The Motion Of The Planet (Earth)

ABSTRACT

This study is on the motion of the planet. A planet is described as a celestial body that is in orbit around the Sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and has cleared the neighbourhood around its orbit. This study is aimed at the characteristics of the planet (earth) and its motion.

Table of contents

Cover page

Title page

Approval page

Dedication

Acknowledgement

Abstract

Chapter one

1.0      introduction

• Description of different types of planet
• Overview of planet earth
• Physical characteristics of the earth
• Orbit and rotation of the earth
• conclusion

References

CHAPETER ON

1.0                                                         INTRODUCTION

Planet broadly, is any relatively large natural body that revolves in an orbit around the Sun or around some other star and that is not radiating energy from internal nuclear fusion reactions. In addition to the above description, some scientists impose additional constraints regarding characteristics such as size, shape or mass. As the term is applied to bodies in Earth’s solar system, the International Astronomical Union (IAU), which is charged by the scientific community with classifying astronomical objects, lists eight planets orbiting the Sun; in order of increasing distance, they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto also was listed as a planet until 2006. Until the close of the 20th century, the only planets to be recognized were components of Earth’s solar system. At that time astronomers confirmed that other stars have objects that appear to be planets in orbit around them.

The main aim of this seminar is to discus planet in details. Specifically, the seminar was set to achieve the following purposes:

1. To study planet in details
2. To discuss different types of planet

• To study planet earth in full and its characteristic

1. To understand the Earth Orbit and rotation
   • DESCRIPTION OF DIFFERENT TYPES OF PLANET

The list of different types of planet is described as below:

Mercury 

It’s the nearest planet to the sun and is also the smallest planet in the solar system and takes around 88 days to complete one revolution (to be exact 88.97 days) which is the smallest time duration.

Its size is slightly larger than the size of the moon of earth. It does not have many moons and climatic conditions that are not favourable for any form of life as it is too near to the Sun. Its surface temperature ranges from 100 K at night to 700 K during the day (this high diurnal range of temperature is there because the planet has no atmosphere to retain and this is the highest among all planets).

It’s the second densest planet in our solar system with the smallest tilt in its axis among all the planets in the solar system. The picture of mercury is as shown fig.1 below:

Fig.1 picture of mercury

Venus

When observed from the Earth, it’s the second brightest (after the observed moon) and takes 224.7 Earth days to complete one revolution and 243 Earth days for rotation on its axis (it takes the maximum time period among all planets to complete one rotation). It rotates in the opposite direction to all planets except Uranus (from West to East).

It’s also observed that one day on Venus is equal to one year on Earth. It’s also called Earth’s twin sister because of its similar size, shape, mass, and proximity to the sun and of its bulky composition. It’s not suitable for human settlement because it contains 96% carbon in the atmosphere. The surface temperature is very high (a mean temperature of 735K), making it the warmest planet in our solar system. The picture of venus is as shown below:

Fig.2 picture of venus

Earth

It’s the third planet from the Sun and is the only known planet to arbour life.  The Earth age is around 4.5 billion years old. It takes 365.264 days to complete one revolution around the Sun and 24 hours to complete one rotation on its axis (and after every four complete revolutions 4years

it takes a day longer 366 days to complete a revolution). It is covered by 71% of water and its crust is divided into different tectonic plates (lithosphere). Earth’s innermost part remains active and its inner core is solid while the outer core is liquid which generates Earth’s magnetic field. The picture of earth is as shown below:

Fig.3 picture of earth

Mars

It’s the fourth planet from the sun and also the second-smallest in the solar system. Its red color also makes it known as the red planet (presence of iron oxide). It has two moons – Phobos and Deimos. Its gravity is 38% of the Earth’s gravity and takes 687 Earth’s day and one full Mars year (16,500 hours). The picture of Jupiter is as mars below:

Fig.4 picture of mars

Jupiter

It’s the fifth planet from the Sun and the largest planet among all. It’s also one of the brightest things that can be seen in the sky with the naked eye. Jupiter is a giant ball of gases with one-thousandth mass of the Sun and lacks a well-defined surface. The picture of Jupiter is as shown below:

Fig.5 picture of Jupiter

Saturn

It’s the sixth planet from the Sun and the second-largest planet among the solar system. It’s a giant gas planet with an average radius which is nine times the radius of the earth The inner core is made of iron and nickel. An electric current within the hydrogen layer gives rise to the magnetic field of the Saturn which is a little less than the earth’s magnetic field. The picture of saturn is as shown below:

Fig.6: picture of saturn

Uranus

It’s the seventh planet from the Sun and has the fourth-largest planet by mass and third-largest by radius. It’s also referred to as ice giants and its primary component is similar to Jupiter and Saturn but it also has more ices such as methane, water, and ammonia and also traces of hydrocarbons. It rotates in the opposite direction from all the planets except venus (it rotates from west to east). The picture of uranus is as shown below:

