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Earth

Our Home

Our planet Earth was formed about 4.5 billion years ago. The Earth has a natural satellite called the Moon. Earth is the densest of all the rocky planets in our solar system and is made up of several layers. Below is a list of these layers and the depth of these layers in km:

  • Crust, 0 - 40

  • Upper Mantle, 40 - 400

  • Transition Region, 400 - 650

  • Lower Mantle, 650 - 2700

  • D'' Layer, 2700 - 2890

  • Outer Core, 2890 - 5150

  • Inner Core, 5150 - 6378





The outer layer of our planet is in constant motion due to a process called plate tectonics (continental shift). Continental plates float on the liquid magma and over a period of millions of years this movement has given us the shape of the continents. About 250 million years ago the Earth was made up of one large continent called Pangea.

The supercontinent of Pangea subsequently fragmented and the pieces now account for Earth's current continents which are still in motion today. Mountain ranges, which are found along the divisions between these continental plates, are the result of the plates colliding. Another disastrous consequence of these plate collisions are earthquakes. It took millions of years for the formation of the planets continents today and in millions of years time the earth might see another supercontinent as the plates are is constant motion. Click on the image below for a large view of the present day position of the plates.

 

 

 

 

 

Earth's Atmosphere

The atmosphere surrounds Earth and protects us by blocking out dangerous rays from the sun. The atmosphere is a mixture of gases that becomes thinner until it gradually reaches space. It is composed of Nitrogen (78%), Oxygen (21%), and other gases (1%). Oxygen is essential to life because it allows us to breathe. Some of the oxygen has changed over time to ozone. The the ozone layer filters out the sun's harmful rays. Recently, there have been many studies on how humans have caused a hole in the ozone layer. Humans are also affecting Earth's atmosphere through the greenhouse effect. Due to increases in gases, like carbon dioxide, that trap heat being radiated from the Earth, scientists believe that the atmosphere is having trouble staying in balance creating the greenhouse effect .

Magnetosphere

The Earth has a magnetic field which gives the planet its north and south poles. The Earth's magnetic field reaches 36,000 miles into space. The magnetic field of the Earth is surrounded in a region called the magnetosphere. The magnetosphere prevents most of the particles from the sun, carried in solar wind, from hitting the Earth. Some particles from the solar wind do make it through this protective barrier and the effects can be seen when observing the Aurora Borealis or the Northern Lights phenomena.

The Earth's Climate

The climate on Earth differs from region to region but the climate today is changing. Over 100 years ago, people worldwide began burning more coal and oil for homes, factories, and transportation. Burning these fossil fuels releases carbon dioxide and other greenhouse gases into the atmosphere. These added greenhouses gases have caused Earth to warm more quickly than it has in the past. Below is a list of some of the effects of climate change:

  • The rising of the sea level - During the 20th century, sea level rose about 15 cm (6 inches) due to melting glacier ice and expansion of warmer seawater.

  • The melting of arctic sea ice - The summer thickness of sea ice is about half of what it was in 1950. Melting ice may lead to changes in ocean circulation.

  • The warming of sea surface temperatures - Warmer waters in the shallow oceans have contributed to the death of about a quarter of the world's coral reefs in the last few decades.

  • Regional flooding - Warmer temperatures have led to more intense rainfall events in some areas. This can cause flooding.

  • Extreme drought - Higher temperatures cause a higher rate of evaporation and more drought in some areas of the world.

Facts about planet Earth

The Earth is almost a sphere as it bulges due to its rotation. The planet's shape resembles that of a football with someone sitting on it.What this means is that the measurement from pole to pole is about 43 km less than the diameter of Earth across the equator.

Earth is mostly iron, oxygen and silicon. If you could separate the Earth out into piles of material, you'd get 32.1 % iron, 30.1% oxygen, 15.1% silicon, and 13.9% magnesium. Of course, most of this iron is actually down at the core of the Earth. If you could actually get down and sample the core, it would be 88% iron. 47% of the Earth's crust consists of oxygen.

70% of the Earth's surface is covered by water.

Earth doesn't take 24 hours to rotate on its axis. It actually takes 23 hours, 56 minutes and 4 seconds.

A year on Earth isn't 365 days. It's actually 365.2564 days. It's this extra .2564 days that creates the need for leap years. That's why we add on an extra day in February every year divisible by 4 � 2004, 2008, etc � unless it's divisible by 100 (1900, 2100, etc)� unless it's divisible by 400 (1600, 2000, etc).

Earth is the only planet known to have life. We say this because Earth is the only planet where life has been discovered but when you take into consideration that our galaxy, The Milky Way, consists of approximately 400 billion stars with only a fraction of these that have been studied, one cannot ignore the fact that there is a possibility that one of these stars could provide the proper conditions to allow life to thrive on an orbiting planet.

Earth's gravity is not the same over the entire planet, you may actually feel heavier in some areas that you would in others.





 

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