The sun affects everything from the weather we experience to the food we eat, and even our health. If the Earth did not rotate , one half of the Earth would always be hot and bright, and the other part would be frozen and dark. The Earth also moves around the sun. This movement is called a revolution, which is different from rotation. Objects rotate around an axis, but revolve around other objects. So the Earth rotates around its axis as it revolves around the sun.
It takes the Earth days, or one year, to complete a revolution. Leftover momentum from when planets were forming makes the Earth, and all planets in the solar system , rotate and revolve. As the solar system formed, many moving particle s clustered together. They formed a spinning mass. This mass eventually split into different bodies— planet s, moon s, asteroid s, and comet s. All these bodies revolve around the sun.
In addition, all planets kept their own rotating motion, including the Earth. The Earth rotates around its axis at a rate of about 1, kilometers 1, miles an hour. It revolves around the sun at a rate of , kilometers 67, miles an hour. Other Kinds of Rotation Planets are not the only round objects that rotate. Amusement park rides, such as Ferris wheel s or carousel s, also rotate. The Ferris wheel rotates around a horizontal axis, and the carousel rotates around a vertical one.
Wheels on a car rotate around a strong horizontal bar called an axle. The axle runs from one side of the vehicle to the other, connecting the front wheels to each other and the back wheels to each other. Many household items rotate, including sprinkler heads, beater s on a mixer, blades on a ceiling fan , and doorknobs. There are some things that rotate without a specific axis. Farmer s use crop rotation to help the soil stay healthy and plants receive the right nutrient s from season to season.
Crop rotation means growing things in a different spot each year. This helps prevent disease and encourage s the soil to be fertilize d by different crops.
For example, cabbage , broccoli , and sprouts are in the same plant family. If they were grown in the same place year after year, they could all develop clubroot disease , weakening or killing the crop and damaging the soil.
The field itself acts as an axis, with different crop s being rotated in at different times. The Tipped Earth Did you know that the Earth is tipped over? To get the best experience possible, please download a compatible browser. If you know your browser is up to date, you should check to ensure that javascript is enabled. A normal, hour, day is based on the mean speed of the rotation of the whole Earth, including its atmosphere and ocean. When the motions in these fluids move mass to different positions, the angular momentum changes in them and will affect the solid Earth rotation.
Given the rotation rate, fluid mass and distance from the Earth's radius, If one variable is changed, at least one other variable also must also change. For example, a spinning ice skater spins slower with extended arms and faster when his arms are pulled in.
Similarly, the spinning Earth is affected by many factors, including changes in the way the winds blow or currents in the ocean. Some of these factors can act to speed the planet up, while others literally drag it down.
Of course these effects are very small, but observable by advanced scientific techniques. The remarkable agreement demonstrates that a close coupling exists between motions of the atmosphere and the solid Earth.
Do these global processes affect deep geodynamics and tectonics? According to V. In the past few decades new concepts of global tectonics, such as plume tectonics, hot-spot tectonics and wrench tectonics, have been developed Dobretsov et al. Based on proved physical phenomena and palaeomagnetic data, in this chapter the author used M. The first model was discussed at the nd International Geological Congress Zemtsov, b. Modern Eurasia and the ancient lithospheric blocks it is made of were used subsequently as an example to analyze the continent rotation pattern which retards the mantle rotation Zemtsov, a.
The proper rotation of the Earth, like that of many other planets and stars, is one of the essential physical properties of this body. According to Robert Malcuit and co-workers, the main event in a series of events could have been related to the gravitational trapping of the Moon at ca.
If the Earth is understood as a homogeneous first-order body after M. Sadovsky, then its rotation could be described by a certain angular velocity. Cross-section through the Earth's shells and divisions A-O after V.
