Earth as a Magnet

Earth and moon from spaceMagnets come in all shapes and sizes. There are horseshoe shaped magnets, natural rock magnets, small magnets, big magnets and… MASSIVE magnets.In fact you could call the Earth one GIANT spherical shaped magnet!

In this science blog we learn what the earth magnet ‘looks’ like and how our earth magnet protects us from dangerous sunlight and lethal solar winds.

  • Is sunlight really dangerous?

Everything in moderation! Too much sunlight of the wrong sort can be harmful.There are three different types of sunlight:

Visible light,which is the light we see with our eyes, is harmless.We see this light as colors of the rainbow.

woman standing under a rainbow with arms outstretched

Click on image for slide show

Infrared light,which is invisible to our eye, can sometimes be harmful. This is the light that makes us feel warmth from the sun. Look at these objects and animals to see what they look like under infrared light.

infrared cat showing heated eyes and ears

Ultraviolet light,which is also invisible to our eye, can be very damaging.Ultraviolet (UV) light is the type of light that gives us sunburn and is the main cause of skin cancer.

woman sunburnt on back from ultraviolet radiation

How fast does sunlight travel?

Sunlight travels amazingly fast at the incredible speed of 186,282 miles every second! The earth is ‘only’ 93 000 000 miles from the sun; in the picture below light from the sun has only taken 8 minutes and 19 seconds to reach us.

sun dipping below the horizon over sea on Earth

Mars, at a distance of 141,600,000 miles, is 48 600 000 miles further from the sun than earth is. The sunlight in the picture below has taken 12 minutes to reach Mars.

      • What differences do you notice between the two pictures?

sun dipping below horizon on planet Mars

What are solar winds?

The sun continuously ejects massive amounts of super heated particles from its outer atmosphere. These particles travel across our Solar System at more than one million miles an hour.

These particles form solar winds; solar winds travel far slower than the speed of sunlight and can take from 4 to 5 days to reach our planet.

the sun ejecting super heated particles from outer atmosphere

Why are solar winds dangerous?

Solar winds can strip away the atmosphere from a planet and send its atmosphere into deep space- unless that is, a planet receives some sort of protection.

Mars used to have a thick atmosphere much like earth’s but most of its atmosphere was ripped away billions of years ago as a result of the fact that the planet lost its protection against solar winds.

Image of the planet Mars

By contrast the Earth, although closer to the sun than Mars, is largely protected from lethal solar winds and has a dense atmosphere full of life supporting gases.

Close up of earth's atmosphere showing moon and curvature of the Earth

      • How is it that the earth has been protected from the damaging effects of solar winds but Mars has not?

Protection from solar winds- comparing the interiors of Mars and the Earth

To answer how and why the earth receives protection against solar winds we need to examine the interiors of both Mars and the Earth.

The inner core of Mars is composed of a ball of solid iron and nickel. As a result of having no liquid outer core, Mars has a very weak magnetic field.

Cross section of Mars showing solid core

Contrast this with the core of the earth; our planet has a solid iron/nickel inner core and a liquid metal outer core.

Diagram of Earth showing cross section with molten core

The outer liquid iron core of our planet creates the earth’s magnetic field. It is the earth’s magnetic field that protects us from the harmful effects of solar winds.

You can see the extent of the earth’s magnetic field in the diagram below. Were it not for this protection, the solar winds would blow away most of the gases in our atmosphere, sending them into deep space.

Diagram of Earth's magnetic field showing four poles and compass needle pointing north

The atmosphere protects us from harmful sunlight

Having an atmosphere protects us from harmful ultraviolet light. A gas in our upper atmosphere called ‘ozone’ absorbs ultraviolet light as it enters the atmosphere, reducing by 70% the amount of ultraviolet light that reaches the ground.

In contrast Mars has almost no ozone in its atmosphere, exposing the planet to very high doses of ultraviolet light.

diagram of Earth showing how ozone layer in upper atmosphere protects us from harmful ultraviolet light

How the earth’s magnetic field shelters us from solar winds

If it were not for our magnetic field, solar winds traveling  at speeds of up to one million miles an hour would rip the atmosphere away from our planet, sending ozone and other important gases off into deep space.

The earth’s magnetic field offers protection to our upper atmosphere by deflecting lethal solar winds around our planet, allowing important gases like ozone to remain in our atmosphere.

In withstanding constant battering by solar winds, the shape of the magnetic field, although distorted, remains intact.

diagram of earth's magnetic field protecting us from solar radiation

You can compare the distorting effects of solar winds on the earth’s magnetic field to the distorting effects of strong terrestrial winds on a tree on a windswept plain.

windswept tree used to illustrate how the solar winds distort the earth's magnetic field

If you watch this animation, you will see how our magnetic field deflects harmful solar winds away from the Earth.

      • As you watch, look at the solar winds which approach closest to Earth. Where does this happen?

When solar winds blow particularly hard you get some amazing light displays.These displays of light are caused when particles in the solar winds collide with gases in the earth’s upper atmosphere.

These magical light displays are called the ‘Aurora Borealis’ when seen near the North Pole and the Aurora Australis when seen near the South Pole.

You can watch what these light displays look like in the video below:

  • You can check the website of the Geophysical Institute of Alaska to see the likelihood of these light displays being seen day by day. You have to live quite far north or south to stand any chance of seeing them!

Science experiments

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