Fig.7. picture of uranus

Neptune

It’s the eighth planet from the Sun. It’s the fourth-largest planet by diameter. The third most massive planet and is the densest giant planet – it’s slightly larger than Uranus and Neptune. It orbits the Sun every 164.8 years and is denser than Uranus and physically smaller than Uranus. The picture of neptune is as shown below:

Fig.8 picture of neptune

1.2                                             OVERVIEW OF PLANET EARTH

Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth’s surface is land consisting of continents and islands. The remaining 70.8% is covered with water, mostly by oceans, seas, gulfs, and other salt-water bodies, but also by lakes, rivers, and other freshwater, which together constitute the hydrosphere. Much of Earth’s polar regions are covered in ice. Earth’s outer layer is divided into several rigid tectonic plates that migrate across the surface over many millions of years, while its interior remains active with a solid iron inner core, a liquid outer core that generates Earth’s magnetic field, and a convective mantle that drives plate tectonics.

Earth’s atmosphere consists mostly of nitrogen and oxygen. More solar energy is received by tropical regions than polar regions and is redistributed by atmospheric and ocean circulation. Greenhouse gases also play an important role in regulating the surface temperature. A region’s climate is not only determined by latitude, but also by elevation and proximity to moderating oceans, among other factors. Severe weather, such as tropical cyclones, thunderstorms, and heat waves, occurs in most areas and greatly impacts life.

Earth’s gravity interacts with other objects in space, especially the Moon, which is Earth’s only natural satellite. Earth orbits around the Sun in about 365.25 days. Earth’s axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth. The gravitational interaction between Earth and the Moon causes tides, stabilizes Earth’s orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest and most massive of the four rocky planets (WGS, 2020).

1.3                  PHYSICAL CHARACTERISTICS OF THE EARTH

Size and shape

The shape of Earth is nearly spherical. There is a small flattening at the poles and bulging around the equator due to Earth’s rotation. Therefore, a better approximation of Earth’s shape is an oblate spheroid, whose equatorial diameter is 43 kilometres (27 mi) larger than the pole-to-pole diameter.

The average diameter of the reference spheroid is 12,742 kilometres (7,918 mi). Local topography deviates from this idealized spheroid, although on a global scale these deviations are small compared to Earth’s radius: the maximum deviation of only 0.17% is at the Mariana Trench (10,925 metres or 35,843 feet below local sea level), (Stewart, et al, 2019) whereas Mount Everest (8,848 metres or 29,029 feet above local sea level) represents a deviation of 0.14%.The point on the surface farthest from Earth’s center of mass is the summit of the equatorial Chimborazo volcano in Ecuador (6,384.4 km or 3,967.1 mi) (Stewart, et al, 2019).

In geodesy, the exact shape that Earth’s oceans would adopt in the absence of land and perturbations such as tides and winds is called the geoid. More precisely, the geoid is the surface of gravitational equipotential at mean sea level (MSL). Sea surface topography are water deviations from MSL, analogous to land topography (Morgan et al, 2010).

Chemical composition

Earth’s mass is approximately 5.97×10²⁴ kg (5,970 Yg). It is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminum (1.4%), with the remaining 1.2% consisting of trace amounts of other elements. Due to mass segregation, the core region is estimated to be primarily composed of iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements (Morgan et al, 2010).

The most common rock constituents of the crust are nearly all oxides: chlorine, sulfur, and fluorine are the important exceptions to this and their total amount in any rock is usually much less than 1%. Over 99% of the crust is composed of 11 oxides, principally silica, alumina, iron oxides, lime, magnesia, potash, and soda (Morgan et al, 2010)..

Internal structure

Earth’s interior, like that of the other terrestrial planets, is divided into layers by their chemical or physical (rheological) properties. The outer layer is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle. The crust is separated from the mantle by the Mohorovičić discontinuity. The thickness of the crust varies from about 6 kilometres (3.7 mi) under the oceans to 30–50 km (19–31 mi) for the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as the lithosphere, which is divided into independently moving tectonic plates (Deuss et al, 2014).

Heat

The major heat-producing isotopes within Earth are potassium-40, uranium-238, and thorium-232. At the center, the temperature may be up to 6,000 °C (10,830 °F), and the pressure could reach 360 GPa (52 million psi). Because much of the heat is provided by radioactive decay, scientists postulate that early in Earth’s history, before isotopes with short half-lives were depleted, Earth’s heat production was much higher (Deuss et al, 2014).

Surface

The total surface area of Earth is about 510 million km² (197 million sq mi). Of this, 70.8%,or 361.13 million km² (139.43 million sq mi), is below sea level and covered by ocean water. Below the ocean’s surface are much of the continental shelf, mountains, volcanoes, oceanic trenches, submarine canyons, oceanic plateaus, abyssal plains, and a globe-spanning mid-ocean ridge system. The remaining 29.2%, or 148.94 million km² (57.51 million sq mi), not covered by water has terrain that varies greatly from place to place and consists of mountains, deserts, plains, plateaus, and other landforms. The elevation of the land surface varies from the low point of −418 m (−1,371 ft) at the Dead Sea, to a maximum altitude of 8,848 m (29,029 ft) at the top of Mount Everest. The mean height of land above sea level is about 797 m (2,615 ft) (Staff, 2007).

