Blog

Our Sun, despite appearing warm and calm from Earth, is a giant ball of fiery gas that constantly churns and releases incredible bursts of energy. Sometimes, these bursts manifest as spectacular solar flares or massive expulsions of plasma known as coronal mass ejections, which can impact Earth’s technology, ranging from satellites to power grids. But even on a smaller scale, the Sun is incredibly dynamic, with constant activity that helps us understand the fundamental processes driving these larger, more impactful events. One such fascinating phenomenon is the chromospheric fan-shaped jet, often described as light walls or peacock jets due to their appearance. These jets are like miniature, recurrent fireworks erupting from the Sun’s lower atmosphere, the chromosphere. Understanding them gives us a clearer picture of the Sun’s secrets.
Recently, a team of researchers from the Indian Institute of Astrophysics, Bengaluru, University of Oslo, Norway,  NASA Marshall Space Flight Center, USA, University of Alabama in Huntsville, USA, and the Big Bear Solar Observatory, USA,  studied the mechanics behind these intriguing fan-shaped jets. They wanted to understand what makes these jets appear repeatedly, sometimes lasting for over an hour, and how they are powered. 

Previous studies had often focused on similar jets originating from light bridges, which are bright structures found within the dark centres of sunspots. However, this new research focused on jets that appear in the intergranular lanes – the spaces between the granular patterns on the Sun’s surface, specifically between sunspots that have the same magnetic polarity. This distinction is important because it shows that similar energetic processes can occur in different magnetic environments on the Sun.

To unravel this mystery, the researchers used a combination of telescopes. They gathered high-resolution images from the Goode Solar Telescope (GST) at the Big Bear Solar Observatory, which provided incredibly detailed views of the jets in a specific wavelength of light. They combined this with data from instruments aboard NASA’s Solar Dynamics Observatory (SDO): the Atmospheric Imaging Assembly (AIA), which captures images of the Sun in various ultraviolet wavelengths, and the Helioseismic and Magnetic Imager (HMI), which maps the Sun’s magnetic fields. By looking at the jets in different wavelengths of light and observing the magnetic field changes, they could piece together the complete picture.

They discovered a dramatic interplay of magnetic forces. The HMI magnetic field maps revealed a crucial event happening at the base of these jets: magnetic flux cancellation. This is essentially when magnetic field lines of opposite polarities meet and effectively cancel each other out. The researchers observed a gradual decrease in these opposite-polarity magnetic fields right where the jets were forming. As this cancellation occurred, the jets became more intense, and they eventually stopped when the minority magnetic field disappeared entirely. This strongly suggests that magnetic reconnection, a process where tangled magnetic field lines break and reconnect, releasing immense energy, is the primary driver.

Further analysis, using computer models to extrapolate the magnetic field into three dimensions, showed a complex magnetic structure at the jet’s base. They found what’s called a 3D magnetic null point at a height of about 1.25 million meters (or 1250 kilometres) above the Sun’s surface. This is a hypothetical point where the magnetic field strength drops to zero, and around it, the magnetic field lines form a specific fan-spine shape. This kind of topology is known to be very favorable for magnetic reconnection. 

The researchers propose that these observations align perfectly with a model called the minifilament eruption model, which was previously used to explain larger jets in the Sun’s corona (the outermost atmosphere). In this model, a small, twisted bundle of magnetic field lines, like a tiny magnetic rope, becomes unstable and erupts. This eruption triggers two types of magnetic reconnection: internal reconnection at the base, which creates a bright point, and external reconnection higher up, which then forms the fan-shaped jet, propelling plasma outwards. This study provides strong evidence that this minifilament eruption mechanism, driven by magnetic flux cancellation, is responsible for these recurrent chromospheric fan-shaped jets.

The work demonstrates that the minifilament eruption model, previously applied to coronal jets, also explains these smaller, recurrent chromospheric jets. Crucially, it highlights that the magnetic conditions necessary for these jets, driven by flux cancellation, can exist not only in sunspot light bridges but also in the intergranular lanes between sunspots. While the study provides compelling evidence, the researchers acknowledge that such observations are rare, which limits the number of events that can be studied in detail.

