Amanda is a retired educator with many years of experience teaching children of all ages and abilities in a wide range of contexts.
1. How Earth Was Formed
Earth is constantly changing and won't be the same planet one thousand years from now as we know today. But the formation of the earth started some 4.6 billion years ago. To answer the question of how the earth formed, we can break the process up into six stages.
- About 4.6 billion years ago, a dense cloud of gas and dust contracted to form the Sun. Other matter in the cloud formed solid clumps of ice and rock, and these joined together to form the planets.
- Radioactivity in the rocks caused the new-born Earth to melt. Iron and nickel sank into the center to form the earth's core, while oceans of molten rock floated to the surface.
- About 4 billion years ago, the earth's crust started to form. At first there were many small "plates" floating on the molten rock beneath.
- After millions of years, the crust thickened and volcanoes began to erupt. Gases poured out of the volcanoes to form the earth's atmosphere, and water vapor condensed to form the oceans.
- About 3.5 billion years ago most of the earth's crust had been formed, but the shapes of the continents looked very different from how they do today. The oldest rocks on earth date back to this very early period.
- Today, the earth continues to change. The earth's crust has broken up into huge slabs called "tectonic plates" that are constantly being destroyed and reformed at their edges. The continents we know today are still on the move, powered by churning forces of heat and molten rock and minerals deep beneath the surface.
2. The Anatomy of the Earth
The earth is made up of several layers of rock around a core of iron and nickel. The deeper the layer, the higher the temperature.
- The Inner Core
The earth's inner core has a diameter of approximately 1,700 miles (2,740 km). It's made up of solid iron and nickel. The temperature at the earth's core is thought to be about 8,100 degrees Fahrenheit (4,500 degrees Celsius).
- The Outer Core
The outer core of the earth is about 1,240 miles (2,000 km) deep. It's made up of liquid iron. nickel, and some oxygen.
- The Mantle
The layer called the "mantle" is a zone of mostly solid rock about 1,800 miles (2,900 km) deep. Just under 100 miles (160 km) down into the mantle, the rock is partially melted.
- The Crust
The earth's crust is the the relatively thin outer layer on which we live. It varies in depth from 4 to 43 miles (6 to 70 km) and is made up mostly of rocks similar to those we can see at the surface.
- The Atmosphere
The earth's atmosphere is a vital part of its composition as is protects the planet from harmful radiation from space. The atmosphere overall is about 400 miles (640 km) deep.
Diagram of the Earth's Layers
3. Drilling Deep into the Earth's Crust
The deepest mine in the world to date reaches 2.6 miles (4.2 km) into the earth's crust. Scientists undertaking a geological exploration, however, have drilled even deeper, taking samples from as a deep as 7.5 miles (12 km) below the surface. Even so, neither of these penetrations is anything like as deep as the bottom of the earth's crust at the point where it reaches the mantle.
4. Earth Science Data
4.6 billion years
5,854 billion billion tonnes
1,083,218,915,000cu km (259,877,796,843cu miles)
12, 756 km (7,962 miles)
12,713 km (7,899 miles)
40,075 km (24,901 miles)
39,942 km (24,819 miles)
Distance from the Sun
150 million km (93 million miles)
Time to Complete Axial Rotation
23 hours, 56 minutes, 4 seconds
Time to Orbit the Sun
365 days, 6 hours, 9 minutes, 9.5 seconds
5. Earth's Magnetic Field
Molten iron flowing in the earth's outer core generates electrical currents. These currents create the earth's magnetic field. This field, known as the "magnetosphere", stretches out beyond the earth to more than 60,000 km (37,000 miles) into space.
Sometimes, the earth's magnetic field "flips", meaning that north becomes south and south becomes north and vice versa. No-one yet understands why this phenomena happens. Scientists believe the last pole reversal took place about 30,000 years ago.
Did you know the earth has four poles? The geographical north and south poles lie on the earth's axis, an "imaginary line" around which the planet spins. The magnetic north and south poles lie just a short distance away from the geographical poles.
The pattern of the magnetic field spreads out in egg-shaped waves from the core. The field is strongest at the equator and the poles.
The Movement of the Earth's Magnetic Poles
6. Land and Sea
The earth's surface is divided into land and sea. But there's a lot more sea than land.
|Area of Land||Area of Sea|
7. The Non-Spherical Earth
Most people if asked to describe the shape of the earth will say that it's "round" or "spherical". But in fact, the earth isn't a perfect sphere. It's ever-so-slightly egg-shaped.
If a car could travel non-stop around the equator at say, 62 miles per hour, it would take about 16 days, 16 hours, and 45 minutes to complete the journey. But the same car driving around the earth from the north to the south pole and back would reach the finish line an hour and twenty minutes earlier!
8. Journey to the Center of the Earth
Unlike the events in popular science fantasy movies and books, it's impossible to journey to the center of the earth as it's made of solid iron and nickel and protected by a layer of molten metal and rock. But, if we imagine it was possible for an excavator to dig a hole at 1 m (39 inches) per minute right through the earth and out the other side, it would take 24 years!
9. Pricking the Earth with a Pin
If the earth were the size of an average chicken's egg, the deepest hole ever drilled by humankind (or anyone for that matter!) would not even manage to pierce its shell.
Composition of the Earth's Atmosphere
10. The Earth's Atmosphere
The earth's atmosphere is the film of gases that surrounds it in space. The atmosphere is divided into four main layers:
- the troposphere
- the stratosphere
- the mesosphere
- the thermosphere
The composition of the earth's atmosphere is 78% nitrogen, 21% oxygen, and the remaining 1% is made up of water and other gases.
Gravity holds the atmosphere in place. The atmosphere is vital for life on Earth as it stops the surface from becoming too cold or too hot and protects the land and sea from the sun's harmful ultraviolet rays.
Table of Facts About the Earth's Atmosphere
6 miles (10 km)
This is the layer which contains the clouds
31 miles (50 km)
Aircraft fly in this zone and it contains the ozone layer
50 miles (80 km)
"Meso" means "middle". So, this is the sphere in the middle between Earth and space
620 miles (1000 km)
Human-made satellites are launched into near space and orbit in this layer
Carl Sagan's Pale Blue Dot
A Last Word
That brings us to the end of our exploration of my top 10 interesting and fun facts about our home planet, the earth. I hope you've enjoyed reading about it. Of course, there're many hundreds, if not thousands, more facts to discover about the planet.
Scientists are constantly exploring and doing experiments to try and understand more about the only place in the known universe where it's possible for us to live. Much of that information is used to help protect the planet from harmful changes, many of them caused by human activity.
Perhaps one day, you'll be a scientist and help protect our beautiful planet for the future.
© 2019 Amanda Littlejohn
Amanda Littlejohn (author) on January 20, 2019:
Thanks for reading this article about Earth and sharing your experience watching the Discovery Channel show. That sounds very interesting!
Pamela Oglesby from Sunny Florida on January 20, 2019:
I think article is so interesting. I recently watched a TV show that I think was on the Dscovery channel that showe the areas where scientist were trying to dig the deepest holes. I think the deepest one was in Russia.
Regardless, I really enjoyed reading all the facts in your article, and it makes one wonder when some new change will happen again.