The northern lights are caused by the solar wind, a stream of charged particles from the sun that interacts with Earth’s magnetic field. As charged particles strike Earth’s magnetic field, they accelerate down its magnetic field lines at the north and south poles, exciting particles in the atmosphere to create ovals of green and red.
Archiv: Sonnenaktivität / Sonnenwind / solar activity / solar wind
NASA’s IMAP Begins Primary Science Mission
(February 2, 2026)
NASA’s IMAP (Interstellar Mapping and Acceleration Probe) began its two-year primary science mission on Feb. 1 to explore and map the boundaries of our heliosphere — the protective bubble created by the solar wind that encapsulates our solar system.
The mission, which launched on Sept. 24, 2025, relies on 10 scientific instruments to chart a comprehensive picture of what’s roiling in space, from high-energy particles originating at the Sun, to magnetic fields in interplanetary space, to dust left from exploded stars in interstellar space.
NASA begins mission to map the boundaries of our heliosphere
(February 3, 2026)
A NASA probe has started its mission to map the heliosphere, which is a huge protective bubble around the solar system that was created by the sun, the space agency announced on Monday.
The space agency‘s Interstellar Mapping and Acceleration Probe, or IMAP, is expected to continue its mission for two years, using scientific instruments to chart the boundaries of the heliosphere and what‘s going on inside of it.
The probe is focusing on high-energy particles bursting from the surface of the sun, the magnetic fields that form in the spaces between planets, and the dust left behind by collapsed stars farther out in the galaxy.
Early riser! The Sun is already starting its next solar cycle
(July 19, 2024)
The current solar cycle, named Cycle 25 because it is the 25th since 1755 when extensive recording of solar sunspot activity began, started in 2019.
It is not expected to end for another six years but the first signs that the next solar cycle is beginning have been spotted by researchers from the University of Birmingham and presented at the Royal Astronomical Society‘s National Astronomy Meeting in Hull.
Interactive: Why auroras are surging during one of the weakest solar cycles in 126 years
(February 12, 2026)
Scientists call the current cycle Solar Cycle 25, the 25th numbered cycle since recordkeeping began in the 1700s. Even though it may feel like the northern lights have been more common in recent years, Solar Cycle 25 ranks among the lowest of the past 126 years.
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Earth’s magnetic field has been slowly weakening for more than a century, which means our natural shield isn’t quite as strong as it used to be. That doesn’t create solar storms, but it can change how much of that energy actually makes it through when a strong one hits.
The Shrinking of the Heliosphere Due to Reduced Solar Wind
(December 2009)
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.
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1.4 Prediction of the State of solar Activity During The Next Few Decades
Weak solar cycles occur at the bottom of Wolf-Gleissberg cycles. They tend to occur in series of 3-4 cycles. A single weak cycle also occurs in between the two maximums of Wolf-Gleissberg cycle. Since the last weak solar cycles occurred around 1900 while the previous ones occurred around 1800 then the newly started cycle 24 should be a weak solar cycle. However, owing to the 200-years de Verie cycle of the sun, it is more likely that the status of the coming solar activity would be something like those weak cycles around 1800 as shown in Fig 1. Svalgaard (2005) also predicted that cycle 24 would be the lowest so far in the past 100 years with the maximum sunspot number around 75.
Surprise: Solar System „Force Field“ Shrinks Fast
(October 1, 2010)
For starters, it‘s been assumed that the heliosphere‘s expansion and contraction follows the sun‘s roughly 11-year activity cycle, during which the flow rate of charged particles, or solar wind, fluctuates.
But when scientists compared IBEX maps of the heliosphere taken just six months apart, the researchers found that it had shrunk to a much greater extent than expected.
Sun‘s protective ‚bubble‘ is shrinking
(October 18, 2008)
The scientists hope the IBEX mission will allow them to gain a better understanding of what happens at this boundary and help them predict what protection it will offer in the future.
Without the heliosphere the harmful intergalactic cosmic radiation would make life on Earth almost impossible by destroying DNA and making the climate uninhabitable.
Measurements made by the Ulysses deep space probe, which was launched in 1990 to orbit the sun, have shown that the pressure created inside the heliosphere by the solar wind has been decreasing.
Energy coupling between the solar wind and the magnetosphere
(June 1981)
This paper describes in detail how we are led to the first approximation expression for the solar wind-magnetosphere energy coupling function ɛ, which correlates well with the total energy consumption rate U T of the magnetosphere. It is shown that ɛ is the primary factor which controls the time development of magnetospheric substorms and storms. The finding of this particular expression ɛ indicates how the solar wind couples its energy to the magnetosphere; the solar wind and the magnetosphere constitute a dynamo. In fact, the power P generated by the dynamo can be identified as ɛ by using a dimensional analysis. Furthermore, the finding of ɛ indicates that the magnetosphere is closer to a directly driven system than to an unloading system which stores the generated energy before converting it to substorm and storm energies.
