Why is Earth a Magnet? (Part One)

Earth’s Inconstant Magnetic Field.

Our planet’s magnetic field is in a constant state of change, say researchers who are beginning to understand how it behaves and why.

Earth has a large-scale magnetic field. Solar wind is deflected away from Earth, protecting the atmosphere. Earth has a magnetic field, but obviously that is not what is really happening. So what is really happening?

No one knows for sure, but there is a working theory currently making the rounds. As seen on the left, the Earth’s core is thought to consist largely of molten iron (red). But at the very core, the pressure is so great that this superhot iron crystallizes into a solid. Convection caused by heat radiating from the core, along with the rotation of the Earth, causes the liquid iron to move in a rotational pattern. It is believed that these rotational forces in the liquid iron layer lead to weak magnetic forces around the axis of spin.

The Earth has a substantial magnetic field, a fact of some historical importance because of the role of the magnetic compass in exploration of the planet.

A magnetic field is the area of influence exerted by a magnetic force. This field is normally focused along two poles. These poles are usually designated as north and south. However these directions are not the only two that a magnetic field can have. Most magnetic objects are composed of many small fields called domains. Here are some basic concepts of a magnetic field. The first real study of magnetism started during the 1600s and we are still trying to understand how the magnetic field works.

Second a magnetic field is the result of electric currents. An electric current is an electric charge moving in a defined path. This movement is what creates magnetic fields. The current can create a magnetic field as large as the Sun’s magnetosphere and as small as the domain of an atom. The important thing to know is that one is the companion of the other. Without an electric field you can’t have a magnetic field.

The next thing to be aware with a magnetic file is that opposites attract. Like poles in magnets will always repel each other while poles that are opposite in nature will attract each other. It is thanks to this phenomenon that scientist were actually able to diagram the lines of force.

So what is the importance of the magnetic field? The answer is that it is very vital to many aspects of life on earth. Because of its relationship with electricity we use it to produce and harness electrical currents in modern devices from blenders to power turbines. On the larger scale the Earth’s magnetic field called the magnetosphere helps to screen out the most harmful types of cosmic radiation. It also plays an important role in physics as the electromagnetic force is considered as one of the four fundamental forces in the known universe. Scientists are now looking to find a unified field theory that will properly explain the interaction between these forces.

You can’t see it, but there’s an invisible force field around the Earth. Not a force field, exactly, but a gigantic magnetic field surrounding the Earth, and it acts like a force field, protecting the planet – and all the life – from space radiation. Let’s take a look at the Earth’s magnetic field.

The Earth is like a great big magnet. The north pole of the magnet is near the top of the planet, near the geographic North Pole, and the South Pole is near the geographic South Pole. Magnetic field lines extend from these poles for tens of thousands of kilometers into space; this is the Earth’s magnetosphere.

Scientists think that electrical currents flowing in the liquid outer core deep inside the Earth generate the Earth’s magnetic field. Although it’s liquid metal, it moves around through a process called convection. And the movements of metal in the core set up the currents and magnetic field.

As we mentioned at the top of this article, the magnetic field of the Earth protects the planet from space radiation. The biggest culprit is the Sun’s solar wind. The Earth’s magnetosphere channels the solar wind around the planet, so that it

doesn’t impact us. Without the magnetic field, the solar wind would strip away our atmosphere – this is what probably happened to Mars. The Sun also releases enormous amounts of energy and material in coronal mass ejections. These CMEs send a hail of radioactive particles into space. Once again,

the Earth’s magnetic field protects us, channeling the particles away from the planet, and sparing us from getting irradiated.

  • Why is Earth geologically active?
 Internal heat drives geological activity, and Earth retains plenty of internal heat because of its relatively large size for a terrestrial world. This heat causes mantle convection and keeps Earth’s lithosphere thin, ensuring active surface geology. It also keeps part of Earth’s core melted, and the circulation of this molten metal creates Earth’s magnetic field.
  • What processes shape Earth’s surface? 
The four major geological processes are impact cratering, volcanism, tectonics, and erosion. Earth has experienced many impacts, but most craters have been erased by other processes. We owe the existence of our atmosphere and oceans to volcanic outgassing. A special brand of tectonics—plate tectonics—shapes much of Earth’s surface. Ice, water, and wind drive rampant erosion on our planet.
  •  What unique features of Earth are important for life?
  •  
Unique features of Earth on which we depend for survival are surface liquid water, made possible by Earth’s moderate temperature; atmospheric oxygen, a product of photosynthetic life; plate tectonics, driven by internal heat; and climate stability, a result of the carbon dioxide cycle, which in turn requires plate tectonics.

Earth’s magnetic field (also known as the geomagnetic field) is the magnetic field that extends from the Earth’s inner core to where it meets the solar wind, a stream of energetic particles emanating from the Sun.

The earth’s molten core causes the magnetic field, which is what makes life on earth possible.

The magnetic field acts as a shield to cosmic and solar rays that are constantly bombarding our planet.

Without a magnetic field, these rays would eventually destroy our atmosphere and make the planet inhabitable like Mars.

Relationship between Earth’s Magnetic Field and Ocean Currents?