Zemtsov , based on geophysical data using the publications of Dobretsov et al. The vectors are shown arbitrarily as if they coincide with the linear velocity directions. These velocities are millions of times the velocities of tectonic movements. Considering these velocities as heat wind, S. The positive flow velocity in the liquid core relative to the lower mantle shows unambiguously that the flow velocity on the hard core surface is even higher and that the inner core has a higher ARV than the mantle ARV D.
It should be noted that as the Earth is not an absolutely solid body, its dimensionless inertia moment, estimated at 0. Conversely, the well-known compression of the Earth from the poles, slightly increases the estimated inertia moment. The greater the concentration of mass, the greater its moments of inertia, and the faster the body will spin.
We can borrow data from V. The rotation energy of the entire core or outer core is even harder to estimate, for its dimensionless inertia moment is also unknown, because the outer core is in semi-liquid state. For symbols, see Figure 2.
Annual fluctuations in mantle rotation energy are comparable in magnitude to oceanic circulation energy. Consequently, they can disturb this circulation, inevitably invoking global climatic changes. The assumed relationship between observed T fluctuations and climatic changes are discussed in the paper Sidorenkov, It appeared that the number of days in a year in the geological past can be estimated by calculating growth rings in fossil shells.
Such regularity has not been established unambiguously for Mesozoic time. Varga summed up all available data Lambeck, , ; Panella, ; Scrutton, ; Sonett et al. These combined and new data point to the steady and predictable LOD evolution and Earth—Moon distances over the last 1—2 Ga Kvale et al. With an age of about 2. In these works and below the author used a new Geologic Time Scale Gradstein et al. In this case, a geomagnetic field cannot be generated. Assuming the core radius to remain constant in time, average mantle retardation energy over the entire Phanerozoic E can be estimated using the equation Eq.
Part of this tremendous dissipation energy could have been a source of generation of the main geomagnetic field in Phanerozoic time. However, what part of mantle retardation energy could be absorbed by the core is unknown. Vertical segments are T estimation errors.
Red dotted line is present VDM value. Closer examination of the T-curve shows that it has a nonlinear quasi-periodical pattern. Consequently, a certain part of mantle retardation energy is absorbed by the core one way or another, although it cannot be great because, according to the Table 1 , core rotation energy is very small compared to mantle rotation energy.
Most of Palaeozoic mantle retardation energy was presumably used to restructure the geoid, oceanic circulations, anomalously high seismicity, tectonics, magmatism, etc. Palaeoseismicity over the interval Ma can be estimated indirectly.
Figure 4 shows that LOD had increased by about 1. Hence, LOD increased by approximately 5. This suggests that magnitude 10 earthquakes were not unusual in the Upper Palaeozoic.
In Phanerozoic time tidal energy dissipation values were shown by many authors to vary within 0. Zemtsov, A second similar see Fig.
Sparse known VDM-values at the end of this interval were probably also much smaller than at the present level and at the preceding time Fig.
This time is consistent with the disintegration of the assumed Rodinia supercontinent. However, Palaeozoic supercontinents are known to have existed up to the Jurassic period, when Phanerozoic T-anomaly was completed. The formation pattern and drifting of continents, as third-order structures, will be discussed below in more detail, but at the end of this interval 1. Horizontal dotted line is present VDM value approximately 8x10 22 Am 2.
It seems likely that no consensus will be obtained without further investigations to resolve these crucial issues. Strictly speaking, the mantle ARV is an unknown value. However, its viscosity is much greater than that of the liquid outer core see, layer E, on Fig. This qualitative estimate shows that the lithosphere could have slipped relative to the lower mantle if it had been integral instead of comprising an assemblage of plates. Thus, relative longitudinal eastward drift of the asthenosphere seems to occur, although it cannot have a strong influence on continental motions because continents as a rule move much faster, as will be shown below.
The curve for the migration of the terrestrial pole Fig. The pole position, the International Arbitrary Beginning IAB , is recognized as the mean value of instant poles in since at that time the Chandler oscillation had its smallest recorded amplitude.
