MOMENT OF INERTIA(TAMAS) & EFFECT ON PLANET OBLIQUITY

MOMENT OF INERTIA(TAMAS) & EFFECT ON PLANET

OBLIQUITY

The first and the basic fundamental is that, The axial tilt or obliquity of planet could not be primordial (Being or happening first in sequence of time). The most effective features which may be responsible for chaotic or even stable condition of axial tilt is moment of inertia, Spin rate, magnetosphere and it’s effects and solar tides etc. 

Yet, Now it is said as the axial tilt of outer planets are stable also the obliquity of planet like Mercury, Venus due to dissipative effects and earth due to capture of moon became stable. Where as the Mars is still chaotic vary from 0° to 60° (Ref J. lascar&P robutel Article name: Chaotic obliquity of the planets.)

Irrespective of several theories moment of inertia of  every individual planet may play an important role as far as axial tilt of planet is concern. Every planet of our solar system has an axial tilt even a mercury has small axial tilt (0.07°). Let us perform something, take a plastic ball and hang with a thread here your ball will not tilt. But hang a improper shape solid and hang it with a thread it will tilt from where the weight is more in a similar way the planets are bound with a thread of force of gravity from sun and a force which pulls the planet from opposite of force of gravity irrespective of their own rotating action in such case the matter (planet) try to attain a stable axial position around which it will revolve making axial tilt of planet. Where, As written above the respective celestial events are responsible for their respective stability of obliquity of the planet.

In practical way the "Great East Japan Earthquake" in 2011 may be the best example to say that the moment of inertia may play an important role as far as the obliquity of planet is concern. In 2011 as we know that, The quake moved portions of northeastern Japan by as much as 2.4 m (7.9 ft) closer to North America, making portions of Japan's landmass wider than before. Portions of Japan closest to the epicenter experienced the largest shifts. A 400 km (250 mi) stretch of coastline dropped vertically by 0.6 m (2.0 ft), allowing the tsunami to travel farther and faster onto land. One early estimate suggested that the Pacific plate may have moved westward by up to 20 m (66 ft), and another early estimate put the amount of slippage at as much as 40 m (130 ft).On 6 April the Japanese coast guard said that the quake shifted the seabed near the epicenter 24 meters (79 ft) and elevated the seabed off the coast of Miyagi prefecture by 3 meters. A report by the Japan Agency for Marine-Earth Science and Technology, published in Science on 2 December 2011, concluded that the seabed in the area between the epicenter and the Japan Trench moved 50 meters east-southeast and rose about 7 meters as a result of the quake. 

The earthquake shifted the Earth's axis by estimates of between 10 cm (4 in) and 25 cm (10 in). This deviation led to a number of small planetary changes, including the length of a day, the tilt of the Earth. The speed of the Earth's rotation increased, shortening the day by 1.8 microseconds due to the redistribution of Earth's mass. The axial shift was caused by the redistribution of mass on the Earth's surface, which changed the planet's moment of inertia. Because of conservation of angular momentum, such changes of "INERTIA" result in small changes to the Earth's rate of rotation.

NOTE: "TAMAS" IS A SANSKRIT WORD USED WHICH SCIENTIFICALLY MEANS INERTIA.