Topic-EarthTopic-Earth

Submitted by-AnamikaSubmitted by-Anamika

Submitted to- Gunjan MamSubmitted to- Gunjan Mam

EarthEarth Rom the perspective we get on Earth, our planet appears to be big and sturdy with Rom the perspective we get on Earth, our planet appears to be big and sturdy with

an endless ocean of air. From space, astronauts often get the impression that the an endless ocean of air. From space, astronauts often get the impression that the Earth is small with a thin, fragile layer of atmosphere. For a space traveler, the Earth is small with a thin, fragile layer of atmosphere. For a space traveler, the distinguishing Earth features are the blue waters, brown and green land masses and distinguishing Earth features are the blue waters, brown and green land masses and white clouds set against a black background. white clouds set against a black background.

Many dream of traveling in space and viewing the wonders of the universe. In Many dream of traveling in space and viewing the wonders of the universe. In reality all of us are space travelers. Our spaceship is the planet Earth, traveling at reality all of us are space travelers. Our spaceship is the planet Earth, traveling at the speed of 108,000 kilometers (67,000 miles) an hour. the speed of 108,000 kilometers (67,000 miles) an hour.

Earth is the 3rd planet from the Sun at a distance of about 150 million kilometers Earth is the 3rd planet from the Sun at a distance of about 150 million kilometers (93.2 million miles). It takes 365.256 days for the Earth to travel around the Sun (93.2 million miles). It takes 365.256 days for the Earth to travel around the Sun and 23.9345 hours for the Earth rotate a complete revolution. It has a diameter of and 23.9345 hours for the Earth rotate a complete revolution. It has a diameter of 12,756 kilometers (7,973 miles), only a few hundred kilometers larger than that of 12,756 kilometers (7,973 miles), only a few hundred kilometers larger than that of Venus. Our atmosphere is composed of 78 percent nitrogen, 21 percent oxygen and Venus. Our atmosphere is composed of 78 percent nitrogen, 21 percent oxygen and 1 percent other constituents. 1 percent other constituents.

Earth is the only planet in the solar system known to harbor life. Our planet's rapid Earth is the only planet in the solar system known to harbor life. Our planet's rapid spin and molten nickel-iron core give rise to an extensive magnetic field, which, spin and molten nickel-iron core give rise to an extensive magnetic field, which, along with the atmosphere, shields us from nearly all of the harmful radiation along with the atmosphere, shields us from nearly all of the harmful radiation coming from the Sun and other stars. Earth's atmosphere protects us from meteors, coming from the Sun and other stars. Earth's atmosphere protects us from meteors, most of which burn up before they can strike the surface. most of which burn up before they can strike the surface.

EarthEarth From our journeys into space, we have learned much about our home From our journeys into space, we have learned much about our home

planet. The first American satellite, Explorer 1, discovered an intense planet. The first American satellite, Explorer 1, discovered an intense radiation zone, now called the Van Allen radiation belts. This layer is radiation zone, now called the Van Allen radiation belts. This layer is formed from rapidly moving charged particles that are trapped by the formed from rapidly moving charged particles that are trapped by the Earth's magnetic field in a doughnut-shaped region surrounding the Earth's magnetic field in a doughnut-shaped region surrounding the equator. Other findings from satellites show that our planet's magnetic field equator. Other findings from satellites show that our planet's magnetic field is distorted into a tear-drop shape by the solar wind. We also now know is distorted into a tear-drop shape by the solar wind. We also now know that our wispy upper atmosphere, once believed calm and uneventful, that our wispy upper atmosphere, once believed calm and uneventful, seethes with activity -- swelling by day and contracting by night. Affected seethes with activity -- swelling by day and contracting by night. Affected by changes in solar activity, the upper atmosphere contributes to weather by changes in solar activity, the upper atmosphere contributes to weather and climate on Earth. and climate on Earth.

Besides affecting Earth's weather, solar activity gives rise to a dramatic Besides affecting Earth's weather, solar activity gives rise to a dramatic visual phenomenon in our atmosphere. When charged particles from the visual phenomenon in our atmosphere. When charged particles from the solar wind become trapped in Earth's magnetic field, they collide with air solar wind become trapped in Earth's magnetic field, they collide with air molecules above our planet's magnetic poles. These air molecules then molecules above our planet's magnetic poles. These air molecules then begin to glow and are known as the auroras or the northern and southern begin to glow and are known as the auroras or the northern and southern lights. lights.