Gravitational field

The gravity of Earth is the acceleration that is imparted to objects due to the distribution of mass within Earth. Near Earth’s surface, gravitational acceleration is approximately 9.8 m/s² (32 ft/s²). Local differences in topography, geology, and deeper tectonic structure cause local and broad, regional differences in Earth’s gravitational field, known as gravity anomalies (Gomez, 2011)

Magnetic field

The main part of Earth’s magnetic field is generated in the core, the site of a dynamo process that converts the kinetic energy of thermally and compositionally driven convection into electrical and magnetic field energy. The field extends outwards from the core, through the mantle, and up to Earth’s surface, where it is, approximately, a dipole. The poles of the dipole are located close to Earth’s geographic poles. At the equator of the magnetic field, the magnetic-field strength at the surface is 3.05×10⁻⁵ T, with a magnetic dipole moment of 7.79×10²² Am² at epoch 2000, decreasing nearly 6% per century (Harvey et al, 2020).

Magnetosphere

The extent of Earth’s magnetic field in space defines the magnetosphere. Ions and electrons of the solar wind are deflected by the magnetosphere; solar wind pressure compresses the dayside of the magnetosphere, to about 10 Earth radii, and extends the nightside magnetosphere into a long tail. Because the velocity of the solar wind is greater than the speed at which waves propagate through the solar wind, a supersonic bow shock precedes the dayside magnetosphere within the solar wind. Charged particles are contained within the magnetosphere; the plasmasphere is defined by low-energy particles that essentially follow magnetic field lines as Earth rotates (Harvey et al, 2020).

1.4                                  ORBIT AND ROTATION OF THE EARTH

Rotation

Earth’s rotation period relative to the Sun—its mean solar day—is 86,400 seconds of mean solar time (86,400.0025 SI seconds). Because Earth’s solar day is now slightly longer than it was during the 19th century due to tidal deceleration, each day varies between 0 and 2 ms longer than the mean solar day.

Earth’s rotation period relative to the fixed stars, called its stellar day by the International Earth Rotation and Reference Systems Service (IERS), is 86,164.0989 seconds of mean solar time (UT1), or 23^h 56^m 4.0989^s. Earth’s rotation period relative to the precessing or moving mean March equinox (when the Sun is at 90° on the equator), is 86,164.0905 seconds of mean solar time (UT1) (23^h 56^m 4.0905^s). Thus the sidereal day is shorter than the stellar day by about 8.4 ms (Huebsch et al, 2017).

Apart from meteors within the atmosphere and low-orbiting satellites, the main apparent motion of celestial bodies in Earth’s sky is to the west at a rate of 15°/h = 15’/min. For bodies near the celestial equator, this is equivalent to an apparent diameter of the Sun or the Moon every two minutes; from Earth’s surface, the apparent sizes of the Sun and the Moon are approximately the same (Huebsch et al, 2017).

Orbit

Earth orbits the Sun at an average distance of about 150 million km (93 million mi) every 365.2564 mean solar days, or one sidereal year. This gives an apparent movement of the Sun eastward with respect to the stars at a rate of about 1°/day, which is one apparent Sun or Moon diameter every 12 hours. Due to this motion, on average it takes 24 hours—a solar day—for Earth to complete a full rotation about its axis so that the Sun returns to the meridian. The orbital speed of Earth averages about 29.78 km/s (107,200 km/h; 66,600 mph), which is fast enough to travel a distance equal to Earth’s diameter, about 12,742 km (7,918 mi), in seven minutes, and the distance to the Moon, 384,000 km (239,000 mi), in about 3.5 hours (Williams et al, 2017)

The Moon and Earth orbit a common barycenter every 27.32 days relative to the background stars. When combined with the Earth-Moon system’s common orbit around the Sun, the period of the synodic month, from new moon to new moon, is 29.53 days. Viewed from the celestial north pole, the motion of Earth, the Moon, and their axial rotations are all counterclockwise. Viewed from a vantage point above the Sun and Earth’s north poles, Earth orbits in a counterclockwise direction about the Sun. The orbital and axial planes are not precisely aligned: Earth’s axis is tilted some 23.44 degrees from the perpendicular to the Earth-Sun plane (the ecliptic), and the Earth-Moon plane is tilted up to ±5.1 degrees against the Earth-Sun plane. Without this tilt, there would be an eclipse every two weeks, alternating between lunar eclipses and solar eclipses (Williams, 2004)

Conclusion

At end of this study we were able to study how the planet move focusing on the earth  Earth spins around its axis, just as a top spins around its spindle. This spinning movement is called Earth’s rotation. At the same time that the Earth spins on its axis, it also orbits, or revolves around the Sun. This movement is called revolution. A pendulum set in motion will not change its motion, and so the direction of its swinging should not change. However, Foucault observed that his pendulum did seem to change direction. Since he knew that the pendulum could not change its motion, he concluded that the Earth, underneath the pendulum was moving

References

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