Curves of variations in the North Pole of rotation of the Earth polhode relative to the International Arbitrary Beginning in N after Zemtsov, and the mean vectors of the secular migration of the pole in after Shcheglov, — solid line; in — after Tsuboi, — dotted line; in — after Wegener, , — dotted-point line.
A side of small squares is 3 m. The analysis of the polhodes clearly shows that in the "Earth's body" there are two more movements that differ in pattern and velocity and are related to the secular course of the pole.
The secular course is the slow and apparent movement of the pole along the meridian; it manifests itself in that as time goes by, the instant poles make Chandler oscillations and move further away from IAB. However, at first it was directed towards the 45 th meridian in the west system , in the s towards the 71 st meridian and in it moved towards the 78 th meridian, turning opposite to the real rotation of the Earth Zemtsov, a , Astronomers agree that this secular course cannot be explained by periodic changes in the axis of rotation of the Earth in space or by changes in the angle of its inclination to the ecliptic.
From the physical point of view, such a generalization is unreal. Firstly, the complex secular movement of NP in the 20th century to the west, from the 71 st - to the 78 th - meridian and along them, can be alternatively interpreted as the rotational-forward drift of both Eurasia and North America relative to IAB in the direction opposite to the secular course vector. All five observatories of the Latitude Service were located on continental lithosphere, and the results of their measurements pertain only to the continents of Eurasia and North America as third-order tectono-dynamic structures.
It is no accident that sections of the Earth at the 71 st th - meridians and in the opposite meridians extend across these continents. Secondly, the Earth is not a perfect sphere, and its lithosphere will tend to split up as it moves along a meridian.
In this case, the thin oceanic lithosphere would be expected to be the first to split up. Thirdly, common forward continental drift in the Northern Hemisphere can occur only when shear movements take place simultaneously along transform faults in the Arctic, Atlantic and Pacific Oceans Zemtsov, Finally, the North Pacific plate, as a fourth-order tectono-dynamic structure located between Eurasia and North America rotating clockwise, should rotate in the opposite direction, as was described in Vikulin, In this case, r can be calculated from coordinates of points with the Williams Aviation Formulary V1.
The error in r increases nonlinearly at great arc distances. We can apply a necessary correction using known mathematical tables specifying the segment elements of a circle Zemtsov, a. Such a method is used to estimate the degree of elasticity plasticity of the Eurasian plate at various points of its surface Zemtsov, , , a as it is now covered with a fairly dense permanent satellite geodetic network GPS monitoring.
The modern clockwise rotational drift of the Eurasian plate is clear Fig. Scheme showing bathymetric features in the Indian Ocean and the altitudes of surrounding land Naqvi, However, contrary to V. Utkin , the centre of rotation is not a point.
It manifests itself in the regional morphology Fig. The most important vectors of linear velocities obtained for Tibet and its surroundings are presented in Table 2. Although colleagues Zhiliang et al. They tentatively interpret these vortex motions and crustal deformations as a reflection of the lower crust rock rheology. According to Table 2, only the CSD point has very small horizontal displacement the reason for which is hard to find. It is located in close proximity to the source of the recent destructive earthquake that occurred in southwestern China Zemtsov, a.
The tectonics and seismicity of the Himalayas has been the subject of intense investigations by many geoscientists during the past few decades Kayal, ; Ramesh et al. Most of the earthquakes were assigned to a fixed depth 33 km as recorded in the catalog of the International Seismological Centre. It has not been possible to correlate the observed seismicity and tectonic features of the Himalayas with any realistic model, particularly the great earthquakes in this region are yet to be understood well.
Recent data shed some new light on tectonics of the Himalayas that differs from west to east Kayal, The Central Asian transition zone consists of numerous crust blocks of different sizes. The most active interblock zones limited the Pamirs, Tien Shan, Shan, and Bayanhar blocks as well as the north boundaries of the Indian Plate.
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