EarthEarth The The inner core inner core is a solid section of the Earth and is unattached to the is a solid section of the Earth and is unattached to the

mantle, being suspended by the molten outer core. This solidified state is mantle, being suspended by the molten outer core. This solidified state is the result of a very intense pressure-freezing process that occurs in most the result of a very intense pressure-freezing process that occurs in most liquids when temperature decreases or pressure increases. The outer core liquids when temperature decreases or pressure increases. The outer core of Earth is a scorching hot, electrically conductive liquid in which of Earth is a scorching hot, electrically conductive liquid in which convection takes place. This inner layer in mutual combination with the convection takes place. This inner layer in mutual combination with the rotational motion of the Earth creates a dynamo effect where a force ield of rotational motion of the Earth creates a dynamo effect where a force ield of electrical currents is generated. This field is also known as Earth's electrical currents is generated. This field is also known as Earth's magnetic field, which is responsible for the functioning of mechanical and magnetic field, which is responsible for the functioning of mechanical and biological compasses. This field also causes a subtle jerking motion in the biological compasses. This field also causes a subtle jerking motion in the Earth's daily rotation. In terms of the physical aspects of the outer core, the Earth's daily rotation. In terms of the physical aspects of the outer core, the layer is dense, but not as dense as pure molten iron, evidencing the layer is dense, but not as dense as pure molten iron, evidencing the presence of multiple impurities having a lighter chemical makeup. presence of multiple impurities having a lighter chemical makeup. According to scientists, about 10% of this layer is composed of sulfur According to scientists, about 10% of this layer is composed of sulfur and/or oxygen due to the fact that these two elements are abundant in the and/or oxygen due to the fact that these two elements are abundant in the cosmos and dissolve readily in molten iron. cosmos and dissolve readily in molten iron.

EarthEarth D: The D" layer of Earth is about 3% of Earth's mass, is 125 to 188 miles D: The D" layer of Earth is about 3% of Earth's mass, is 125 to 188 miles

(200 to 300 kilometers) thick and covers about 4% of the mantle-crust (200 to 300 kilometers) thick and covers about 4% of the mantle-crust mass. This layer, in terms of whether it is part of the lower mantle or an mass. This layer, in terms of whether it is part of the lower mantle or an independent layer is still somewhat unclear. Based on evidence collected independent layer is still somewhat unclear. Based on evidence collected from seismic discontinuities, the D" layer might differ in chemical from seismic discontinuities, the D" layer might differ in chemical composition from the lower mantle above it.composition from the lower mantle above it.

The next layer, the Transition region comprises The next layer, the Transition region comprises 7.5% of Earth's mass 7.5% of Earth's mass with a depth of 250-406 miles (400-650 kilometers). This layer is also with a depth of 250-406 miles (400-650 kilometers). This layer is also known as the mesosphere and is 11.1% of the mantle-crust. It is made of known as the mesosphere and is 11.1% of the mantle-crust. It is made of mainly basaltic magmas with amounts of calcium, aluminum and garnet mainly basaltic magmas with amounts of calcium, aluminum and garnet (an aluminum-bearing silicate mineral). The layer becomes dense when the (an aluminum-bearing silicate mineral). The layer becomes dense when the garnet mineral cools but is buoyant and light when subject to heat due to garnet mineral cools but is buoyant and light when subject to heat due to the low melting points.the low melting points.

EarthEarth The outer core is in the range of 200 to 300 kilometers (125 to 188 miles) thick and represents The outer core is in the range of 200 to 300 kilometers (125 to 188 miles) thick and represents

about 4% of the mantle-crust mass. This layer is sometimes identified as part of the lower about 4% of the mantle-crust mass. This layer is sometimes identified as part of the lower mantle due to its geographical nature. However, studies on seismic discontinuities suggest that mantle due to its geographical nature. However, studies on seismic discontinuities suggest that this "D" layer might differ chemically rom the lower mantle lying above it. this "D" layer might differ chemically rom the lower mantle lying above it.

Looking at the Looking at the lower mantlelower mantle, its chemical omposition includes silicon, magnesium, and , its chemical omposition includes silicon, magnesium, and oxygen. Most likely, it probably also contains some iron, calcium, and aluminum. This layer is oxygen. Most likely, it probably also contains some iron, calcium, and aluminum. This layer is comprised of 72.9% of the antle-crust mass, making the Earth abundant in the chemical comprised of 72.9% of the antle-crust mass, making the Earth abundant in the chemical elements of silicon, magnesium and oxygen, the layer's primary components.elements of silicon, magnesium and oxygen, the layer's primary components.

3. Higher up, we encounter the 3. Higher up, we encounter the upper mantleupper mantle. Through excavations in volcanoes, scientists . Through excavations in volcanoes, scientists

have found that this part of the crust composes of 15.3% of the total mantle-crust mass and is have found that this part of the crust composes of 15.3% of the total mantle-crust mass and is made of crystalline forms of Olivine (Mg,Fe)2SiO4 and pyroxene (Mg,Fe)SiO3. The upper made of crystalline forms of Olivine (Mg,Fe)2SiO4 and pyroxene (Mg,Fe)SiO3. The upper mantle makes up 10.3% of the Earth's mass, extending a depth of 6-250 miles (10-400 mantle makes up 10.3% of the Earth's mass, extending a depth of 6-250 miles (10-400 kilometers). A relatively large portion when compared to the other interior layers. This layer is kilometers). A relatively large portion when compared to the other interior layers. This layer is not completely made of solid minerals for scientists speculate that the asthenosphere could be not completely made of solid minerals for scientists speculate that the asthenosphere could be partly liquid molten.partly liquid molten.

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