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We already knew that interstellar comet 3I/ATLAS was different from the other two interstellar objects known to have traversed the Solar System, but a slew of new observations suggest it may be even weirder than the weirder that it was.

NASA and ESA instruments Hubble, SPHEREx, JWST, and TESS have all captured the object as it makes its way towards the Sun. The results show that not only was 3I/ATLAS actively outgassing long before we spotted it, but its atmosphere (or coma) has a higher proportion of carbon dioxide than scientists usually see in comets, interstellar or otherwise.

This could tell us something about the environment in which 3I/ATLAS formed, the space conditions through which it has traveled, or even the internal composition of the comet.

Related: Fuzzy, Large, And Very Old: Everything We Know About Interstellar Comet 3I/ATLAS

The comet first came to our attention on 1 July 2025, and astronomers have been avidly goggling at it ever since – not least because they have a very limited window in which to do so. Its closest approach to the Sun, or perihelion, will take place on October 29; but, because it’s on the other side of the Sun from Earth, it will be hidden behind the star’s blazing glow by this time.

This means that the best time for observing the comet before perihelion is rapidly slipping by, so scientists are making the best of it, turning some of our most powerful instruments to the task – or, in the case of TESS, scouring pre-discovery data for glimpses of the object.

It’s for this reason that we now know the first known glimpse of 3I/ATLAS took place back in May, nearly two full months before the official discovery. The comet was moving a lot faster than the targets TESS is designed to study, so researchers had to use some image-stacking techniques to reveal it.

This is where it gets interesting. The TESS data suggest that the comet was already active at that time, at a distance of around 6 astronomical units (AU) from the Sun – out past the orbit of Jupiter. That’s a much greater distance than expected: most comets begin showing activity no closer than 5 AU from the Sun.

When we call a comet active, it means that it has warmed up enough for the ices on and just under its surface to sublime – transition directly from a frozen to a gaseous state. This produces a coma and, eventually, if the comet comes close enough to the Sun to be affected by radiation pressure, cometary tails.

In their preprint paper, the researchers who made the TESS discovery posit that the comet’s early awakening may have had something to do with its composition. Some ices sublime more readily than others – and carbon dioxide is one of those ices.

This was confirmed by two separate, independent measurements using two different instruments. In mid-August 2025, NASA’s brand-spanking-new space telescope SPHEREx took multi-spectral observations of the comet at distances between 3.3 and 3.1 AU from the Sun, clearly resolving a coma rich in carbon dioxide, as well as water.

No tails or jets were observed at this time, and the coma was measured out to a radius of 23 kilometers, suggesting that production rates were pretty high. (The comet itself, according to Hubble measurements, has a radius of about 2.8 kilometers.)

This is supported by measurements from JWST, which observed the comet at a distance of 3.32 astronomical units from the Sun in early August. Its data suggests that carbon dioxide and water exist in the coma at a ratio of 8 to 1 – among the highest proportion of carbon dioxide ever seen in a comet.

There could be several reasons for this.

“Our observations are compatible with an intrinsically CO₂-rich nucleus, which may indicate that 3I/ATLAS contains ices exposed to higher levels of radiation than Solar System comets, or that it formed close to the CO₂ ice line in its parent protoplanetary disk,” the researchers explain in their preprint paper.

“A low coma H₂O gas abundance may also be implied, for example, due to inhibited heat penetration into the nucleus, which could suppress the H₂O sublimation rate relative to CO₂ and CO.”

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We’re not really going to know more without more information on the comet, for which we may have to wait. As you can see in the animation above, its trajectory is going to take it behind the Sun relative to Earth, but at perihelion it may be close enough to Mars for Mars orbiters to catch a glimpse.

After perihelion is when things will get even more exciting. At this time, the comet will make its closest approach to Earth as it continues to zoom right on out of the Solar System. In theory, Juno could intercept it when it whizzes past Jupiter in March next year.

This is such a fascinating object, we can’t wait to see what else our intrepid astronomers are able to find.

The Hubble, TESS, SPHEREx, and JWST findings, which have not yet been peer-reviewed, are all available in separate listings on the preprint server arXiv.

Weak magnetic fields once exposed humans to radiation. People adapted with shelter, clothing, and mineral protection.

Our first meeting was a bit awkward. One of us is an archaeologist who studies how past peoples interacted with their environments. Two of us are geophysicists who investigate interactions between solar activity and Earth’s magnetic field.

