What would happen to the earth if there were NO magnetosphere?

Among the four rocky planets in our solar system, you could say that World's "magnetic" personality is the envy of her interplanetary neighbors.

Unlike Mercury, Venus, and Mars, Earth is surrounded past an immense magnetic field chosen the magnetosphere. Generated by powerful, dynamic forces at the center of our globe, our magnetosphere shields u.s. from erosion of our temper by the solar wind (charged particles our Lord's day continually spews at us), erosion and particle radiation from coronal mass ejections (massive clouds of energetic and magnetized solar plasma and radiation), and cosmic rays from deep space. Our magnetosphere plays the role of gatekeeper, repelling this unwanted energy that's harmful to life on World, trapping well-nigh of information technology a safety distance from Earth'south surface in twin doughnut-shaped zones called the Van Allen Belts.

Impacts of infinite weather. Credit: NOAA

But Earth'south magnetosphere isn't a perfect defence. Solar current of air variations tin disturb it, leading to "infinite weather" -- geomagnetic storms that can penetrate our atmosphere, threatening spacecraft and astronauts, disrupting navigation systems and wreaking havoc on power grids. On the positive side, these storms also produce World's spectacular aurora. The solar air current creates temporary cracks in the shield, assuasive some energy to penetrate down to Earth's surface daily. Since these intrusions are cursory, however, they don't cause significant problems.

This image of a colorful aurora was taken in Delta Junction, Alaska, on April 10, 2015. All auroras are created by energetic electrons, which rain down from Earth's magnetic bubble and interact with particles in the upper atmosphere to create glowing lights that stretch beyond the sky. Credit: Image courtesy of Sebastian Saarloos

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Because the forces that generate Earth's magnetic field are constantly changing, the field itself is also in continual flux, its strength waxing and waning over time. This causes the location of Earth's magnetic north and south poles to gradually shift and to completely flip locations almost every 300,000 years or and so. Y'all can larn why magnetic field polarity changes and shifts have no effect on climate on the timescales of human being lifetimes and aren't responsible for Earth'southward recent observed warming here.

Launched in Nov 2013 by the European Infinite Agency (ESA), the three-satellite Swarm constellation is providing new insights into the workings of Earth'southward global magnetic field. Generated by the motion of molten iron in Earth's core, the magnetic field protects our planet from cosmic radiation and from the charged particles emitted past our Sun. It as well provides the basis for navigation with a compass.

Based on data from Swarm, the top image shows the average strength of Earth's magnetic field at the surface (measured in nanotesla) between January 1 and June 30, 2014. The second image shows changes in that field over the aforementioned period. Though the colors in the second epitome are just as bright as the start, note that the greatest changes were plus or minus 100 nanotesla in a field that reaches 60,000 nanotesla. Credit: European Space Agency/Technical University of Denmark (ESA/DTU Space)

To understand the forces that drive Earth'due south magnetic field, it helps to commencement peel dorsum the 4 main layers of Earth's "onion" (the solid Earth):

1. The crust, where we live, which is nearly 19 miles (31 kilometers) deep on boilerplate on land and about iii miles (5 kilometers) deep at the body of water bottom.
2. The mantle, a hot, viscous mix of molten stone almost ane,800 miles (2,900 kilometers) thick.
3. The outer core, near one,400 miles (two,250 kilometers) thick and composed of molten iron and nickel.
4. The inner cadre, a roughly 759-mile-thick (ane,221-kilometer-thick) solid sphere of iron and nickel metals about as hot every bit the Lord's day'south surface.

Globe's internal construction: dense solid metallic core, viscous metallic outer core, pall and silicate-based chaff. Credit: NASA

Nearly all of World'south geomagnetic field originates in the fluid outer core. Like boiling water on a stove, convective forces (which motion heat from one identify to another, usually through air or water) constantly churn the molten metals, which also swirl in whirlpools driven by World'southward rotation. As this roiling mass of metallic moves around, it generates electric currents hundreds of miles wide and flowing at thousands of miles per hour as Earth rotates. This machinery, which is responsible for maintaining World's magnetic field, is known as the geodynamo.

