Introduction
You may think that Earth seems dull in comparison with the remarkable and exciting collection of planets in our Solar System. There are no giant volcanoes like those on Mars, or 2,000 km/hr winds like those on Neptune. However, in many ways our world is is the most unusual of all. It is the only planet to have liquid water on its surface and a crust split into moving plates.
Changing Faces
Earth is the only planet in the Solar System that has a surface split into geological plates. These plates are constantly moving, and have been doing so for millions of years. About 250 millions years ago, all the continents were compressed together to form a single land mass, called Pangaea. This giant , moving land mass, formed of tectonic plates, crept slowly across the planet, carried on oceans of rocky mantle at a speed of about two centimeters each year. This eventually pulled the continents apart to the positions they hold now. The plates will continue to move well into the future. If we were able to see Earth in another 250 millions years, it would look completely different.
Earth's Birth
Earth formed from the same cloud of dust and debris as the sun. It started life as a glowing ball of molten rock, surrounded by a poisonous atmosphere of deadly gases. Over millions of years, it began to cool, and a solid crust formed. This crust was constantly torn and pulled by earthquakes and volcanoes, which spewed great amounts of steam into the atmosphere. Around 4 billion years ago, enough water had collected to form clouds.Violent storms created the first seas, and conditions became perfect for the development of life.
A living planet
Earth's chaotic surface patterns are formed by the movement of its plates. They do not move any faster than a human hair grows, but the incredible force behind them creates mountains, volcanoes and earthquakes. As the plates move, they often collide, or brush past one another. If two plates push against each other, they can crumple upwards to form enormous mountain ranges. Sometimes one plate is forced under another, melting in the hot Earth and erupting as a volcano. As plates brush past each other, snapping into new positions, they create shock waves that can destroy bridges and buildings.
Some important facts
1) Earth's atmosphere is divided into several layers, each containing different gases. it is held by Earth's gravitational pull, and stretches 640 km above the Earth's surface.
2) The mantle makes up most of the Earth, stretching for 2,900 km. It is made up of rock.
3) Pangaea, 250 millions years ago.
4) Pangaea breaks up. North America pulls away from Europe and Africa.
5) The continents as they are today.
6) Earth is the only planet to have liquid water on its surface. Water covers over 70% of the planet's surface area.
7) The outer core of the Earth's only liquid layer. It is made up of iron, nickel and sulphur and is 2.000 km deep. There is not enough pressure here to keep the iron solid.
8) Earth's core is made up mostly of iron and nickel. It is 1,370 km deep and is thought to have a temperature of 4,500oC. Pressure keeps the hot core solid.
9) The surface of Earth is called the crust. It is as deep as 70km under mountain ranges, but is as thin as 6km under the oceans. It is made up of rock.
Facts and Figures
Diameter: 12, 756km
Distance from sun: 150 million km
Average surface temperature: 15oC
Length of orbit: 365.25 Earth days
Length of day: 24 Earth hours
Density(water=1): 5.52
Number of moons: 1
Number of rings: 0
You may think that Earth seems dull in comparison with the remarkable and exciting collection of planets in our Solar System. There are no giant volcanoes like those on Mars, or 2,000 km/hr winds like those on Neptune. However, in many ways our world is is the most unusual of all. It is the only planet to have liquid water on its surface and a crust split into moving plates.
Changing Faces
Earth is the only planet in the Solar System that has a surface split into geological plates. These plates are constantly moving, and have been doing so for millions of years. About 250 millions years ago, all the continents were compressed together to form a single land mass, called Pangaea. This giant , moving land mass, formed of tectonic plates, crept slowly across the planet, carried on oceans of rocky mantle at a speed of about two centimeters each year. This eventually pulled the continents apart to the positions they hold now. The plates will continue to move well into the future. If we were able to see Earth in another 250 millions years, it would look completely different.
Earth's Birth
Earth formed from the same cloud of dust and debris as the sun. It started life as a glowing ball of molten rock, surrounded by a poisonous atmosphere of deadly gases. Over millions of years, it began to cool, and a solid crust formed. This crust was constantly torn and pulled by earthquakes and volcanoes, which spewed great amounts of steam into the atmosphere. Around 4 billion years ago, enough water had collected to form clouds.Violent storms created the first seas, and conditions became perfect for the development of life.
A living planet
Earth's chaotic surface patterns are formed by the movement of its plates. They do not move any faster than a human hair grows, but the incredible force behind them creates mountains, volcanoes and earthquakes. As the plates move, they often collide, or brush past one another. If two plates push against each other, they can crumple upwards to form enormous mountain ranges. Sometimes one plate is forced under another, melting in the hot Earth and erupting as a volcano. As plates brush past each other, snapping into new positions, they create shock waves that can destroy bridges and buildings.
Some important facts
1) Earth's atmosphere is divided into several layers, each containing different gases. it is held by Earth's gravitational pull, and stretches 640 km above the Earth's surface.
2) The mantle makes up most of the Earth, stretching for 2,900 km. It is made up of rock.
3) Pangaea, 250 millions years ago.
4) Pangaea breaks up. North America pulls away from Europe and Africa.
5) The continents as they are today.
6) Earth is the only planet to have liquid water on its surface. Water covers over 70% of the planet's surface area.
7) The outer core of the Earth's only liquid layer. It is made up of iron, nickel and sulphur and is 2.000 km deep. There is not enough pressure here to keep the iron solid.
8) Earth's core is made up mostly of iron and nickel. It is 1,370 km deep and is thought to have a temperature of 4,500oC. Pressure keeps the hot core solid.
9) The surface of Earth is called the crust. It is as deep as 70km under mountain ranges, but is as thin as 6km under the oceans. It is made up of rock.
Facts and Figures
Diameter: 12, 756km
Distance from sun: 150 million km
Average surface temperature: 15oC
Length of orbit: 365.25 Earth days
Length of day: 24 Earth hours
Density(water=1): 5.52
Number of moons: 1
Number of rings: 0
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