Physicists have estimated the tidal heating of the Moon early Earth

Scientists theoretically analyzed tidal interaction between the earth and the Moon and found that on a scale of one hundred million years after the formation of the satellite they could significantly heating the planet by increasing its surface temperature a few degrees Celsius. This contribution is not enough to resolve the paradox of a weak young Sun, a conflict between reliable evidence of a warm climate on the early Earth and a relatively low heat flux from the stars, but in conjunction with other factors it will probably allow you to get closer to solving this problem. Preprint available at arXiv.org, published in peer-reviewed journal at the moment.

The paradox of a weak young Sun — the contradiction between paleoclimatic and astrophysical data, which to date has no satisfactory explanation. Research of geological (study of the forms of the rocks, isotopic analysis) suggests that on the early Earth (about four billion years ago) were warm and humid climate. However, according to modern ideas about the evolution of the Sun, the latter is radiated at the time, only 70 percent of current capacity — it could mean that the planet was much (tens of degrees Celsius) colder and the water it was freezing.

It is believed that the main role in maintaining the warm climate on the early Earth played the greenhouse effect: the composition of the gas shell of the planet enabled the sun effectively to be absorbed at the surface and in the lower atmosphere, but let the back radiation of energy. However, this factor alone does not provide a complete solution — in particular, does not explain the heating of the Earth in the first hundred million years of its existence, so scientists have to consider alternative scenarios of additional heat and the mechanisms of its preservation.

Physicists from Germany under the leadership of Rene Heller (rené Heller) from the max Planck Institute for Solar system research analyzed one of the possible mechanisms of occurrence of additional heat on the early Earth — tidal heating in the interaction of the planet with the Moon. The essence of this phenomenon is that the relative motion of the gravitational bodies bound may lead to variable deformations: the interior of the planet heats up from internal friction and transfer heat to the surface.

To estimate the amount of heat that was transferred Land, therefore, the authors have calculated the full energy of his own and the orbital rotation gravity couples directly after the formation of the moon and in our days. To do this, scientists have used the current observations of orbital periods and rotation of bodies and the estimates of the corresponding quantities in the past, suggesting both heavenly bodies, the solid balls of constant density. Then, the researchers suggested that the difference in energy (which made up about 99 percent of the original amount) by tidal interactions would be released in the form of heat according to the exponential law (that is, the rate of energy transfer was proportional to the remaining stock). After that, the researchers chose different typical duration for such a process, and calculated the increase in surface temperature of Land, which he could provide.

According to the results of calculations, with typical duration of one hundred million years (in the most favorable scenario) tidal heating could for over 150 million years to increase the surface temperature by 1-5 degrees Celsius. Such a result is not enough to fully compensate for the lack of warmth: for the existence of liquid water required heating of the surface by approximately five degrees Celsius, however, this value is much more significant than previously thought. The authors believe that further work this result in conjunction with other assessments will allow you to get closer to understanding the early history of our planet and, in particular, to resolve the paradox of a weak young Sun.

Earlier we talked about how the lack of heat on Earth tried to explain with the help of emission coronal mass ejection and fall to the planet’s surface by massive meteorites.

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