A magnet tends to produce an area of influence around itself that’s not visible to the naked eye and these invisible influences are called ‘fields’.Scientists even study these fields and their presence in outer space. These magnetic fields are very much visible on the nearest star to Earth, the sun, as they are emitted from the surface of the sun.Earth is enveloped by the atmosphere and its strongest shield, the magnetic field. Earth’s magnetic field is why we see many beautiful phenomena, such as the Northern lights, which are aurora dancing in the skies due to the south and north poles’ magnetic field. This field is also responsible for protecting us from really dangerous cosmic rays and particles such as the solar particles coming from the sun. But how do you go about interpreting and understanding something that you can’t even see?Well, the answer is simple. You can’t see air, can you? Yet you still understand its behavior. Similarly, humans have used several real-life applications of the field in navigation, mostly to understand it. For centuries people relied on directions provided by a magnetic compass which uses a magnetic field. Nowadays, scientists have determined ways to define the intensity of certain points on Earth’s surface that have a strong magnetic field; they can also use it to determine the field’s orientation.Keep reading this article to understand the different aspects of Earth’s magnetic field, what causes it, what are some of the most important phenomena associated with it, how it is vital to life, and many more fun facts that you may not already know! So go ahead and put on your science cap as we delve into one of the most intriguing topics for scientists; Earth’s magnetic field!Types Of MagnetismMagnets are not just limited to the ones on your refrigerator! The planet on which we are living produces a magnetic field that behaves similarly to a magnetic dipole. The south pole or the magnetic south pole of the field is actually near the geographic north pole, while the magnetic north pole is actually found near the geographic south pole of Earth. Earth’s magnetic field is akin to a bar magnet’s field and the liquid inside Earth’s outer core has electric currents that actually cause Earth’s magnetic field. This reason for Earth’s magnetic field can also be explained by the dynamo theory, which also enables the use of a compass in navigation. The electric currents caused in Earth’s outer core are explained by the Coriolis effect, convection of molten iron, and planetary rotation as well. These currents are usually aligned along the north-south polar axis.There are in general five types of magnetism, namely; ferromagnetism, antiferromagnetic, paramagnetism, ferrimagnetism, and diamagnetism. The criterion for classification is the kind of magnetic behavior of any material at different temperatures with respect to any nearby magnetic field.There exist two types of poles for any magnet: a south pole and a north pole. The two poles are the endpoints of the magnetic field as it flows from the north pole to the south pole. Earth’s magnetic field also has its respective north and south poles.Earth’s magnetic field is also known as the geomagnetic field, which extends tens of thousands of kilometers into space! Although it starts weakening from its source the further it gets. This infinite space of field forms Earth’s magnetosphere. An Australian study found this field to be almost 3.5 billion years old!Did you know that the temperature inside Earth’s core is 5200 C (9392 F)? This is also the temperature that causes the randomization of spin orientations within an iron. This kind of randomization inside a substance causes it to lose its magnetization.ElementsEarth’s magnetic field has played a very important part, along with water and oxygen, to sustain life on Earth. The field not only interferes with a compass needle but also deflects the harmful solar winds that could otherwise destroy the atmosphere of the planet. So what are the elements of this field? Let’s find out.The major elements making up the field are magnetic declination, an angle between the geographical and magnetic axis. This magnetic inclination is the dip angle made by the compass needle with the horizontal and this angle varies with Earth’s surface. Lastly, the horizontal component is the horizontal component of Earth’s magnetic field.When we talk about defining a magnetic field, there are two very important parts; the magnetic poles and magnetic dipoles.The position of magnetic poles can be looked upon in two ways. Firstly, the magnetic pole is described to be a point where the magnetic field is completely vertical on Earth’s surface. Earth’s field is found to be 90 degrees at the north magnetic pole and the south pole.Sometimes it could be found that a magnetic compass at one of the magnetic poles will point randomly to the north magnetic pole or somewhere away from the south magnetic pole when held horizontally. That’s because these poles keep wandering and therefore are not really located opposite each other. It is