Illustration of the dynamo mechanism that creates World's magnetic field: convection currents of fluid metal in Globe'due south outer core, driven past heat catamenia from the inner cadre, organized into rolls by the Coriolis force, create circulating electrical currents, which generate the magnetic field. Credit: Andrew Z. Colvin, CC BY-SA 4.0, via Wikimedia Commons

At Globe'due south surface, the magnetic field forms two poles (a dipole). The north and s magnetic poles have opposite positive and negative polarities, similar a bar magnet. The invisible lines of the magnetic field travel in a airtight, continuous loop, flowing into Earth at the due north magnetic pole and out at the south magnetic pole. The solar wind compresses the field'south shape on Earth'south Sun-facing side, and stretches it into a long tail on the dark-facing side.

The study of Earth's by magnetism is chosen paleomagnetism. Straight observations of the magnetic field extend back merely a few centuries, and so scientists rely on indirect evidence. Magnetic minerals in aboriginal undisturbed volcanic and sedimentary rocks, lake and marine sediments, lava flows and archeological artifacts tin reveal the magnetic field's strength and directions, when magnetic pole reversals occurred, and more. By studying global evidence and data from satellites and geomagnetic observatories and analyzing the magnetic field's development using estimator models, scientists tin construct a history of how the field has changed over geologic time.

A simple visualization of Earth's magnetosphere almost the time of the equinox. Credit: NASA's Scientific Visualization Studio

Earth is surrounded by a system of magnetic fields, called the magnetosphere. The magnetosphere shields our home planet from harmful solar and catholic particle radiation, but information technology tin can modify shape in response to incoming space weather from the Sun. Credit: NASA'southward Scientific Visualization Studio

Globe's mid-bounding main ridges, where tectonic plates form, provide paleomagnetists with data stretching dorsum about 160 million years. As lava continually erupts from the ridges, it spreads out and cools, and the iron-rich minerals in information technology align with the geomagnetic field, pointing north. Once the lava cools to about 1,300 degrees Fahrenheit (700 degrees Celsius), the strength and management of the magnetic field at that time become "frozen" into the rock. By sampling and radiometrically dating the rock, this record of the magnetic field can be revealed.

Studies of Globe's magnetic field have revealed much of its history.

Magnetic stripes around mid-ocean ridges reveal the history of Globe's magnetic field for millions of years. The study of World'south by magnetism is called paleomagnetism. Credit: USGS

For example, we know that over the past 200 years, the magnetic field has weakened about 9 percent on a global average. However, paleomagnetic studies bear witness the field is actually well-nigh the strongest it's been in the past 100,000 years, and is twice as intense as its million-yr average.

Nosotros too know there's a well-known "weak spot" in the magnetosphere that is present year-round. Located over South America and the southern Atlantic Body of water, the Due south Atlantic Anomaly (SAA) is an expanse where the solar air current penetrates closer to Globe'due south surface. It'due south created by the combined influences of the geodynamo and the tilt of Earth'south magnetic axis. While charged solar particles and cosmic ray particles within the SAA can fry spacecraft electronics, they don't affect life on World's surface.

We know the positions of World's magnetic poles are continually moving. Since it was showtime precisely located by British Regal Navy officeholder and polar explorer Sir James Clark Ross in 1831, the magnetic north pole's position has gradually drifted north-northwest past more than than 600 miles (one,100 kilometers), and its forward speed has increased, from about 10 miles (16 kilometers) per year to about 34 miles (55 kilometers) per year.

Earth's magnetic field acts like a protective shield around the planet, repelling and trapping charged particles from the Sun. Simply over South America and the southern Atlantic Ocean, an unusually weak spot in the field – called the S Atlantic Bibelot, or SAA – allows these particles to dip closer to the surface than normal. Currently, the SAA creates no visible impacts on daily life on the surface. However, recent observations and forecasts show that the region is expanding westward and continuing to weaken in intensity. The South Atlantic Anomaly is too of interest to NASA's Earth scientists who monitor the changes in magnetic strength there, both for how such changes impact Earth'south temper and as an indicator of what's happening to Earth's magnetic fields, deep inside the globe. Credit: NASA'south Scientific Visualization Studio

World'south magnetic poles are not the same as its geodetic poles, which nigh people are more familiar with. The locations of Earth's geodetic poles are determined by the rotational axis our planet spins upon. That axis doesn't spin evenly, similar a globe on your desk. Instead, information technology wobbles slightly. This causes the position of the truthful north pole to shift slightly over time. Numerous processes on Earth's surface and within its interior contribute to this wander, only it'south primarily due to the move of h2o around Earth. Since observations began, the position of Earth's rotational axis has drifted toward N America by most 37 feet (12 meters), though never more than almost 7 inches (17 centimeters) in a year. These wobbles don't affect our daily life, merely they must be considered to get authentic results from global navigation satellite systems, Earth-observing satellites and basis observatories. The wobbles can tell scientists about past climate conditions, simply they're a consequence of changes in continental water storage and ice sheets over time, not a cause of them.

