Researchers from all over the world are still unable to tell whether our planet shrinks, expands or somehow pulses. What prevents them from making the final decision is the lack of objective data about Earth’s radius changes. However, Russian geologist from Russian Kant State University managed to use most recent data and concluded that Earth should be shrinking.

Science knows several hypotheses about the origin of our planet. According one of these hypotheses, the Earth appeared from a bunch of particles. Then, the planet rotated and got denser and denser. However, if the Earth was shrinking, then the area of the sphere with larger radius should have been somehow fitted on a lesser surface. Recent observations showed that Earth’s crust is shrinking – some parts of it settle down, and relief gets much more defined with higher mountains and deeper depressions. If we manage to measure the length of Earth’s “circle” according current and ancient relief patters, we can find out how the planet’s radius has changed since ancient times.

Taking crystalline basement of shields and platforms as a reference point will be very convenient. Russian scientists estimate the age of this relief to be about 4 billion years. Russian geologist, Vyacheslav Orlyonok, has measured amplitudes between ancient and current relief marks along the equator and following meridians – 30° E, 40° E, 60° W and 70° W – and calculated current and ancient radiuses of our planet. Well, it turned out that 4.5 billion years Earth’s average radius was 6956 kilometres and lost 585 kilometres since those times. Average compression speed of our planet was 1.46x10^-2 cm per year.

 

 

Since we know how Earth’s radius has changed, we can calculate our planet’s volume and surface area. The researcher showed that Earth’s surface lost 127 million square kilometres during 4.5 billion years – this figure can be compared with the area of existing continents (171 million square kilometres).

Radius and volume shrinking caused Earth’s crust to experience tensions and break to large elements, and this was how planetary system of troughs and earth crust faults formed. Dr. Orlyonok believes shrinking of Earth’s volume to be the defining mechanism for tectonic processes, which take place in Earth’s crust.

Among other things, our planet shrunk, because it kept losing heat and mass. Calculations show that hard solar radiation caused our planet to lose about 3.22×10²⁵ grams of hydrogen. Hydrogen atoms are known to have high thermal capacity, are highly volatile and penetrate even solid rocks – these molecules provided so-called “blowing-down” of Earth’s outer core, carrying out excessive heat, volatile chemical compounds and water.

Another reason for shrinking of our planet is called “gravitational contraction”. Particles of the rotating planet showed even tendency to centre of mass, and this process takes place with heat emission. Calculations show that energy of Earth’s gravitational contraction is about 4.7×10²⁰ Joules per year and causes radius shrinking of 1.3x10-3 cm per year. In other words, gravitational contraction provides only one tenth of total radius diminishing.

The knowledge of dependence between Earth’s radius decrease and heat flow value due to gravitational contraction allowed Dr. Orlyonok to estimate radius changes of other planets of the Solar system. During several billion years Venus’s radius lost 376 km, Mars’s – 204, Mercury’s – 104 kilometres and the Moon lost 10.4 km.

Source: Science News

Kizilova Anna