On Aug. 18, 1868, a French astronomer named Pierre Jules César Janssen discovered helium while observing a total solar eclipse in India.
During the eclipse, Janssen was using a spectroscope to look at the spectrum of light emitted by the sun. This tool allows scientists to determine what elements they're looking at. While observing solar prominences during the eclipse, Janssen noticed a bright yellow line that didn't correspond to any elements that was not yet discovered on Earth.
In the months that followed, English astronomer Norman Lockyer independently observed the same spectral line and concluded that it came from a previously unknown element, which was named helium after Helios, the Greek god of the sun.
Thirteen years later, the Italian physicist Luigi Palmieri found the first evidence of helium on Earth, in the lava of Mount Vesuvius.
Totality during the total solar eclipse on April 8, 2024 (composite image). (Image credit: Space.com / Josh Dinner)
Why it mattered
The detection of helium during the 1868 eclipse was the first time spectroscopy revealed an element in an astronomical object that had not yet been discovered on Earth, and highlights why spectroscopy is one of astronomy’s most powerful tools.
Like every other element on the periodic table, helium has innumerable applications, including some that are especially important to space and spaceflight. Scientists eventually learned that helium is the second-most abundant element in the universe (after hydrogen). And the fusion of hydrogen into helium is the process that powers stars like our sun. Helium gas is commonly used to pressurize and purge rocket propellant systems, and liquid helium is often used to cool sensitive scientific instruments on spacecraft.
The periodic table of the elements. (Image credit: Humdan/Shutterstock)
The "Black Eye Galaxy" is captured in this new composite image from the Hubble Space Telescope and JWST. (Image credit: NASA, CSA, ESA, F. Belfiore (European Southern Observatory – Germany), J. Lee (Space Telescope Science Institute), A. Leroy (The Ohio State University), and D. Thilker (The Johns Hopkins University); Processing: Gladys Kober (NASA/Catholic University of America))
Sometimes, incredibly powerful space telescopes work together to accomplish amazing things. Recently, observations made by both the James Webb Space Telescope and Hubble were combined in a composite image that shows the incredible nature of the "Black Eye Galaxy," more formally known as Messier 64.
What is it?
The Black Eye Galaxy is a strange spiral galaxy located 17 million light-years from Earth, in the constellation Coma Berenices, a name that means "Berenice's Hair" in Latin.
Discovered in 1779, the Black Eye Galaxy is fairly isolated from other galaxies and is known for its hypnotizing "stare." This look is created by the galaxy's internal, swirling motion. However, unlike many other spiral galaxies, the gas in the outer reaches of this one rotates in the opposite direction to the gas and stars closer to its center, creating an especially unusual motion.
To capture this incredible composite view of the galaxy, astronomers combined near and mid-infrared wavelength observations made by JWST and ultraviolet, visible and near-infrared observations made by Hubble.
Why is it incredible?
As we look forward to observations from NASA's upcoming flagship space observer, the Nancy Grace Roman Space Telescope, this collaborative effort shows how such powerful instruments don't replace one another; rather, they bring different capabilities to the table and can complement each other.
And, while this new image is the result of a team effort of cutting edge-technology, the Black Eye Galaxy is also a favorite target for backyard astronomers because it can often be spotted in small telescopes.
The Hubble Space Telescope has discovered evidence that our galaxy experienced a significant collision and merger with a dwarf galaxy 11.8 billion years ago.
Mergers between galaxies are one of the main ways in which galaxies can grow. However, while we can witness mergers taking place in other galaxies, figuring out our Milky Way galaxy's history requires painstaking detective work. Even now, the story is only partly known.
"Our home is the Milky Way galaxy, but we do not know how our house was built," Davide Massari of the Astrophysics and Space Science Observatory of Bologna in Italy said in a statement. Massari is lead author of a paper describing the discovery of an ancient galactic merger. "In this paper we discover where the first significant batch of bricks came from: a dwarf galaxy that we call LKH."
LKH stands for Low-energy–Kraken–Heracles, which is an obtuse reference to three earlier research papers that tangled with the idea of mergers early in our galaxy's history.