In lava flows, the direction of the field is “frozen” in small magnetic particles as they cool, giving rise to a thermoremanent magnetization. In sediments, the orientation of magnetic particles acquires a slight bias towards the magnetic field as they are deposited on an ocean floor or lake bottom. This is called detrital remanent magnetization.

Thermoremanent magnetization is the form of remanence that gives rise to the magnetic anomalies around ocean ridges. As the seafloor spreads, magma wells up from the mantle and cools to form new basaltic crust. During the cooling, the basalt records the direction of the Earth’s field. This new basalt forms on both sides of the ridge and moves away from it. When the Earth’s field reverses, new basalt records the reversed direction. The result is a series of stripes that are symmetric about the ridge. A ship towing a magnetometer on the surface of the ocean can detect these stripes and infer the age of the ocean floor below. This provides information on the rate at which seafloor has spread in the past.

This forms the basis of magnetostratigraphy, a geophysical correlation technique that can be used to date both sedimentary and volcanic sequences as well as the seafloor magnetic anomalies.

Temporary dipole tilt variations that take the dipole axis across the equator and then back to the original polarity are known as excursions.

Due to the partial covalency of water’s hydrogen bonding, electrons are not held by individual molecules but are easily distributed amongst water clusters giving rise to coherent regions capable of interacting with local electric and magnetic fields and electromagnetic radiation.

Electric effects on water.

  • Ocean water being a conductor of electricity, 
the magnetic field induced by the ocean as it flows through the Earth’s main
field may depend on time and manifest itself globally as secular variation. This explains, in particular, the geomagnetic jerks, and the recently discovered correlation between secular variation and climate. Spatial correlation between ocean currents and secular variation is also strong.

The earth’s molten core causes the magnetic field, which is what makes life on earth possible. The magnetic field acts as a shield to cosmic and solar rays that are constantly bombarding our planet. Without a magnetic field, these rays would eventually destroy our atmosphere and make the planet inhabitable like Mars.

When solar wind particles run into a magnetic field, they are deflected and spiral around the magnetic field lines. One glorious effect seen when the solar wind interacts with a planet’s magnetic field is aurorae. Aurorae are shimmering light displays produced by molecules in the upper atmosphere. Particles with enough energy can leave the belts and spiral down to the atmosphere to collide with molecules and atoms in the thermosphere of a planet. The glow of the aurorae is the emission line spectra produced by the electrons in the rarefied gas dropping back down to lower atomic energy levels.

Aurorae in the Earth’s atmosphere occur many tens of kilometers above the surface and pose no threat to life on the surface below. They make some spectacular displays that look like shimmering curtains or spikes of different colors of light. In the northern hemisphere, the aurorae are called aurora borealis or “the northern lights” and in the southern hemisphere, they are called aurora australis or “the southern lights.” Occasionally the aurorae seem to erupt with a burst of activity of multi-color shimmering of reds, whites, and purples. This happens when stressed or flexing magnetic field lines about a third of the way to the Moon squeeze together and reconnect. That sends a massive burst toward the Earth that hits the upper atmosphere to make the aurora eruption.

The Earth’s magnetic field is attributed to a dynamo effect of circulating electric current, but it is not constant in direction. Rock specimens of different age in similar locations have different directions of permanent magnetization. Evidence for 171 magnetic field reversals during the past 71 million years has been reported.

Although the details of the dynamo effect are not known in detail, the rotation of the Earth plays a part in generating the currents which are presumed to be the source of the magnetic field.

Interaction of the terrestrial magnetic field with particles from the solar wind sets up the conditions for the aurora phenomena near the poles.

Animal magnetism: how wave, tidal energy affect sea life.

What is wave power?

Wave power is renewable energy derived from ocean waves. It is the kinetic energy of wind interacting with water and creating waves, said Peter Asmus.

Previous research has indicated that lake-migrating sockeye salmon fry have compass directional preferences, cued in part by magnetic fields. This paper reports the results of experiments designed to compare the magnetosensory system of salmon with those of other organisms. Unlike birds, the fry did not reverse their compass orientation 180° when the magnetic field’s vertical component was inverted, but rather displayed northerly (31°) orientation similar to that of fry in two different control conditions (325° and 22°). These results agreed with the 349° bearing displayed in 1979.

The mechanism of magnetic detection in salmon remains unknown, but consideration of the evolution and life history of the fish provides some clues as to the possible nature of the mechanism.

Normal fluctuations in the earth’s magnetic field influence pigeon orientation.

Homing pigeons are thought to use the earth’s magnetic field for direction finding. Though the sensory system and the characteristics of the magnetic field used are unknown, it can be hypothesized that pigeons have an inclination compass, as do some migratory birds.

Influence of low magnetic-field-strength variations on the retina and pineal gland of quail and humans.

Recently, Schulten postulated on the basis of his experiments and quantum-mechanical calculations that variations of the strength of the earth’s magnetic field may influence reactions in biological systems.

These observations were further supported by our examination of the influence of magnetic field variation on human night-vision acuity. Whereas the magnetic influence on the avian retina may be interpreted in connection with navigation, the importance for the human retina remains to be elucidated… (To be continued)

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