Understanding these recurrent fan-shaped jets, even if they seem small compared to massive solar flares, is vital for society. The Sun’s activity, from the smallest jets to the largest eruptions, is all interconnected. By studying these fundamental processes, scientists can build more accurate models of the Sun’s magnetic behaviour. This, in turn, helps us better predict space weather events that can disrupt our modern technological world. Every piece of the solar puzzle, including these beautiful fan-shaped jets, brings us closer to a future where we can better prepare for and mitigate the effects of the Sun’s powerful temperament.

This article was written with the help of generative AI and edited by an editor at Research Matters.

This photo taken on July 9, 2025 shows a press conference held by the Chinese Academy of Sciences (CAS) in Beijing, capital of China. A series of research findings by Chinese scientists on the samples collected by the Chang’e-6 mission from the moon’s far side have unveiled the volcanic activity, ancient magnetic field, water content and geochemical characteristics of the moon mantle, shedding the first light on the evolutionary history of its dark side. Four studies by the research teams from the Institute of Geology and Geophysics (IGG), the National Astronomical Observatories, both under the Chinese Academy of Sciences (CAS), Nanjing University, and other institutions were published in the latest issue of Nature. As the moon’s revolution cycle is the same as its rotation cycle, the same side always faces Earth. The other face, most of which cannot be seen from Earth, is called the far, or dark, side of the moon. This term doesn’t refer to visible darkness, but rather the mystery shrouding the moon’s largely unexplored terrain. (Xinhua/Jin Liwang)

BEIJING, July 9 (Xinhua) — A series of research findings by Chinese scientists on the samples collected by the Chang’e-6 mission from the moon’s far side have unveiled the volcanic activity, ancient magnetic field, water content and geochemical characteristics of the moon mantle, shedding the first light on the evolutionary history of its dark side.

Four studies by the research teams from the Institute of Geology and Geophysics (IGG), the National Astronomical Observatories, both under the Chinese Academy of Sciences (CAS), Nanjing University, and other institutions were published in the latest issue of Nature.

As the moon’s revolution cycle is the same as its rotation cycle, the same side always faces Earth. The other face, most of which cannot be seen from Earth, is called the far, or dark, side of the moon. This term doesn’t refer to visible darkness, but rather the mystery shrouding the moon’s largely unexplored terrain.

The moon’s near and far sides exhibit significant differences in morphology, composition, crustal thickness and magmatic activities. However, the mechanisms behind these disparities remain unresolved, representing a key issue in lunar science. Previously, scientific understanding of the far side relied primarily on remote sensing studies, scientists say.

In 2024, Chang’e-6 made history by bringing 1,935.3 grams of lunar far-side samples back to Earth. These samples were collected from the South Pole-Aitken (SPA) Basin, the largest, deepest and oldest basin on the moon, which provided a rare opportunity to clarify the compositional differences between the near and far sides and to unravel the long-standing mystery of their asymmetry.

“The SPA Basin is one of the moon’s three major tectonic units, measuring approximately 2,500 kilometers in diameter. The energy from the impact that formed this crater is estimated to be 1 trillion times greater than that of an atomic bomb explosion. Yet, the exact influence of such a massive collision on the moon’s evolution has remained an unsolved mystery,” Wu Fuyuan, an academician of CAS and a leading researcher with the IGG, said at a CAS press conference on Wednesday.

The four papers published in Nature systematically reveal, for the first time, the effects of this colossal impact, which is the core highlight of these findings, said Wu.

Over the past year, Chinese scientists have achieved multiple pioneering breakthroughs through the study of the Chang’e-6 samples.

They found the evidence of volcanic activity on the moon’s far side approximately 4.2 billion and 2.8 billion years ago, indicating such activity had persisted for at least 1.4 billion years.

For the first time, scientists obtained the ancient magnetic field information from the far side of the moon, revealing a possible rebound in the moon’s magnetic field intensity around 2.8 billion years ago. This discovery indicates the presence of fluctuations in the driven power of the lunar dynamo.

Scientists have found that the water content in the lunar far-side mantle is significantly lower than that of the near side, indicating a significant difference in water distribution between the two hemispheres.

“We found that the mantle source of basalt from the SPA basin is extremely depleted in incompatible elements, which are commonly used to reveal the geological processes that rocks have undergone,” said Yang Wei, a researcher with IGG.

This depletion could mean either the original lunar mantle was very low in the incompatible elements, or the massive impact event melted the rocks and carried these elements away. This discovery underscores the profound influence of large impacts on the evolution of the moon’s deep interior, Yang said.

