Space Planet Earth MODIS Map Showing Earth's Weather NASA

Published on February 16th, 2010 | by Yellow Magpie


Our Home Planet Earth: Third ‘Rock’ From The Sun

Planet Earth MODIS Map Showing Earth’s Weather NASA

Our home planet Earth is something that perhaps, at times, we take for granted. However, we owe our entire existence to this third ‘rock’ from the Sun.

Upon viewing pictures of the ‘Blue Planet’ one almost instantly realises what a misnomer the word ‘Earth’ truly is. It would be far more appropriate to call our home the ‘Ocean’. In fact, oceans covers more than two-thirds of the planet’s entire surface.

The Earth has a vast abundance of water. Because of the planet Earth’s distance from the Sun and its atmosphere, water exists in three states, liquid in the form of water, solid in the form of ice, and as a gas in the form of water vapour and steam.

The ice caps at the North and South poles are permanently covered in ice all-year round. The South Pole is built upon a continent while the Northern pole is just frozen water.
The Pale Blue Dot The Most Distant Image Of Planet Earth Six Billion Kilometres (3.7 billion miles) Away (Brown Layer Of Light On The Right Side Of The Picture)

Planet Earth: The Facts

The largest of the terrestrial planets, our planet Earth has a diameter of 12,756 kilometres ( 7,926 miles) and a mean surface temperature of 15 degrees Celsius. A day on our planet takes approximately 23 hours and 56 minutes while a year takes 365.25 days, the time it takes for our planet to orbit the Sun.

The planet’s landmasses are divided into continents which rise from the oceans and seas. Plate tectonics is the driving force behind the Earth’s ever-changing landscape.

The planet Earth is by far the most geologically active of all the other bodies in the Solar System. The Earth is divided into seven major plates and many, many smaller ones. These plates range in thickness from just a couple of kilometres thick to 110 kilometres (70 miles) at the ‘Cratons’ which are in the middle of the continents.

True Colour Picture Of Planet Earth NASA

True Colour Picture Of Planet Earth NASA

Below the Earth’s crust lies the mantle which is made up of partially molten rocks which continuously move causing currents. It is the mantle which carries heat from the inner core to the surface and sustains life.

An Active Geological System

Volcanoes and Earthquakes can arise due to faults in the Earth’s crust and the movement of the tectonic plates.

However, the Earth is the only planet in the Solar System that has tectonic movement. Water and size are thought to be the reasons for this being so.

As the largest terrestrial planet, the Earth also has the core with the highest temperature which helps to power tectonics. Water too, is thought to play a crucial role.

The asthenosphere is a thin fluid layer that resides between the crust and the mantle. Water is thought to lubricate the asthenosphere and allow for movement.

Internal Structure Of Planet Earth Picture By Surachit Creative Commons ShareAlike Licence

Internal Structure Of Planet Earth Picture By Surachit Creative Commons ShareAlike Licence

Water And Air: Our Lucky Circumstances

The planet Earth is surrounded by a thin layer of gas and water, the atmosphere and the hydrosphere. Both of these help to create the environment that we enjoy today and without which there would be no life on this planet.

Our distance from the Sun is incredibly fortuitous, as we are ideally located so that we neither freeze or roast. This is also coupled by the fact that our rotation is rather rapid which means that no side either freezes, from lack of exposure to the Sun, or wilts from too much solar exposure.

The tilt of the Earth also prevents our polar ice caps from extending too far and freezing other parts of the planet. The tilt also sustains seasons which in turn provide life.

Planet Earth's Changing Climate Photo By NASA

Planet Earth’s Changing Climate Photo By NASA

Water is continuously changing state. The water cycle from solid to liquid to gaseous states further fuel life on our planet. Water, or more precisely the water cycle, is responsible for absorbing carbon dioxide which plants in turn use as food from which oxygen is produced as a by-product. So we are blessed in many ways.

However, there is no really solid explanation as to where water came from in the first place. Because of the huge temperatures in the formation of the Earth, any water that was part of the planet would have been lost. Therefore, the water must have come from elsewhere.

The strongest theory suggests that comets laden with ice crashed into the Earth thus bringing the necessary precious water needed to sustain life.

Planet Earth And Life

Largely due to an extraordinary set of circumstances, life occurred on our planet Earth, the third ‘rock’ from the Sun. So strong is life’s foothold on Earth that nearly every part of the planet has a living organism in some shape or form. Water of course seems to be the main reason for the abundance of life on our planet. It was long thought that sunlight also plays a critical role in sustaining life.

Planet Earth Swiss National Park Photo By Hansueli Krapf Creative Commons ShareAlike Licence

Planet Earth Swiss National Park Photo By Hansueli Krapf Creative Commons ShareAlike Licence

This is largely true, however, maybe it is not always necessary. Scientists have discovered lifeforms feeding off the Earth’s own heat down at the bowels of the Ocean, a place where the Sun’s light does not penetrate. Geologists too, have found a bacteria, that they named ‘extremophile’, deep in the Earth’s crust.

Life on planet Earth could perhaps be as old as 4 billion years of age, much older than was previously thought. But it was only 600 million years ago that complex multi-celluar organisms developed. An event called the ‘Cambrian Explosion’ occurred approximately 550 million years ago. The was a highly fecund period which saw a massive growth in life.

All sorts of new species were born in this period and it remains one of the most fertile periods in the Earth’s history with a huge diversification of flora and fauna.

425 million years ago was the date that saw life take its first steps inland. The oxygen-rich environment saw invertebrates grow to enormous sizes, several feet long. Finally, the invertebrates followed paving the way for creatures such as Man to walk the planet.

Picture Of The Moon Viewed From A Space Shuttle Orbiting Planet Earth

Picture Of The Moon Viewed From A Space Shuttle Orbiting Planet Earth

Our Home

Our planet is completely unique. No matter what life exists in other worlds and remote galaxies, the Earth is special. No other planet in the Solar System is like our home. A fortuitous set of circumstances, thanks mainly to our Moon, may have caused life to take root on the Blue Planet. But life has grasped the opportunity and thrived in unimaginably harsh conditions.

We can thank our lucky stars for the planet Earth. Perhaps some day we will repay the favour.

Highly Recommended

You may like to check out The Solar System And Beyond: A Guide To The Cosmos

Cosmos by Giles Sparrow is highly recommended. Full of beautiful full page photographs and inspired explanations this large book is a most have for any home.
For people living in Ireland or the United Kingdom, you can access Cosmos here.
For those who live in Canada, you can obtain Cosmos from here.
For Germany: Cosmos.
For France: Cosmos.

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