Physics Professor Gerard Fasel and Seaver Students Present Solar-Terrestrial Interactions at the American Geophysical Union Conference
(January 13, 2026)
Coining the term “near-Earth astrophysics,” Fasel has devoted much of his career to investigating solar-terrestrial interactions between the Sun and Earth, using the aurora borealis to obtain clues regarding the coupling mechanisms between the solar wind and the Earth’s terrestrial magnetic field.
“Stars have winds,” says Fasel. “And this includes our Sun. While solar wind is a relatively continuous stream of particles that interact with the Earth’s magnetic field, the Sun can also produce powerful solar storms. These storms expel billions of charged particles [plasma] coupled to magnetic fields, called coronal mass ejections, which bang up into the Earth’s magnetic field.”
The Earth’s magnetic field lines, Fasel explains, “act like wires” on which these particles travel down into the Earth’s upper atmosphere, specifically the ionosphere. The aurora is an end result of this interaction, where high-energy electrons collide with oxygen to produce green light, while those of lower energy produce a raspberry-red color.
Watch: Auroras Light Up Skies Worldwide
November 13, 2025
People across the United States weren’t the only ones treated to a spectacular celestial show. This week’s intense geomagnetic storm illuminated the night sky around the world. Check out some of the most stunning displays from Europe to Mongolia to Australia.
Early riser! The Sun is already starting its next solar cycle
(July 19, 2024)
The current solar cycle, named Cycle 25 because it is the 25th since 1755 when extensive recording of solar sunspot activity began, started in 2019.
It is not expected to end for another six years but the first signs that the next solar cycle is beginning have been spotted by researchers from the University of Birmingham and presented at the Royal Astronomical Society‘s National Astronomy Meeting in Hull.
The next solar cycle – Solar Cycle 26 – is already beginning
(July 23, 2024)
Solar max affects activity on the sun’s surface. Sunspots, flares and coronal mass ejections are all more rampant at solar maximum. This leads to a surge in electromagnetic energy hurtling toward Earth, making auroras visible more often and at lower altitudes.
The current solar cycle – Cycle 25 – started in 2019. It has the name Cycle 25 because it’s the 25th since 1755, when extensive recording of solar sunspot activity began.
It is not expected to end for another six years, but researchers have spotted the first signs that the next solar cycle is beginning. Researchers from the University of Birmingham presented their findings at the Royal Astronomical Society’s National Astronomy Meeting in Hull on July 18, 2024.
Detailed understanding of reduced geoeffectiveness of solar cycle 24 in association with geomagnetic storms
(May 2025)
Solar Cycle 24, the weakest in over a century, exhibited significant deviations from previous cycles, beginning with a prolonged minimum, weak polar fields, and asynchronous polar field reversal, leading to hemispheric asymmetry. Sunspot activity declined by approximately 30% compared to Cycle 23, while the overall occurrence rate of coronal mass ejections (CMEs) decreased, although some studies suggest that the rate of halo CMEs relative to total CMEs may have remained relatively stable. This study investigates the impact of weaker solar activity on geomagnetic storm dynamics by analyzing CME properties, solar wind conditions, and their influence on magnetospheric energy transfer. Key findings indicate that a lower heliospheric pressure in Cycle 24 caused CMEs to expand more than in Cycle 23, altering energy transfer to Earth‘s magnetosphere.
The Weakest Solar Cycle in 100 Years
(July 24, 2013)
The Sun is acting weird. It typically puts on a pageant of magnetic activity every 11 years for aurora watchers and sungazers alike, but this time it overslept. When it finally woke up (a year late), it gave the weakest performance in 100 years.
What’s even weirder is that scientists, who aren’t usually shy about tossing hypotheses about, are at a loss for a good explanation.
The Shrinking of the Heliosphere Due to Reduced Solar Wind
(December 2009)
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.
(…)
1.4 Prediction of the State of solar Activity During The Next Few Decades
Weak solar cycles occur at the bottom of Wolf-Gleissberg cycles. They tend to occur in series of 3-4 cycles. A single weak cycle also occurs in between the two maximums of Wolf-Gleissberg cycle. Since the last weak solar cycles occurred around 1900 while the previous ones occurred around 1800 then the newly started cycle 24 should be a weak solar cycle. However, owing to the 200-years de Verie cycle of the sun, it is more likely that the status of the coming solar activity would be something like those weak cycles around 1800 as shown in Fig 1. Svalgaard (2005) also predicted that cycle 24 would be the lowest so far in the past 100 years with the maximum sunspot number around 75.
11 Years Charting Edge of Solar System
Jun 11, 2020
Far, far beyond the orbits of the planets lie the hazy outlines of the magnetic bubble in space that we call home.
This is the heliosphere, the vast bubble that is generated by the Sun’s magnetic field and envelops all the planets. The borders of this cosmic bubble are not fixed. In response to the Sun’s gasps and sighs, they shrink and stretch over the years.
Now, for the first time, scientists have used an entire solar cycle of data from NASA’s IBEX spacecraft to study how the heliosphere changes over time. Solar cycles last roughly 11 years, as the Sun swings from seasons of high to low activity, and back to high again. With IBEX’s long record, scientists were eager to examine how the Sun’s mood swings play out at the edge of the heliosphere. The results show the shifting outer heliosphere in great detail, deftly sketch the heliosphere’s shape — a matter of debate in recent years, and hint at processes behind one of its most puzzling features. These findings, along with a newly fine-tuned data set, are published in The Astrophysical Journal Supplements on June 10, 2020.
