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Mercury's Atmosphere Has Been Updated Based on New Research

By: April Carson

The crust's high concentration of volatiles, such as sodium and sulfur, can't be accounted for by the hypothesis of enormous magma ocean evaporation on young Mercury. Rather, the planet's odd composition is more likely linked to the area where it was created in the protosolar nebula.

This is the conclusion drawn by planetary scientists, who have constructed the most complete theory of the magmatic ocean and primary atmosphere's joint development on young Mercury.

The Beginnings of Terrestrial Planets' Evolution

It is assumed that vast quantities of magma were involved in the initial formation and subsequent evolution and chemical differentiation of the terrestrial planets in the Solar System.

In approximately 20 million years, a rocky planet with a mass comparable to that of Mercury may finish the accretion process, build an iron core, and ensure the total solidification of its magma ocean.

The magma ocean hypothesis for the innermost planet Mercury is based on the fact that there is no water in the atmosphere, and it is difficult to explain without a magma ocean.

At the same time, as the planet's surface cools, chemicals are exchanged between the planet's interior layers and atmosphere and exosphere. This hypothesis has been verified by new research using computer models that improved the possible temperature conditions of the magma ocean, the temperature of convection in Mercury's mantle, and heating sources.

Model of extreme magma evaporation on young Mercury

At the end of the previous century, researchers proposed that the abnormally high bulk density of Mercury might be explained by the evaporation of components from the planet's surface early in its history, and that the planet's initial atmosphere should have evaporated slowly enough to stay in equilibrium with the magma ocean.

The presence of an ocean of magma on proto-Mercury is confirmed by the MESSENGER probe's findings that sodium and sulfur are abundant in the planet's surface layer.

Assuming the atmospheric composition of young Mercury

Noah Jäggi of the Physics Institute at the University of Bern has published the findings on young Mercury's joint evolution of the magma ocean and atmosphere, which was conducted by a team of planetary scientists.

The researchers employed five distinct coding systems that included the planet's composition, energy and mass transfers between the planet and the atmosphere, and exosphere matter loss due to plasma heating or photoionization.

For the initially big ocean of magma with a carbon and hydrogen content comparable to that of Earth, its existence might endure for almost tenths of thousands of years. This assured a slow loss of mass via the atmosphere (with an initial pressure of 5-12 bar) over a long time period.

A thin, short-lived atmosphere of metals and metal oxides would have existed if young Mercury did not have a great deal of carbon and hydrogen. In the upper levels of the atmosphere, which is rich in gases, H2 and CO predominated, while in the second situation – Na and SiO.

The process of degassing with the initial magma ocean was slower for Mercury than for other planets, which allowed early-formed mercury compounds to be preserved. The first effect on optical properties would have occurred at a height of less than 5 km above the surface.

Atoms excited by solar radiation or energetic particles (in particular, N) transform to a metastable state, which are unstable with respect to ground-state atoms. Depending on the atomic number of the atom, this condition is realized at different altitudes. This would have led to deep atmospheric layers becoming more transparent.

Conclusions and calculations

The amount of material lost from the young Mercury's exosphere by photoevaporation is calculated at 106.6 - 109.6 kilograms per second. The planet would have lost 0.3 percent or less than 0.02 percent of its water and sodium reserves during the magma ocean's existence.

Because of the comprehensive range of elements, even the most volatile ones such as Na and K are insignificant in comparison to the total amount present in young Mercury. This implies the sodium-rich crust of Mercury is unable to coexist with the theory of a huge loss of matter at the phase of the magma ocean, and its odd composition can be explained by the region from which it was formed.

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About the Blogger:

April Carson is the daughter of Billy Carson. She received her bachelor's degree in Social Sciences from Jacksonville University, where she was also on the Women's Basketball team. She now has a successful clothing company that specializes in organic baby clothes and other items. Take a look at their most popular fall fashions on

To read more of April's blogs, check out her website! She publishes new blogs on a daily basis, including the most helpful mommy advice and baby care tips! Follow on IG @bossbabymav







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