In recent years, one other significant merger has come to light, which is a collision with a galaxy referred to as the Gaia–Sausage–Enceladus (GSE) galaxy about 10 billion years ago. The GSE had its own family of globular star clusters that became integrated with the Milky Way's own globular clusters during the collision.
Now, Massari's team have discovered a third population of globular clusters that do not seem to be native to the Milky Way, nor to have belonged to the GSE galaxy. Instead, they seem to have arrived 11.8 billion years ago, which is before the GSE merger.
"Thanks to the high resolution and depth of Hubble imaging, we could measure the age and the metal content of these clusters with unprecedented precision," said astronomer Chiara Zerbinati of the University of Bologna, who is a co-author on the paper. Metals are astronomer-speak for elements heavier than the hydrogen and helium that formed in the Big Bang, so they include the likes of oxygen and carbon as well as iron and aluminum.
"Coupled with measurements from [the European Space Agency mission] Gaia, this made it possible to distinguish a population of globular clusters that are different from the others," said Zerbinati. "These are the clusters that were born in LKH and they tell us when that galaxy was devoured by ours, and how massive it was."
Based on the number and mass of imported globular clusters, the team calculated that LKH had a total mass of 500 million times the mass of our sun. This is only slightly more massive than the Sagittarius Dwarf galaxy (approximately 400 million solar masses), which the Milky Way is currently cannibalizing and an order of magnitude less massive than the Small Magellanic Cloud. However, 11.8 billion years ago, which is just two billion years after the Big Bang, our Milky Way galaxy was much smaller and LKH would have contributed a sizable chunk of mass, in terms of stars, gas and dark matter, to the Milky Way.
The discovery of the merger adds an important new event to the Milky Way's history, one that would have undoubtedly influenced the evolution of our galaxy. For example, the collision could have spurred a fresh burst of star formation, helping the Milky Way to grow, while the chemistry of the stars from LKH will have impacted the Milky Way's overall chemical evolution as those stars died and passed their remains into the interstellar medium to be reborn in new stars.
"Some past studies have argued that the earliest phases of our galaxy's evolution were defined by stars born only in our galaxy," said Massari. "Here, we have shown that stars born in external galaxies also need to be considered."
The discovery of the merger with LKH was reported on Aug. 17 in the journal Nature Astronomy.
Astronomers have watched a dead star, in the guise of the Helix Nebula, being recycled back into the interstellar gas from which it originally came, bringing the story of that star full circle.
Stars can last for millions, or even billions, of years, but they do not last forever. When a sun-like star reaches the end, it blossoms into a beautiful planetary nebula. The Helix Nebula, located 650 light-years away in the constellation of Aquarius, the Water Bearer, is one such example of a planetary nebula.
The Helix's central star has run out of hydrogen needed for nuclear fusion reactions in its core. This caused the core to begin to contract and raised the temperature in the star's outer layers, which ignited fusion reactions there instead. This had the effect of causing the star to bloat into a red giant. Then, eventually, the outer layers of that red giant detached and expanded into space to form the Helix Nebula. Meanwhile, the star's inert core contracted and became a white dwarf.
As the nebula expands, it gradually disperses into the interstellar medium (ISM), feeding the elements formed within the star back into interstellar gas clouds. These clouds will eventually produce the next generation of stars. However, astronomers had never actually seen the point at which a dead star's remains are absorbed into the ISM — until now.
"We are seeing material shed near the end of a star's life being broken apart and returned to the galaxy," said Yale University's Pieter van Dokkum, who led the study, in a statement. "That hand-off — from recognizable stellar debris to the diffuse gas between the stars — has been very difficult to observe."
Van Dokkum's team were not actually looking for this. Instead, they were conducting routine calibration of a new astronomical instrument called MOTHRA, the Modular Optical Telephoto Hyperspectral Robotic Array at the El Sauce Observatory in Chile. When complete, MOTHRA will be armed with 1,140 telephoto lenses that will scrutinize the night sky while looking for traces of faint gas in the Milky Way galaxy.
Astronomical instruments require calibration before use, and this is accomplished by targeting a familiar object in the sky and tuning the instruments to how that object should appear. The MOTHRA team used the Helix Nebula to calibrate the telephoto lenses that they currently have operational, and that was when they found something unexpected.
