Archiv: solares interplanetares Magnetfeld / Heliosphäre / solar interplanetary magnetic field / heliosphere / heliospheric current sheet


26.04.2024 - 01:30 [ PRI.org ]

Scientists link Earth’s magnetic reversals to changes in planet’s life and climate

(April 19, 2021)

The researchers examined the rings of the tree to look for changes in the amount of carbon-14 over a period of years, Gramling explains. Carbon-14 is useful not only for dating things, but because the interaction of cosmic rays with molecules in the atmosphere produces a lot of it. And when the Earth has a weakened magnetic field, more cosmic rays hit the planet.

The scientists indeed found a large spike in carbon-14 in the tree, which they could then compare with the rock record that indicated a magnetic reversal. (…)

In addition, there is the documented rise in cave art right about 41,000-42,000 years ago, Gramling points out.

26.04.2024 - 00:00 [ Journal of Geophysical Research: Solid Earth / onlinelibrary.wiley.com ]

Possible Eoarchean Records of the Geomagnetic Field Preserved in the Isua Supracrustal Belt, Southern West Greenland

(24 April 2024)

The preservation of a temperate climate and liquid water on early Earth depends critically upon the strength of the magnetosphere (Sterenborg et al., 2011; Tarduno et al., 2014). Recent atmospheric escape models have suggested that both weak (<10 μT) and strong (>1 mT) magnetic fields could substantially enhance atmospheric escape under present-day solar wind conditions via the polar wind or cusp escape, respectively (Gronoff et al., 2020; Gunell et al., 2018; Lundin et al., 2007). During the Archean, the Sun was rotating faster, generating a stronger stellar dynamo and therefore the solar wind was more intense than today (Vidotto, 2021). An increased solar wind strength causes greater interaction with the upper atmosphere and greater escape of ions assuming a constant level of protection from Earth‘s magnetosphere. Previous magnetohydrodynamic simulations have suggested that if Earth‘s magnetic field was half its present day strength 3.5 Ga ago, the area of the polar cap (the area containing open dipolar magnetic field lines, allowing atmospheric escape via the polar wind) could increase by up to 50% (Sterenborg et al., 2011).

25.04.2024 - 23:52 [ IFLscience.com ]

The Earth’s Magnetic Field Is At Least 3.7-Billion-Years Old, New Evidence Shows

The age of the Earth’s magnetic field remains under question in part because we don’t fully understand what causes it today. We know it is a product of movements in the molten outer core, whose high iron content turns convection currents into a dynamo, and these currents in turn are produced by the solidification of the inner core.

25.04.2024 - 23:45 [ livescience.com ]

Earth‘s magnetic field formed before the planet‘s core, study suggests

(24 April 2024)

Today, the magnetic field is driven by the churning of the liquid part of the core and the transfer of heat from the solid inner core to the convective outer core as the former cools. But researchers think the core didn‘t solidify until about a billion years ago.

14.06.2023 - 13:08 [ NASA New Horizons / Twitter ]

#OTD in 2019, @NASA‘s #NewHorizons flew by Arrokoth, the farthest object ever explored by spacecraft. Arrokoth is about about 50 AU, or 4 billion miles from the Sun. New Horizons is ~56 AU from Earth and will join Voyagers 1 & 2 in interstellar space in the 2040s.

14.06.2023 - 12:59 [ Youtube ]

5 Spacecraft Are Leaving The Solar System. What Did They See In Their Journey?

Pioneer 10: Pioneer 10 was launched in 1972 to explore the planets of the solar system. It achieved the first flyby of Mars, the first trip through the asteroid belt, and Jupiter‘s first flyby. It was the first time NASA had used nuclear energy to power its spacecraft. So, after Pioneer 10 passed Jupiter in 1973, it still had ample energy to keep going. Initially planned for 21 months, it continued to communicate with Earth for a total of 30 years.

14.06.2023 - 12:50 [ Space.com ]

What Spacecraft Will Enter Interstellar Space Next?

(January 30, 2019)

This milestone — reaching interstellar space — can be considered leaving the solar system by a certain definition. Let‘s be clear about what that entails. In 1990, the New York Times reported that Pioneer was reported to leave the solar system when it flew past Neptune‘s orbit. That‘s not what Voyager 2‘s scientists used to make their determination, however. Instead, the more recent measurements consider the crossing of the sun‘s heliopause, the theoretical boundary to its heliosphere, to be the determining factor for entering interstellar space. The heliosphere is a bubble of charged particles created by and flowing past the sun. Scientists use it to mark where interstellar space begins.