“The new discovery marks humanity’s first direct access to key evidence of the deep interior material properties on the far side of the moon. It provides us with unique information to understand how the moon’s early interior became layered, cooled and evolved, representing a crucial step toward unraveling the mystery behind the dramatic differences between the lunar near and far sides,” said Li Chunlai, a researcher at the National Astronomical Observatories of CAS and deputy chief designer of the Chang’e-6 mission.

Additionally, Chinese scientists have made other discoveries. They unveiled the physical, mineralogical and geochemical characteristics of the Chang’e-6 lunar samples.

Meanwhile, Chinese scientists precisely determined for the first time that the SPA Basin formed 4.25 billion years ago, providing humanity with a more accurate anchor point for studying the history of large-scale impacts in the early solar system.

Mahesh Anand, a professor at the Open University in the UK, said, “We have had samples from the moon for over 50 years, samples collected by the Apollo and Luna missions. And we have many lunar meteorites.”

“But there are lots of new findings that are coming out based on the work that has been done on Chang’e-6 samples that are actually turning many of the well established hypotheses and theories in the field of lunar science upside down, necessitating reexamination of many of those theories,” Anand said.

He Hongping, vice president of CAS, said that upon receiving the Chang’e-6 lunar samples, CAS has placed high priority on related research efforts, and has yielded a series of high-level research achievements.

Guan Feng, director of the Lunar Exploration and Space Engineering Center of the China National Space Administration, expressed the hope that the comprehensive development of space science, space technology and space applications will be further promoted, urging more scientists to make use of the extraterrestrial samples and scientific data obtained from China’s lunar and deep space exploration missions to achieve more results and make more discoveries.

Previously, Chinese scientists analyzed the samples collected by the Chang’e-5 mission from the moon’s near side, and found evidence of young volcanic activity dating back just 2 billion years, extending the moon’s volcanic timeline by 1 billion years. This discovery was hailed by international peers as changing humanity’s understanding of lunar evolution.

The success of China’s lunar exploration program is a prime example of the deep integration between science and engineering, said Li of the National Astronomical Observatories.

Ouyang Ziyuan (C), an academician with the Chinese Academy of Sciences (CAS), speaks during a CAS press conference in Beijing, capital of China, on July 9, 2025. A series of research findings by Chinese scientists on the samples collected by the Chang’e-6 mission from the moon’s far side have unveiled the volcanic activity, ancient magnetic field, water content and geochemical characteristics of the moon mantle, shedding the first light on the evolutionary history of its dark side.Four studies by the research teams from the Institute of Geology and Geophysics (IGG), the National Astronomical Observatories, both under the Chinese Academy of Sciences (CAS), Nanjing University, and other institutions were published in the latest issue of Nature. As the moon’s revolution cycle is the same as its rotation cycle, the same side always faces Earth. The other face, most of which cannot be seen from Earth, is called the far, or dark, side of the moon. This term doesn’t refer to visible darkness, but rather the mystery shrouding the moon’s largely unexplored terrain. (Xinhua/Jin Liwang)

Hui Hejiu, professor of Nanjing University, speaks during a press conference held by the Chinese Academy of Sciences (CAS) in Beijing, capital of China, on July 9, 2025. A series of research findings by Chinese scientists on the samples collected by the Chang’e-6 mission from the moon’s far side have unveiled the volcanic activity, ancient magnetic field, water content and geochemical characteristics of the moon mantle, shedding the first light on the evolutionary history of its dark side. Four studies by the research teams from the Institute of Geology and Geophysics (IGG), the National Astronomical Observatories, both under the Chinese Academy of Sciences (CAS), Nanjing University, and other institutions were published in the latest issue of Nature. As the moon’s revolution cycle is the same as its rotation cycle, the same side always faces Earth. The other face, most of which cannot be seen from Earth, is called the far, or dark, side of the moon. This term doesn’t refer to visible darkness, but rather the mystery shrouding the moon’s largely unexplored terrain. (Xinhua/Jin Liwang)