said that these poles can migrate to up to 24.85 mi (40 km) per year!Secondly, the field from a magnetic dipole helps estimate the magnetic field’s position. However, this dipole should be located somewhere around the center of Earth. An axis defines a dipole’s orientation and the positions or endpoints where the axis of the dipole best fits are termed as south and north geomagnetic poles.To find the best fitting dipole that would represent the geomagnetic field, it should be placed 310.68 mi (500 km) away from the center of Earth. The reason for this is to lower the inner radiation belt in the southern Atlantic ocean, where Earth’s surface field is weakest. This would also result in the south Atlantic anomaly.Did you ever think about how exactly the magnetic field came into existence? Well, with the resources available today, scientists think that the magnetic field around Earth is a result of the solidification of the liquid iron core present inside Earth. What possibly happened is that the crystallization and cooling of the core around the liquid iron will have resulted in the formation of intense electric currents that generated a magnetic field reaching far and beyond in space. This magnetic field was termed a geodynamo.Our magnetic field is about 3.5 billion years old, but surprisingly our planet started solidifying just 1 billion years ago. This implies that Earth’s magnetic field must be driven by something other than Earth. Well, scientists are still figuring that out, and discovering when the magnetic field was first created would lead to the answer of what it is really made of.Finding what the magnetic field is made of can also lead us to how and when life first occurred on this planet.Shape Of Magnetic FieldThe current convection present in Earth’s core generates the massive magnetic field around the planet enveloping it safely from the sun’s harmful charged particles. However, this magnetic field does not remain the same and can change its direction from time to time, although the interval may be millions of years! These geomagnetic reversals and other geomagnetic field variations are recorded from old rocks. However, the real theory behind occurrences of these geomagnetic reversals is still not clear. Some geologists and scientists created models of the magnetic field where the poles could move from one orientation to the other. They found the field is quasi-stable; this simulated the real phenomenon of geomagnetic reversals. But a key fact remains unanswered: What is this magnetic field’s shape like? Let’s look at the answer.The shape of the geomagnetic field is akin to the field created by a bar magnet. The south and north poles represent the polarities of the field and the magnetic lines flow between these poles, encircling the planet as they flow. There is, however, a key difference between the shape of Earth’s magnetic field and a bar magnet’s magnetic field; the core field is not stable and is not aligned throughout the world.Earth’s magnetic field should, however, remain as stable as possible because it is integral to the survival of the planet. Not just to protect us from geomagnetic storms that can increase the solar wind but also because an unstable magnetic field can result adversely on our technology. Our smartphones would probably stop working because there would be disruption in power grids, locations would not be identified correctly, and navigation and satellite systems would collapse. Not to mention our increased vulnerability to several solar storm events happening in space.Do you know why magnetic storms are caused in the first place? The sun’s mass ejection of solar wind is the primary reason. A gust of solar wind disrupts Earth’s magnetic field’s outer region, thereby almost oscillating it. Solar wind is basically an outflow of magnetic fields and particles known collectively as solar wind. Enormous clouds of hot radiation and plasma, known as coronal mass ejections, are also expelled from the sun’s surface. These ejections collide with Earth’s magnetosphere, but Earth’s field acts as a shield to protect us from these harmful radiations. The ozone layer is also a part of this protective shield that prevents harmful ultraviolet radiation from reaching us. Still, nowadays, we often hear about the depletion of the ozone layer due to excessive human activities. Now, this is a serious cause of concern. If we completely deplete the ozone layer we will become highly at risk of exposure to ultraviolet radiation.The magnetosphere is defined officially as the region above the ionosphere that contains the extent of Earth’s magnetic field stretching out in space. This region stretches out miles and miles across space to protect the planet from any object in space that could eject harmful cosmic rays or solar winds, which could tear away our upper atmosphere.Before, the north and south poles were described as the magnetic field of Earth and not vice versa, as it is done today. This was because the very first application of a magnet was for a compass needle.Several magnetic phenomena