14.06.2023 - 12:47 [ ORF.at ]

Raumsonde „Pioneer 10“ 40 Jahre aus Sonnensystem heraus

Am 13. Juni 1983 durchflog „Pioneer 10“ die Umlaufbahn des Neptun und wurde so laut NASA zum ersten menschengemachten Raumschiff, das am weitestentfernten bekannten Planeten unseres Sonnensystems vorbeiflog. Neptun ist im Mittel etwa 4,5 Milliarden Kilometer von der Sonne entfernt.

Mit „Pioneer 11“ und den beiden „Voyager“-Sonden folgten später ähnliche Missionen. „Voyager 1“ überholte „Pioneer 10“ schließlich als am weitesten von der Erde entferntes menschengemachtes Objekt. Zum bisher letzten Mal schickte „Pioneer 10“ im Jänner 2003 Daten, ein Kontaktversuch im März 2006 scheiterte.

24.04.2023 - 11:25 [ Times of India ]

Study: Sun’s magnetic field is weakening

(Oct 7, 2019)

The research, according to the team, will help monitor and evaluate the influence of solar activities and their implications on the Earth’s climate. The astrophysicists’ team included experts from Ahmedabad’s Physical Research Laboratory (PRL), Japan, and China.

24.04.2023 - 10:52 [ International Association of Geomagnetism and Aeronomy (IAGA) / Cairo University ]

The Shrinking of the Heliosphere Due to Reduced Solar Wind

(2010)

Abstract. The heliosphere is the space within which the solar wind dominates and the solar interplanetary magnetic field prevails. Its boundary is determined by the balance between stellar and solar winds. Owing to the present reduction in the solar wind pressure, one would expect that the stellar wind would push the heliosphere inward leading to its shrinkage. In this paper we calculate the extent of the heliosphere at different solar wind status.

Backward estimation of the extent of the heliosphere since 1890 is done. It is found that the heliosphere oscillated between 75 and 125 AU between 1890 –
2010. Most important is the forecast of the shrinkage and oscillations of the heliosphere and their implications on the earth. The shrinkage of the heliosphere would allow more invasions of cosmic rays to the earth and planets, increased cloud cover and a cooler Earth.

1 Introduction

The heliosphere is the cavity curved by the solar wind into the interstellar medium. Its extension is determined by the equality of the solar wind pressure and the stellar wind pressure. For this reason, we will first study past, present and future status of solar activity and then we will reflect this study into the heliosphere.

24.04.2023 - 10:51 [ Telegraph.co.uk ]

Sun‘s protective ‚bubble‘ is shrinking

(18.10.2008)

New data has revealed that the heliosphere, the protective shield of energy that surrounds our solar system, has weakened by 25 per cent over the past decade and is now at it lowest level since the space race began 50 years ago. (…)

„Around 90 per cent of the galactic cosmic radiation is deflected by our heliosphere, so the boundary protects us from this harsh galactic environment.“

The heliosphere is created by the solar wind, a combination of electrically charged particles and magnetic fields that emanate a more than a million miles an hour from the sun, meet the intergalactic gas that fills the gaps in space between solar systems.

26.12.2022 - 06:31 [ Electroverse.co ]

Cold Records Shattered Across Canada, Driving Energy Usage To All-Time Highs; Extreme Freeze Sweeps U.S.; Blizzards Hit Hawaii; + Wintry Weather Traps 300 Oil Workers On North Sea Rig

(December 21, 2022)

As hinted at above, Mauna Loa began erupting on Nov 27 and stopped on Dec 13.

It was the first time it has actively erupted since 1984 (solar minimum of cycle 20) — and is a sign of the times…

Volcanic eruptions are one of the key climatic forcings driving Earth into its next bout of global cooling. They have been shown to increase in both number and explosivity during times of prolonged solar decline, which is thought to be due to an influx of cosmic rays (CRs) penetrating/exciting silica-rich magma. During solar mins the Sun’s magnetic field weakens and the outward pressure of the solar wind decreases, which allows more CRs to enter the inner solar system, including our planet’s atmosphere.