Observed north dip poles during 1831 - 2007 are xanthous squares. Modeled pole locations from 1590 to 2020 are circles progressing from blue to yellowish.

Observed s dip poles during 1903 - 2000 are yellow squares. Modeled pole locations from 1590 to 2020 are circles progressing from blue to yellowish. Credit: NOAA/NCEI

Past far the most dramatic changes impacting Earth's magnetosphere are pole reversals. During a pole reversal, Earth'southward magnetic n and south poles swap locations. While that may sound like a big deal, pole reversals are actually mutual in Earth'southward geologic history. Paleomagnetic records, including those revealing variations in magnetic field forcefulness, tell united states World's magnetic poles accept reversed 183 times in the concluding 83 million years, and at least several hundred times in the by 160 million years. The time intervals between reversals have fluctuated widely, but average virtually 300,000 years, with the last taking place most 780,000 years ago. Scientists don't know what drives pole reversal frequency, only information technology may be due to convection processes in Earth's mantle.

Positions of Earth'due south Northward Magnetic Pole. Poles shown are dip poles, defined as positions where the direction of the magnetic field is vertical. Red circles mark magnetic north pole positions as determined by direct ascertainment; blue circles mark positions modelled using the GUFM model (1590–1890) and the IGRF-12 model (1900–2020) in one-year increments. For the years 1890–1900, a polish interpolation between the two models was performed. The modelled locations after 2015 are projections. Credit: Cavit, CC Past 4.0, via Wikimedia Commons

During a pole reversal, the magnetic field weakens, simply information technology doesn't completely disappear. The magnetosphere, together with Globe's temper, nonetheless continue to protect our planet from catholic rays and charged solar particles, though there may be a small-scale amount of particulate radiations that makes information technology down to World's surface. The magnetic field becomes jumbled, and multiple magnetic poles tin can emerge at unexpected latitudes.

World does not always spin on an axis running through its poles. Instead, it wobbles irregularly over fourth dimension, drifting toward North America throughout virtually of the 20th Century (green arrow). That direction has inverse drastically due to changes in water mass on Earth. Credit: NASA/JPL-Caltech

Earlier well-nigh 2000, Globe's spin axis was drifting toward Canada (green pointer, left globe). JPL scientists calculated the consequence of changes in water mass in different regions (center globe) in pulling the direction of drift eastward and speeding the rate (right globe). Credit: NASA/JPL-Caltech

The relationship between continental water mass and the eastward-due west wobble in World'south spin axis. Losses of water from Eurasia correspond to eastward swings in the full general direction of the spin axis (top), and Eurasian gains button the spin axis westward (bottom). Credit: NASA/JPL-Caltech

No one knows exactly when the side by side pole reversal may occur, but scientists know they don't happen overnight. Instead, they take identify over hundreds to thousands of years. Scientists have no reason to believe a flip is imminent.

Geomagnetic polarity over the past 169 meg years, abaft off into the Jurassic Tranquillity Zone. Dark areas denote periods of normal polarity, light areas denote reverse polarity. Credit: Public domain

Supercomputer models of Earth'southward magnetic field. On the left is a normal dipolar magnetic field, typical of the long years between polarity reversals. On the right is the sort of complicated magnetic field Earth has during the upheaval of a reversal. Credit: University of California, Santa Cruz/Gary Glatzmaier

Finally, there are "geomagnetic excursions:" shorter-lived but significant changes to the intensity of the magnetic field that last from a few centuries to a few tens of thousands of years. Excursions happen about 10 times as frequently as pole reversals. An excursion can re-orient Earth's magnetic poles as much as 45 degrees from their previous position, and reduce the strength of the field by up to 20 percent. Circuit events are generally regional, rather than global. At that place have been three significant excursions in the past 70,000 years: the Norwegian-Greenland Sea event about 64,500 years ago, the Laschamps effect between 42,000 and 41,000 years agone, and the Mono Lake result almost 34,500 years ago.

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Source: https://climate.nasa.gov/news/3105/earths-magnetosphere-protecting-our-planet-from-harmful-space-energy/

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