NASA confirms Voyager spacecraft has encountered a “wall of fire” at the edge of the Solar System
(November 6, 2025)
According to NASA, Voyager 1 has now encountered what researchers describe as a “wall of fire,” a zone where temperatures reach between 30,000 and 50,000 kelvin — roughly 30,000 degrees Celsius. The finding was made as part of ongoing efforts to understand the boundary separating our Solar System from interstellar space.
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“An observation made by Voyager 2 confirms a surprising result from Voyager 1: the magnetic field in the region just beyond the heliopause is parallel to the magnetic field inside the heliosphere,” NASA noted. With data from both spacecraft, scientists can now confirm that this alignment is not a coincidence but a defining characteristic of the boundary region.
The Earth’s Magnetic Field Is Rapidly Weakening—And Scientists Are Tracking Every Change
(July 29, 2025)
1. The Magnetic Field’s Essential Role
Earth’s magnetic field acts as a protective barrier against the relentless bombardment of solar wind and cosmic rays. Without this shield, high-energy particles from the Sun would strip away our atmosphere, exposing living organisms to dangerous radiation.
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12. Atmospheric and Climate Connections
Researchers are investigating whether a weaker magnetic field could alter Earth’s atmosphere or climate.
Aurora Borealis Displays STUNNED Americans Across the Country
The northern lights lit up the night sky across America on Tuesday, dazzling stargazers from New Hampshire to the heartland with eerie green and orange streaks of cosmic fire.
The U.S. saw vivid northern lights as far south as Florida — and more could be coming
The Aurora Borealis was spotted in a large swath of states, including Idaho, Iowa, Missouri, New Mexico, New York, Oklahoma, South Dakota, Tennessee, Texas and Washington state. Northern lights were visible as far south as parts of Florida and Alabama, a relatively rare occurrence that highlights the severity of this week‘s storms.
Rare solar storm lights up Northern California skies
A surge in solar activity fueled the vibrant display as the sun reached the peak of its 11-year solar cycle, a period marked by a sharp increase in sunspots and geomagnetic storms.
Around 2019–2020, the sun was at its quietest point; however, with more frequent bursts of solar wind erupting from those sunspots, Earth is now experiencing more substantial and more frequent auroral events.
Farbenfrohes Himmelsphänomen: Polarlichter über Baden-Württemberg
Etwas Besonderes sind die Polarlichter in Süddeutschland auch, weil sie kein häufiges Phänomen sind. Skandinavien ist für die Sonnenstürme bekannt. „Tatsächlich ist Polarlicht in Süddeutschland schon sehr, sehr selten“, sagt Liefke.
The Voyagers Are Still Exploring 40 Years Later
(Oct. 12, 2024)
From their unique vantage points – Voyager 1 in the northern hemisphere and Voyager 2 in the southern hemisphere – the spacecraft have already detected differences and asymmetries in the solar wind termination shock, where the wind abruptly slows as it approaches the heliopause. For example, Voyager 2 crossed the termination shock at a distance of about 83.7 AU in the southern hemisphere. (One AU, or astronomical unit, is equal to 150 (million) kilometers (93 million miles), the distance between Earth and the Sun.) That’s about 10 AU closer to the Sun than where Voyager 1 crossed the shock in the north. As shown in this diagram, Voyager 1 traveled through the compressed “nose” of the termination shock and Voyager 2 is expected to travel through the flank of the termination shock.
Our planet is in a space balloon, literally
(June 16, 2024)
But only two human-made objects have crossed the boundary of the solar system and entered interstellar space.
In 1977, NASA launched Voyager 1 and Voyager 2, equipped with tools to measure the magnetic fields and the particles it is directly passing through. After traveling for over three decades in space, they finally exited the outer layer of the heliosphere—heliopause in 2012 and 2018 respectively. They discovered that cosmic rays are about three times more intense outside the heliopause than deep inside the heliosphere.
PUNCH – Polarimeter to Unify the Corona and Heliosphere
Key Questions
The PUNCH mission will use four suitcase-sized satellites to observe the Sun and its environment. Working together, the four PUNCH satellites will create a combined field of view and map the region where the Sun’s corona (or outer atmosphere) transitions to the solar wind (the constant outflow of material from the Sun).
The PUNCH mission will answer questions about:
How the Sun’s atmosphere transitions to the solar wind.
How structures in the solar wind are created.
How these processes affect the solar system.
NASA will soon launch PUNCH to study how the Sun influences the space around us
On March 2, a SpaceX Falcon 9 rocket is scheduled to launch the Polarimeter to Unify the Corona and Heliosphere (PUNCH) mission into low Earth orbit. From this location, its four satellites will have nearly constant views of the Sun to help researchers answer questions about how activity near our star propagates through the inner solar system, influencing the space weather we experience here on Earth.