This photo taken on July 9, 2025 shows a press conference held by the Chinese Academy of Sciences (CAS) in Beijing, capital of China. A series of research findings by Chinese scientists on the samples collected by the Chang’e-6 mission from the moon’s far side have unveiled the volcanic activity, ancient magnetic field, water content and geochemical characteristics of the moon mantle, shedding the first light on the evolutionary history of its dark side. Four studies by the research teams from the Institute of Geology and Geophysics (IGG), the National Astronomical Observatories, both under the Chinese Academy of Sciences (CAS), Nanjing University, and other institutions were published in the latest issue of Nature. As the moon’s revolution cycle is the same as its rotation cycle, the same side always faces Earth. The other face, most of which cannot be seen from Earth, is called the far, or dark, side of the moon. This term doesn’t refer to visible darkness, but rather the mystery shrouding the moon’s largely unexplored terrain. (Xinhua/Jin Liwang)

Ouyang Ziyuan (2nd R), an academician with the Chinese Academy of Sciences (CAS), speaks during a CAS press conference in Beijing, capital of China, on July 9, 2025. A series of research findings by Chinese scientists on the samples collected by the Chang’e-6 mission from the moon’s far side have unveiled the volcanic activity, ancient magnetic field, water content and geochemical characteristics of the moon mantle, shedding the first light on the evolutionary history of its dark side. Four studies by the research teams from the Institute of Geology and Geophysics (IGG), the National Astronomical Observatories, both under the Chinese Academy of Sciences (CAS), Nanjing University, and other institutions were published in the latest issue of Nature. As the moon’s revolution cycle is the same as its rotation cycle, the same side always faces Earth. The other face, most of which cannot be seen from Earth, is called the far, or dark, side of the moon. This term doesn’t refer to visible darkness, but rather the mystery shrouding the moon’s largely unexplored terrain. (Xinhua/Jin Liwang)

Wu Fuyuan, an academician of the Chinese Academy of Sciences (CAS) and a leading researcher with the Institute of Geology and Geophysics (IGG), speaks during a CAS press conference in Beijing, capital of China, on July 9, 2025. A series of research findings by Chinese scientists on the samples collected by the Chang’e-6 mission from the moon’s far side have unveiled the volcanic activity, ancient magnetic field, water content and geochemical characteristics of the moon mantle, shedding the first light on the evolutionary history of its dark side. Four studies by the research teams from the Institute of Geology and Geophysics (IGG), the National Astronomical Observatories, both under the Chinese Academy of Sciences (CAS), Nanjing University, and other institutions were published in the latest issue of Nature. As the moon’s revolution cycle is the same as its rotation cycle, the same side always faces Earth. The other face, most of which cannot be seen from Earth, is called the far, or dark, side of the moon. This term doesn’t refer to visible darkness, but rather the mystery shrouding the moon’s largely unexplored terrain. (Xinhua/Jin Liwang)

Li Chunlai, a researcher with the National Astronomical Observatories of the Chinese Academy of Sciences (CAS) and deputy chief designer of the Chang’e-6 mission, speaks during a CAS press conference in Beijing, capital of China, on July 9, 2025. A series of research findings by Chinese scientists on the samples collected by the Chang’e-6 mission from the moon’s far side have unveiled the volcanic activity, ancient magnetic field, water content and geochemical characteristics of the moon mantle, shedding the first light on the evolutionary history of its dark side. Four studies by the research teams from the Institute of Geology and Geophysics (IGG), the National Astronomical Observatories, both under the Chinese Academy of Sciences (CAS), Nanjing University, and other institutions were published in the latest issue of Nature. As the moon’s revolution cycle is the same as its rotation cycle, the same side always faces Earth. The other face, most of which cannot be seen from Earth, is called the far, or dark, side of the moon. This term doesn’t refer to visible darkness, but rather the mystery shrouding the moon’s largely unexplored terrain. (Xinhua/Jin Liwang)

This image created by Chinese researchers shows the moon’s far side. A series of research findings by Chinese scientists on the samples collected by the Chang’e-6 mission from the moon’s far side have unveiled the volcanic activity, ancient magnetic field, water content and geochemical characteristics of the moon mantle, shedding the first light on the evolutionary history of its dark side. Four studies by the research teams from the Institute of Geology and Geophysics (IGG), the National Astronomical Observatories, both under the Chinese Academy of Sciences (CAS), Nanjing University, and other institutions were published in the latest issue of Nature. As the moon’s revolution cycle is the same as its rotation cycle, the same side always faces Earth. The other face, most of which cannot be seen from Earth, is called the far, or dark, side of the moon. This term doesn’t refer to visible darkness, but rather the mystery shrouding the moon’s largely unexplored terrain. (CAS/Handout via Xinhua)

(Web editor: Zhang Kaiwei, Liang Jun)