The Earth’s magnetosphere was discovered in 1958 by Explorer 1. Prior to then, it was known that magnetic storms sometimes occurred because of solar eruptions and that electric currents did, in fact, exist in space. However, no one knew why or how they existed, and the presence of solar wind had not yet been discovered. Project Argus brought about that the discovery as it tested a theory regarding radiation belts and their formation.
The Size of the Magnetosphere
The magnetoshere is large and expansive. The sun-facing side, called the magnetopause, is about 70,000 kilometers, shrinking and growing depending on the power of the solar wind. This process determines the pressure on the magnetopause. The sides measure approximately one-quarter the distance to the moon, about 15 Earth radii in size. The tail on the right side stretches well beyond 200 Earth radii in size, and is the result of the stored energy being released from the magnetic field of the Earth. Unlike the Earth itself, the magnetosphere is not round in shape, but rather more of an oval. Solar winds, along with the internal magnetic field of the Earth are what give the magnetosphere its shape.
What Makes Up the Magnetosphere
Within the magnetosphere, there is a mixture of free electrons and ions from the solar winds and the Earth’s ionosphere. These are confined by the electromagnetic fields of the magnetosphere, which are stronger than the force of gravity. The environment within the magnetosphere is electronically neutral, requiring sensitive instrumentation, such as a compass needle, in order to detect the magnetic pull.
Outside of the magnetosphere, the sun dominates with a fast solar wind that is full of free electrons and ions it releases. The magnetosphere serves as a shield-like barrier, warding off those impressive solar winds that emanate from the sun. Without the protection of the magnetic field created by the Earth, the violent and deadly solar eruptions and winds would end all of the life that exists on Earth.
How the Magnetosphere Protects the Earth
The magnetosphere also helps protect life on Earth from the radiation emitted by gamma rays and cosmic rays. These highly energized rays beam from the sun at the speed of light toward the Earth. The gamma rays have the ability to travel through living tissue, adversely affecting DNA. Long-term effects include an increased risk of cancer. The magnetosphere also protects the Earth from supernovae and black holes.
The way that magnetosphere works is that charged gas particles, or plasma emitted by the sun, travel toward the Earth. When the plasma arrives, the magnetosphere interacts with the plasma and causes it to follow the magnetic lines toward the Earth’s poles, where the magnetic fields are the weakest. Here, the particles interact with a variety of gases, and become neutralized. This process creates a broad spectrum of colored lights in the sky, called the “northern lights,” or scientifically speaking, the “aurora borealis.” In the southern hemisphere, this would be called the “aurora australis.”
It is supposed that Mars, having a minimal, if any, magnetosphere, succumbed to the harsh solar emissions of the sun, and as a result, much of its atmosphere and oceanic properties were destroyed. Venus, too, is theorized to have lost its water sources to solar winds pushing through the thick atmosphere.
Consequently, without the magnetosphere, Earth’s atmosphere would crumble, and the planet would become as barren as Mars, Venus or any of the other dead planets. Working in conjunction with various other factors, the magnetosphere serves as one of the key elements that supports life on Earth.