like geomagnetic storms directly impact our lives, like disrupting GPS systems (imagine if you were to reach a wrong destination at the most critical time!), electric power grids, radio communication, oil and gas drilling, and the operation of other satellites. In fact, even traveling from airplanes would get difficult as astronauts and pilots are exposed to enhanced levels of magnetic radiation at high altitudes.Certain geomagnetic observatories such as the Eskdalemuir Observatory of the British Geological Survey, a part of a national geological survey, or forecast, measure all the effects of magnetic storms, which have the potential to affect electric power, communications, and other necessary human activities.Fun Facts About Earth’s Magnetic FieldThere’s so much to know about magnetic poles. You would be amazed to know all about magnetic fields, magnetic storms, geomagnetic reversals, and other magnetic phenomena! So read some of these fun facts about Earth’s field below.Different planets have magnetic fields around them whose behavior is just like that of the bar magnet.The magnetic properties of metals are lost at high temperatures. Thus, it implies that Earth’s core does not power the magnetic field around the planet; instead, the dynamo effect causes the magnetic field around Earth’s surface.The dynamo effect does not hold true on the surface of Mars as Mars lacks liquid metal flow in its core.Therefore, the magnetic field around Mars is quite weak, resulting in solar winds ripping away the planet’s atmosphere, which makes Mars uninhabitable.The temperature of Earth’s inner core is over 9032 F (5000 C)! This very heat drives convection currents in Earth’s fluid present in Earth’s outer core. As Earth rotates, these currents form into columns for their motion.The outer part of Earth’s core is always in a turbulent condition due to chemical differentiation and radioactive heating. These conditions are somewhat similar to an electrical generator that converts convective kinetic energy to magnetic and electrical energy.Scientists today have found evidence of how the early solar system harbored a gap between its outer and inner regions. The cosmic boundary of these regions is traced to some emerging wind or Jupiter that shaped the other infant planets as well.A three-dimensional structure of Earth was mapped by the MagSat satellite. Still, the later satellites have taken the help of three-axis vector magnetometers to develop the 3D structure of Earth’s magnetic field. Another satellite by the name of Orsted also made it possible to conduct comparison experiments to find out about an alternate pole in the Atlantic ocean. The government has implemented special operating units to measure and analyze Earth’s magnetic field.Since 1991 the International Real-time Magnetic Observatory Network has been recording Earth’s magnetic field with the help of 100 other geomagnetic observatories worldwide. The military forces have also come into the picture to detect anomalies in local geomagnetic fields. These anomalies could aid in detecting problems for a submerged submarine.There are also airborne magnetic anomaly detectors that use magnetic instruments to detect submarines by mapping magnetic variations across the ocean floor. This technique was also used in the Second World War.Magnetic detectors are used not just for Earth’s magnetic field but also to identify anomalies from ores such as the Kursk Magnetic Anomaly.Were you aware that animals like turtles and a few birds possess the ability to detect Earth’s magnetic field and can use it to help them navigate during migration?The magnetic reversal is a significant phenomenon with respect to Earth’s field of magnetism. As the name suggests, the two poles of the magnetic field flip from one hemisphere to the other, and a temporary dipole tilt takes place across the dipole axis present on the equator. Studies show that lava flows from mountains during this reversal, and the shift of magnetic field can be accounted to around 6 degrees per day.Such fluctuations and changes in Earth’s magnetic field keep taking place and these changes affect us all in some way or another. For instance, the magnetic north pole is wandering, which could imply an impending change in Earth’s current magnetic field. However, a major reversal is not expected for millions of years to come.Did you know that a magnetic compass needle doesn’t necessarily point towards the northern magnetic pole? Yes, this is absolutely true, and it is because of another phenomenon called magnetic declination. This points to the deviation faced by the compass needle from the northern magnetic pole. This led to frustration amongst many navigators in old times as it did not give accurate geographical location at that time. Earth’s magnetic field is complex and interesting. Hopefully, you now know much more about what it means and the impact it has on the planet.
A magnet tends to produce an area of influence around itself that’s not visible to the naked eye and these invisible influences are called ‘fields’.