When we first got together, we wondered whether our unconventional project, linking space weather and human behavior, could actually bridge such a vast disciplinary divide. Now, two years on, we believe the payoffs – personal, professional and scientific – were well worth the initial discomfort.

Our collaboration, which culminated in a recent paper in the journal Science Advances, began with a single question: What happened to life on Earth when the planet’s magnetic field nearly collapsed roughly 41,000 years ago?

Weirdness when Earth’s magnetic shield falters

The event is known as the Laschamps Excursion, a short but intense geomagnetic disruption named after volcanic deposits in France where it was first discovered. Near the end of the Pleistocene epoch, Earth’s magnetic poles did not undergo a full reversal, as they typically do every few hundred thousand years. Instead, they shifted erratically across thousands of miles, while the strength of the magnetic field fell to less than 10% of its present level.

Under normal conditions, Earth’s magnetic field behaves like a stable dipole, similar to a bar magnet. During the Laschamps Excursion, however, it broke apart into several weaker poles scattered across the globe. This fragmentation weakened the magnetosphere, Earth’s natural shield that normally blocks much of the solar wind and harmful ultraviolet radiation from reaching the surface.

With the magnetosphere compromised, models suggest that a variety of near-Earth effects would have occurred. Auroras, which today are usually confined to the polar regions, likely appeared much closer to the equator, and the planet was exposed to significantly higher levels of solar radiation than we experience now.

The skies some 41,000 years ago may therefore have been both dazzling and dangerous. Recognizing this, we as geophysicists began to wonder how such conditions might have influenced human populations of the time.

From an archaeological perspective, the answer was clear: they were indeed affected.

Human responses to ancient space weather

For people living during this period, the auroras would likely have been the most visible and dramatic consequence, perhaps provoking awe, fear, ritual practices, or other responses that are difficult to trace. The archaeological record rarely preserves direct evidence of such emotional or cognitive reactions.

The physiological consequences of heightened ultraviolet exposure, however, are easier to assess. With the magnetic field weakened, more harmful radiation reached the surface, increasing the risks of sunburn, vision damage, birth defects, and other health concerns.

In response, people may have adopted practical measures: spending more time in caves, producing tailored clothing for better coverage, or applying mineral pigment “sunscreen” made of ochre to their skin. As we describe in our recent paper, the frequency of these behaviors indeed appears to have increased across parts of Europe, where effects of the Laschamps Excursion were pronounced and prolonged.

During this time, both Neanderthals and Homo sapiens inhabited Europe, though their ranges likely overlapped only in certain regions. Archaeological findings indicate that these populations responded differently to environmental pressures, with some relying more heavily on shelter or material culture as forms of protection.

It is important to emphasize that the research does not claim space weather alone drove these changes in behavior, nor that the Laschamps event was responsible for Neanderthal extinction—a common misinterpretation. Instead, it may have been one of several factors, an unseen but influential force shaping human adaptation and innovation.

Cross-discipline collaboration

Collaborating across such a disciplinary gap was, at first, daunting. But it turned out to be deeply rewarding.

Archaeologists are used to reconstructing now-invisible phenomena like climate. We can’t measure past temperatures or precipitation directly, but they’ve left traces for us to interpret if we know where and how to look.

But even archaeologists who’ve spent years studying the effects of climate on past behaviors and technologies may not have considered the effects of the geomagnetic field and space weather. These effects, too, are invisible, powerful and best understood through indirect evidence and modeling. Archaeologists can treat space weather as a vital component of Earth’s environmental history and future forecasting.

Likewise, geophysicists, who typically work with large datasets, models and simulations, may not always engage with some of the stakes of space weather. Archaeology adds a human dimension to the science. It reminds us that the effects of space weather don’t stop at the ionosphere. They can ripple down into the lived experiences of people on the ground, influencing how they adapt, create and survive.

The Laschamps Excursion wasn’t a fluke or a one-off. Similar disruptions of Earth’s magnetic field have happened before and will happen again. Understanding how ancient humans responded can provide insight into how future events might affect our world – and perhaps even help us prepare.

Our unconventional collaboration has shown us how much we can learn, how our perspective changes, when we cross disciplinary boundaries. Space may be vast, but it connects us all. And sometimes, building a bridge between Earth and space starts with the smallest things, such as ochre, or a coat, or even sunscreen.

Reference: “Wandering of the auroral oval 41,000 years ago” by Agnit Mukhopadhyay, Sanja Panovska, Raven Garvey, Michael W. Liemohn, Natalia Ganjushkina, Austin Brenner, Ilya Usoskin, Mikhail Balikhin and Daniel T. Welling, 16 April 2025, Science Advances.
DOI: 10.1126/sciadv.adq7275

Adapted from an article originally published in The Conversation.