14.11.2021 - 14:00 [ Nature.com ]

Solar differential rotation reproduced with high-resolution simulation

(Published: 13 September 2021)

Here, we show that a high-resolution calculation succeeds in reproducing the solar-like differential rotation. Our calculations indicate that the strong magnetic field generated by a small-scale dynamo has a significant impact on thermal convection. The successful reproduction of the differential rotation, convection and magnetic field achieved in our calculation is an essential step to understanding the cause of the most basic nature of solar activity, specifically, the 11 yr cycle of sunspot activity.

14.11.2021 - 12:24 [ EOS.org ]

Accurate Simulation of Sun’s Rotation Might Illuminate Solar Cycle

(08.11.2021)

Japanese scientists said they have created the first accurate computer simulation of how the Sun rotates, reproducing a phenomenon in which its equatorial area spins faster than its polar regions. The insight could help explain the whys and hows of the solar cycle, one of the biggest mysteries of our star.

25.10.2021 - 19:22 [ arxiv.org ]

A Unified Model for the Fan Region and the North Polar Spur: A bundle of filaments in the Local Galaxy

We present a simple, unified model that can explain two of the brightest, large-scale, diffuse, polarizedradio features in the sky, the North Polar Spur (NPS) and the Fan Region, along with several otherprominent loops. We suggest that they are long, magnetized, and parallel filamentary structures thatsurround the Local arm and/or Local Bubble, in which the Sun is embedded. We show this modelis consistent with the large number of observational studies on these regions, and is able to resolvean apparent contradiction in the literature that suggests the high latitude portion of the NPS isnearby, while lower latitude portions are more distant. Understanding the contributions of this localemission is critical to developing a complete model of the Galactic magnetic field.

25.10.2021 - 19:18 [ Dunlap Institute for Astronomy & Astrophysics, University of Toronto ]

Dunlap Astronomer discovers we may be surrounded by tunnel-like structure

(Oct.14, 2021)

Dr. Jennifer West, Research Associate at the Dunlap Institute for Astronomy and Astrophysics, is making a scientific case that two bright structures that are seen on opposite sides of the sky – previously considered to be separate – are actually connected and are made of rope-like filaments. This connection forms what looks like a tunnel around our solar system.

“If we were to look up in the sky,” explains West, “we would see this tunnel-like structure in just about every direction we looked – that is, if we had eyes that could see radio light.”

25.10.2021 - 19:10 [ SciTechdaily.com ]

A Vast “Magnetic Tunnel” May Surround Earth and Our Entire Solar System

(today)

An expert in magnetism in galaxies and the interstellar medium, West looks forward to the more possible discoveries connected to this research.

“Magnetic fields don’t exist in isolation,” she says. “They all must to connect to each other. So, a next step is to better understand how this local magnetic field connects both to the larger-scale galactic magnetic field, and also to the smaller scale magnetic fields of our sun and Earth.”

25.10.2021 - 18:59 [ National Aeronautics and Space Administration ]

Studying the Edge of the Sun’s Magnetic Bubble

(Oct 19, 2021)

The space radiation that comes at us from other stars is called galactic cosmic radiation (GCR). Active areas in the galaxy – like supernovae, black holes, and neutron stars – can strip the electrons from atoms and accelerate the nuclei to almost the speed of light, producing GCR.

On Earth, we have three layers of protection from space radiation. The first is the heliosphere, which helps block GCR from reaching the major planets in the solar system. Additionally, Earth’s magnetic field produces a shield called the magnetosphere, which keeps GCR out away from Earth and low-orbiting satellites like the International Space Station. Finally, the gases of Earth’s atmosphere absorb radiation.

25.10.2021 - 18:48 [ National Aeronautics and Space Administration ]

With NASA Data, Researchers Find Standing Waves at Edge of Earth’s Magnetic Bubble

(Oct.6, 2021)

The latest work considers the waves that form across the entire surface of the magnetosphere, using a combination of models and observations from NASA’s THEMIS mission, Time History of Events and Macroscale Interactions during Substorms.

The researchers found when solar wind pulses strike, the waves that form not only race back and forth between Earth’s magnetic poles and the front of the magnetosphere, but also travel against the solar wind. Archer likened these two kinds of movement to crossing a river: A boat can go from one riverbank to the other (traveling towards the poles) and upstream (against the solar wind). At the front of the magnetosphere, these waves appear to stand still.

