The Earth in space exists in a hostile environment and life on Earth should not be taken for granted, says David Marinelli

Earth’s geomagnetic field extends from the Earth’s centre to as much as 65,000km in space. The Earth self-generates the magnetic field in its core. Human understanding is that at the centre of the Earth there is an iron ball roughly the size of the moon that has solidified under pressure. This ball of iron floats in the middle of a sphere about the size of Mars, largely composed of molten iron and nickel. The temperature at the Earth’s core is 6,000 degrees Celsius. This core is surrounded by a solid mantel that is 2,900km deep made up of rock and various minerals with a crust at its surface. We walk on the crust of the Earth.

Simply put a magnetic field is the area around a magnet, in our case the Earth’s core, in which there is a magnetic force that moves electric charges. The molten iron and nickel core operates somewhat like an electricity generator, where the convective kinetic energy is converted to electrical and magnetic energy thus creating the electric currents creating the Earth’s magnetic field.

This is why on the surface of the planet a magnetic compass points north influenced by the electric magnetism in the magnetosphere. At Earth’s surface, this magnetic field is fairly weak, about 100 times weaker than that of a refrigerator magnet.

One of the reasons why the Earth is a habitable planet that is friendly to human life is because the Earth’s magnetic field shelters the planet from the harmful radiation coming from the sun, called the solar winds.

The solar wind is a stream of energised, electrically charged particles, primarily electrons and protons, flowing outward from the Sun, through the solar system at speeds of up to 800km per second and at a temperature of one million degrees Celsius, reaching the Earth in days.

In some animals, such as honey bees, the geomagnetic behavioural responses are as strong as the responses to light, smell or touch

The Earth’s magnetic field deflects most of the solar wind and the charged particles that would otherwise strip away the ozone layer that protects the Earth from harmful ultraviolet radiation.

If the material carried by the solar wind reached a planet’s surface, its radiation would exterminate any life that might otherwise exist. The Earth’s magnetic field serves as a shield, redirecting the material around the planet so that it streams beyond it. The force of the wind stretches out the magnetic field so that it is squashed inward on the sun-side and stretched out on the night side. This magnetic field is vital for keeping our atmosphere in place, thus protecting the biosphere that enables life on Earth to exist.

Over the past 50 years scientists have realised that hundreds of organisms such as bacteria, unicellular organisms and animals have the ability to detect and respond to this geomagnetic field. The discovery that living cells have the ability to build nanocrystals of the ferromagnetic mineral magnetite was key to this understanding.

In some animals, such as honey bees, the geomagnetic behavioural responses are as strong as the responses to light, smell or touch. Biologists have identified strong responses also in fish, amphibians, reptiles, numerous birds and a diverse variety of mammals including whales, rodents, bats, cows and dogs. In all of these cases, the animals are using the geomagnetic field as components of their homing and navigation abilities. It is in fact a sixth sense.

These magnetite crystals have now also been found within tissues of the human brain which means that we also may have a sub-conscious sense that allows our brain to detect the Earth’s magnetic field and to register magnetic shifts. The full extent of our magnetic sensibilities remains to be discovered.

The Earth in space exists in a hostile environment and life on Earth should not be taken for granted. The preconditions for life on Earth evolved over billions of years and continue to be kept in dynamic balance for us by nature. Nature, electricity, magnetic field, solar wind, magnetite, biosphere are names we have invented to talk about forces and processes that we do not really understand and that we exploit. It is not what they actually are. We should have the humility not to interfere with these processes and the wisdom to protect and restore them.

This article first appeared in the July edition of Senior Times. 

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