How it Works:
The Earth's magnetic field is created by currents in the core, and extends over one million kilometers into space. Inside this field, but outside Earth's atmosphere, there are particles trapped from the solar wind and from evaporation from the atmosphere. This collection of particles and fields is called the magnetosphere. Because charged particles and magnetic fields affect each other strongly, scientists studying the magnetospheric system have their hands full keeping track of all the things that can go on. It has taken nearly 100 years to understand what the basic components to this system are, and how they interact with each other.
The most important thing you need to understand as you read the material in this unit, is that currents of electrically-charged particles produce magnetic fields. To re-acquaint yourself with this very important idea, please conduct the following experiment:
Now let's look at the way this system works. Think of a system as a play that you may have read in English Class where there are several different actors, each with its own role to play.
The Main Characters (Basic Components):
Every system can be looked at in terms of the things that go into it and the things that come out. These are called 'inputs and outputs'. In nature it can be easy to identify what these are, but sometimes nature can be rather shy about letting you see them easily.
Remember, humans have senses that work well to detect some things in nature. These senses may not work well enough to see things that are very small (cells and atoms), things that are not present in large numbers (the sand grain in your shoe), or that do not easily absorb light (like the invisible air around you). Humans have created tools that extend our senses so that we can see atoms, magnetic fields and even the air we breath. These tools help us to see much more clearly the inputs and outputs to systems in nature.
What Goes in (Inputs):
Solar wind particles, electromagnetic radiation, and magnetic fields
Terrestrial atmospheric atoms (oxygen, hydrogen, helium)
What Comes Out (Outputs):
Electrical currents flowing into the atmosphere
Particles ejected into the solar wind
In order for a system to actually DO something, the parts of the system have to interact with each other. Sometimes we can see how these interactions take place, but other times they can be invisible. As these interactions take place, they actually cause the exchange of matter and energy within the system and change the inputs into outputs. When we start the engine of a car, we are not really aware of what it is that goes on within the engine to move the car forward. Somehow, the gasoline is chemically burned to release energy which then pushes on the pistons in the engine which then turn the crankshaft and the wheels. Scientists have only recently begun to understand what the processes are within the magnetosphere, and how they cause matter and energy to move about.
What Goes On Behind the Scenes (Processes in Action):
Currents of particles produce magnetic fields
Ring currents modify Earth's magnetic field
Particles are accelerated to higher energies
Solar storms cause magnetospheric storms
Aurora are produced during severe magnetospheric storms
Return to the Sun-Earth System