25.10.2021 - 18:30 [ Electroverse.net ]

Solar Cycle 25 Progressing Similarly to 24, + Fairbanks sees Record-Breaking Snowfall

(October 6, 2021)

The official forecast by the NOAA/NASA Solar Cycle 25 Prediction Panel (made in 2019, and visualized by the red line above) called for a weak cycle 25, peaking in July 2025. And while things are currently tracking slightly ahead of schedule, NOAA don’t believe that the cycle will peak any higher than SC24. Instead, they simply see the peak arriving earlier, in late-2024 (rather than mid-2025). If this plays out it would of course mean an earlier start to Solar Cycle 26, too …

25.10.2021 - 18:04 [ Times of India ]

Study: Sun’s magnetic field is weakening

(Oct 7, 2019)

The research, according to the team, will help monitor and evaluate the influence of solar activities and their implications on the Earth’s climate. The astrophysicists’ team included experts from Ahmedabad’s Physical Research Laboratory (PRL), Japan, and China.

25.10.2021 - 17:25 [ Forbes.com ]

Is Earth’s Magnetic Shield Eroding?

(29.3.2018)

The strength of Earth’s main magnetic field is currently about 29.5 microteslas, down 5 microteslas, or 14 percent from its strength three centuries ago.

We know this. There is no question of this.

25.10.2021 - 17:04 [ PRI.org ]

Scientists link Earth‘s magnetic reversals to changes in planet‘s life and climate

(April 19, 2021)

The researchers examined the rings of the tree to look for changes in the amount of carbon-14 over a period of years, Gramling explains. Carbon-14 is useful not only for dating things, but because the interaction of cosmic rays with molecules in the atmosphere produces a lot of it. And when the Earth has a weakened magnetic field, more cosmic rays hit the planet.

The scientists indeed found a large spike in carbon-14 in the tree, which they could then compare with the rock record that indicated a magnetic reversal. (…)

In addition, there is the documented rise in cave art right about 41,000-42,000 years ago, Gramling points out.

04.10.2021 - 07:23 [ Astronomy.com ]

When north goes south: Is Earth‘s magnetic field flipping?

(September 14, 2021)

Something odd is happening to Earth’s magnetic field. Over the last 200 years, it’s been slowly weakening and shifting its magnetic north pole (where a compass points, not to be confused with the geographic north pole) from the Canadian Arctic toward Siba. In recent decades, however, that slow shift south has quickened — reaching speeds upwards of 30 miles per year (48 kilometers per year).

04.10.2021 - 07:04 [ National Astronomical Observatory of Japan / SciTechdaily.com ]

Interplay Between Magnetic Force and Gravity in Massive Star Formation

(September 26, 2021)

The magnetic field is part of one of the four fundamental forces in nature. It plays a vital role in everyday life, from producing electricity in hydroelectric power plants to diagnosing diseases in medicine. Historically, the Earth’s magnetic field served as a compass for travelers before modern technology was available. Crucially for life, the Earth’s magnetic field acts as a shield protecting us from charged particles emanating from the Sun, which are accelerated by the Sun’s magnetic field. Removing this shield would very likely extinguish life on Earth.

04.10.2021 - 05:51 [ Forbes.com ]

Is Earth’s Magnetic Shield Eroding?

(29.3.2018)

The strength of Earth’s main magnetic field is currently about 29.5 microteslas, down 5 microteslas, or 14 percent from its strength three centuries ago.

We know this. There is no question of this.

20.09.2021 - 05:45 [ PRI.org ]

Scientists link Earth‘s magnetic reversals to changes in planet‘s life and climate

(April 19, 2021)

The researchers examined the rings of the tree to look for changes in the amount of carbon-14 over a period of years, Gramling explains. Carbon-14 is useful not only for dating things, but because the interaction of cosmic rays with molecules in the atmosphere produces a lot of it. And when the Earth has a weakened magnetic field, more cosmic rays hit the planet.

The scientists indeed found a large spike in carbon-14 in the tree, which they could then compare with the rock record that indicated a magnetic reversal. (…)

In addition, there is the documented rise in cave art right about 41,000-42,000 years ago, Gramling points out.