Agnit Mukhopadhyay has received funding from NASA Science Mission Directorate and the University of Michigan Rackham Graduate School.

Raven Garvey and Sanja Panovska do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

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The body has an intricate system to defend against infections where each type of immune cell plays a distinct role. Now, a study led by researchers from the Penn State College of Medicine has uncovered a new function of the immune cells that are known for making antibodies. They determined that, in response to flu infection, a specialized set of B cells produce a key signaling molecule that the immune system needs to develop a robust, long-term response to fight off infections.

It’s a function that has not previously been seen in these types of cells. The finding highlights a potential target for improving immunizations, particularly the flu vaccine, and future therapies for conditions like cancer and autoimmune disease. The team published their study in PLOS Pathogens.

It’s paradigm-shifting. The pathway for producing the cytokine called interleukin-1 beta – a messenger that helps coordinate immune response – has almost exclusively been seen in the body’s front-line, innate immune cells. Yet here, we see it in B cells in a specialized area of the lymph node called the germinal center, which is part of the body’s adaptive immune response. We don’t expect them to do that.”

S. Rameeza Allie, assistant professor of microbiology and immunology at the Penn State College of Medicine and senior author on the paper

When a pathogen like the flu virus enters the body, it sets off a cascade of responses, the research team explained. First, the body’s front-line defense, called innate immunity, jumps into action to battle the pathogen and broadly suppress the infection. At the same time, the body gathers information about the pathogen and develops a targeted response using B cells and T cells, two types of white blood cells. This adaptive immunity, while slower to develop, is crucial for survival because it remembers pathogens and provides long-lasting protection. If the immune system encounters the same pathogen again, it mounts a faster, more robust response and protects against re-infection.

Germinal centers are key to developing good adaptive immunity, the researchers explained. These are areas that form in the lymph nodes in response to an infection or immunization and act as a training ground for B cells. Germinal center B cells, or GC B cells, multiply and undergo rapid changes to produce highly specific antibodies and memory B cells.

“The focus of our lab is understanding how we make this germinal center work better so that we can have these very protective memory B cells,” Allie said. “Studies have shown that if you can make the germinal centers persist longer, the production of memory B cells is really good.”

Allie explained that the interleukin-1 beta is necessary for a high-quality germinal center. Germinal centers need T follicular helper (TFH) cells in order to persist, and these TFH cells, in turn, need interleukin-1 beta to function. Without interleukin-1 beta, there are fewer TFH cells and germinal centers are smaller in size.

This study demonstrated that GC B cells produce interleukin-1 beta locally in the germinal center, and supplies it to TFH cells, a relationship that was previously unknown, the researchers said. The findings highlight the two-way relationship between these immune cells and how they work together to promote better quality germinal centers.

“We’ve known about B cells for a long time, and we know that their prominent function is to produce antibodies. But here, we show that they aren’t just antibody-producing cells. They are also helper cells for other immune cells and are essential for TFH cells to do their job and therefore the germinal center, too,” said Juliana Restrepo Munera, doctoral candidate in cell and biological systems at the Penn State College of Medicine and first author of the study.

The research team validated their data in a mouse model of influenza and in human B cells. They found that GC B cells produce interleukin-1 beta through a well-studied mechanism which uses a multi-protein complex called the NLRP3 inflammasome. When activated, this protein complex triggers the release of cytokines like interleukin-1 beta. Prior to this work, this inflammasome wasn’t widely linked to adaptive immunity. The researchers found that the inflammasome and interleukin-1 beta were expressed by GC B cells but not by other B cells. Without the inflammasome or interleukin-1 beta, TFH cells didn’t function effectively and the germinal centers weren’t well formed.

This finding could point to ways to enhance the response and prolong the activity in the germinal center by targeting the NLRP3 inflammasome pathway or GC B cell-derived interleukin-1 beta, Restrepo Munera explained. It could inform future flu vaccine strategies to provide better protection against viruses that constantly evolve. It could also lead to better ways to manage immune response in conditions like autoimmune disease and cancer.

“There’s so much translational potential because this is a cytokine that’s been studied and has been used in clinical settings,” Allie said.

The research team said they plan to continue this line of research to understand what’s required for the formation of optimal germinal centers and how to enhance their interaction between the GC B cells and TFH cells.

Funding from the Penn State College of Medicine supported this work.