also affect how well the planet is deformed by tidal forces.
Finally, if, despite all these predictions, it appears that the basal magma ocean on the second planet from the Sun is actually there, it can be a indication that the initial conditions for the origin of the Earth and Venus were very different.
The author notes that he developed a hypothesis can confirm the exploration of Venus with spacecraft. Plans such interplanetary missions have NASA and Roscosmos — then scientists since 2005 to develop a draft apparatus “Venera-D”, and the American space Agency recently announced a competition for the development of the sensor for future Venusian Rover.