10.08.2021 - 10:48 [ PRI.org ]

Scientists link Earth‘s magnetic reversals to changes in planet‘s life and climate

(April 19, 2021)

The researchers examined the rings of the tree to look for changes in the amount of carbon-14 over a period of years, Gramling explains. Carbon-14 is useful not only for dating things, but because the interaction of cosmic rays with molecules in the atmosphere produces a lot of it. And when the Earth has a weakened magnetic field, more cosmic rays hit the planet.

The scientists indeed found a large spike in carbon-14 in the tree, which they could then compare with the rock record that indicated a magnetic reversal. (…)

In addition, there is the documented rise in cave art right about 41,000-42,000 years ago, Gramling points out.

15.07.2021 - 09:24 [ PRI.org ]

Scientists link Earth‘s magnetic reversals to changes in planet‘s life and climate

(April 19, 2021)

The researchers examined the rings of the tree to look for changes in the amount of carbon-14 over a period of years, Gramling explains. Carbon-14 is useful not only for dating things, but because the interaction of cosmic rays with molecules in the atmosphere produces a lot of it. And when the Earth has a weakened magnetic field, more cosmic rays hit the planet.

The scientists indeed found a large spike in carbon-14 in the tree, which they could then compare with the rock record that indicated a magnetic reversal. (…)

In addition, there is the documented rise in cave art right about 41,000-42,000 years ago, Gramling points out.

15.07.2021 - 09:03 [ ScienceAlert.com ]

Earth‘s Magnetic Field Could Be Changing Much Faster Than We Ever Realised

(8 JULY 2020)

Past palaeomagnetic studies have shown that the magnetic field could change direction at up to 1 degree a year, but the latest study suggests that movements of up to 10 degrees annually are possible.

15.07.2021 - 08:54 [ Forbes.com ]

Is Earth’s Magnetic Shield Eroding?

(29.3.2018)

The strength of Earth’s main magnetic field is currently about 29.5 microteslas, down 5 microteslas, or 14 percent from its strength three centuries ago.

We know this. There is no question of this.

15.07.2021 - 08:30 [ University of Maryland / ScienceDaily.com ]

Space mission first to observe key interaction between magnetic fields of Earth and sun

Date: May 12, 2016

Source: University of Maryland

Summary: Physicists have now provided the first major results of NASA‘s Magnetospheric Multiscale (MMS) mission, including an unprecedented look at the interaction between the magnetic fields of Earth and the sun. The article describes the first direct and detailed observation of a phenomenon known as magnetic reconnection, which occurs when two opposing magnetic field lines break and reconnect with each other, releasing massive amounts of energy.

15.07.2021 - 08:10 [ NationalGeographic.com ]

Surprise: Solar System „Force Field“ Shrinks Fast

(October 1, 2010)

It‘s cold, dusty, and bereft of planets, but the outskirts of our solar system are anything but dull, according to increasing evidence from NASA‘s Interstellar Boundary Explorer (IBEX) craft.

As charged particles flow out from the sun, they eventually bump up against interstellar medium—the relatively empty areas between stars. These interactions „inflate“ a protective bubble that shields Earth and the entire solar system from potentially harmful cosmic rays (solar system pictures).

15.07.2021 - 08:01 [ Massachusetts Institute of Technology (MIT) ]

The solar wind bubble that protects Earth has been mapped for the first time

Using data IBEX collected on ENAs as it charted just one 11-year solar cycle, the time between shifts in the sun’s magnetic field, researchers built a three-dimensional map of the entire heliosphere, which Reisenfeld says shields Earth and other planets from harmful radiation.

“Our Earth gets bombarded by cosmic rays, galactic cosmic rays all the time,” he says. These rays can subtly affect airplanes that fly near the poles, often on trips between Europe or Asia and the US.

Scientists say that to study other planet’s astrospheres, which is what heliospheres are called when they surround other stars, we must first understand our own.

21.02.2021 - 13:05 [ ScienceNews.org ]

50 years ago, scientists named Earth’s magnetic field as a suspect in extinctions

(November 19, 2020)

Effects of Earth’s magnetic field — Science News, November 21, 1970

„Earth’s magnetic field has frequently reversed at intervals of 1 million to 100 million years. A few scientists now suspect that these reversals may have had drastic effects on terrestrial life.… During the past 2.5 million years, eight species of one-cell marine animals called Radiolaria became extinct. Six of these extinctions occurred simultaneously throughout their geographic range immediately following magnetic reversals.“

21.02.2021 - 12:40 [ Science Magazine ]

A global environmental crisis 42,000 years ago

(19.02.2021)

We find that geomagnetic field minima ~42 ka, in combination with Grand Solar Minima, caused substantial changes in atmospheric ozone concentration and circulation, driving synchronous global climate shifts that caused major environmental changes, extinction events, and transformations in the archaeological record.

21.02.2021 - 12:35 [ CNN ]

Reversal of Earth‘s magnetic poles may have triggered Neanderthal extinction — and it could happen again

(19.02.2021)

Some 42,000 years ago, in an event known as the Laschamp Excursion, the poles did just that for around 800 years, before swapping back — but scientists were unsure exactly how or if it impacted the world.

Now, a team of researchers from Sydney‘s University of New South Wales and the South Australian Museum say the flip, along with changing solar winds, could have triggered an array of dramatic climate shifts leading to environmental change and mass extinctions.

21.02.2021 - 03:32 [ NASA.gov ]

NASA Missions Make Unprecedented Map of Sun’s Magnetic Field

They’ll have a chance to take that step forward soon: A re-flight of the mission was just greenlit by NASA. Though the launch date isn’t yet set, the team plans to use the same instrument but with a new technique to measure a much broader swath of the Sun.

“Instead of just measuring the magnetic fields along the very narrow strip, we want to scan it across the target and make a two-dimensional map,” McKenzie said.

14.12.2020 - 17:11 [ mprnews.org ]

Solar storm fizzles, but ‚Solar Cycle 25‘ is just starting

„The panel believes that new Solar Cycle 25 will be a weak one, peaking in 2025 at levels similar to old Solar Cycle 24. If their prediction is correct, Solar Cycle 25 (like Solar Cycle 24 before it) will be one of the weakest since record-keeping began in 1755.“

15.09.2020 - 18:01 [ Europäische Weltraumagentur / European Space Agency - ESA.int ]

Secrets for Solar Orbiter to solve

(04.09.2020)

The Sun’s magnetic field is responsible for all the solar activity we see; it drives the 11-year ebb and flow in the number of sunspots, and dominates the behaviour of the solar atmosphere. Furthermore, this magnetic field surrounds the entire solar system, creating a giant bubble known as the heliosphere that is filled with electrified gas known as plasma. Disturbances in this plasma can affect the planets, creating aurorae and interfering with the behaviour of technology. Yet the details of the magnetic field’s initial generation inside the Sun are not yet understood.

15.09.2020 - 13:26 [ EOS.org ]

The Thermosphere Responds to a Weaker Than Normal Solar Cycle

(05.04.2019)

The cooling near solar minimum is natural and specific to the thermosphere. The cooling thermosphere does not affect the troposphere, the layer of the atmosphere closest to Earth’s surface where people live. The temperatures we experience on the ground do not get colder because of this solar cycle. NASA and other climate researchers continue to see a warming trend in the troposphere. These two effects are ongoing but unrelated.

Nitric oxide and carbon dioxide play important roles in cooling the thermosphere.

09.08.2020 - 08:07 [ journals.plos.org ]

The Earth’s magnetic field in Jerusalem during the Babylonian destruction: A unique reference for field behavior and an anchor for archaeomagnetic dating

Archaeomagnetism, the application of paleomagnetic methods to archaeological materials, is interdisciplinary not only in its methods but also in its impact. Well-dated archaeological materials are a critical data source for geomagnetic secular variation models [1–6], which are used to explore the dynamic structure of Earth’s core [7, 8], the rates of cosmogenic isotope production in the atmosphere [9–11] and the possible effect of geomagnetism on climate [11–13]. Precise documentation of the ancient field also helps contextualize geomagnetic observations from the modern era, such as the evolution of the South Atlantic Anomaly [14, 15] and the ongoing decline in the field’s intensity [16–18].

09.08.2020 - 08:05 [ Haaretz ]

Ruins of Ancient Jerusalem Help Unravel Enigmas of Earth’s Magnetic Field

Albert Einstein once called the behavior of the magnetic field one of the great mysteries of physics, but understanding and possibly predicting its changes has taken on a new urgency for scientists. The field has lost around 10 percent of its strength since measurements began less than 200 years ago, leading some researchers to question whether we are on the way to a flip in polarity, which would be preceded by a loss of our precious shield against cosmic radiation.