(Left) The Helix Nebula as seen by the Visible and Infrared Telescope for Astronomy. (Right) The smaller field of view from the JWST’s NIRCam (right). (Image credit: NASA, ESA, CSA, STScI, A. Pagan (STScI))
"We thought we were taking a calibration image of one of the best-known nebulas in the sky," Roberto Abraham of the University of Toronto said in the statement. "Instead, we found this extraordinary network of bow-shaped structures. It was immediately clear that the faint outer Helix was telling us a story that had largely been missed."
The Helix Nebula appears donut-shaped and has been imaged countless times before by both professional observatories such as the Hubble Space Telescope and James Webb Space Telescope, and by amateur astronomers whose long exposures can reveal an outer halo of gas around the nebula's bright ring. To give an idea of scale, the outer edge of the bright ring is 5.7 light-years across, and the outer halo exists beyond even this.
The team discovered 22 complete or partial arc-shaped clumps of gas in the outer halo. They are called bow shocks and they arise from the motion of something pressing into another medium, in this case clumps of gas that have expanded out from the planetary nebula running into and plowing through the ISM. It is similar to the bow-shaped waves that ride ahead of the prow of a boat in water.
"The shocks change dramatically with distance from the central star," Imad Pasha of Dragonfly Focused Research Organisation, said in the statement.. "Those nearer the center are large, thin and sharply defined. Further out, they become smaller, fuzzier and increasingly fragmented."
This implies a progression, and that the deeper into the ISM the clumps of the star's ejected material press, the more they become eroded and dispersed back into the interstellar gas. The team estimate that material from the planetary nebula can survive for about 10,000 years after encountering the ISM before they are completely shredded and absorbed back into it.
Stars are born from the molecular gas clouds that lie in interstellar space, and these clouds are enriched with the elements produced by fusion reactions within previous generations of stars. Now, thanks to MOTHRA's observations of the Helix Nebula, we have seen these elements being gifted to the Milky Way at large, and in millions or billions of years they will contribute to a new generation of stars, planets and possibly life.
Our own solar system, and Earth along with it, were formed 4.6 billion years ago from elements produced by dead stars. In another five billion years' time, our sun will also exhaust its supply of hydrogen and its fusion reactions will cease, causing it to unfurl into its own planetary nebula.
"Far in the future the sun will go through a similar process and its material will enter the same cycle," says van Dokkum.
All the elements and molecules that make up you and everything around you will be given back to the Milky Way, and one day it will be reborn again and begin the story of a new star system. What will that story bring, we wonder?
The findings from the Helix Nebula were published on Aug. 12 in the journal Nature.
A trio of heavyweight black holes are entangled in a dance of death that will quite possibly see them gradually all merge to form an even greater behemoth.
Scientists have discovered the black holes in a galaxy that is so far away its light has taken 12.5 billion years to reach us, meaning we see it as it was less than 1.3 billion years after the Big Bang. And it's offering strong supporting evidence that one of the ways black holes grew so massive so quickly in the early universe was through mergers.
"This is the first evidence of three active black holes in a single galaxy in the distant universe," Hannah Übler, an astronomer at the Max Planck Institute for Extraterrestrial Physics in Germany who led the study, said in a statement. "It suggests that processes in the early universe were efficient at bringing massive black holes together, setting the stage for the massive black-hole mergers we expect to detect with future gravitational-wave observatories."
The galaxy that plays host to the black holes is catalogued as J0148-4214 and is so far away (their redshift is 5.0167) that the James Webb Space Telescope (JWST), which made the discovery, could not see the black holes directly. Instead, the Integrated Field Spectroscopy unit on the JWST's Near Infrared Spectrometer (NIRSpec) measured the motion of hydrogen gas swirling around at high velocity in the accretion disks encircling each black hole.
"The JWST data allowed us not only to identify the three black holes, but also to estimate their masses, accretion rates and the stellar mass of the galaxy," Giovanni Mazzolari of the Max Planck Institute for Extraterrestrial Physics said in the statement. "We find a total stellar mass of about 1.3 billion suns, and the black holes represent a significant fraction of that."
Two of the black holes reside at the center of J0148-4214, separated by 620 light-years. One of these black holes has a huge mass of 80 million times the mass of our sun, while its companion is a relative pipsqueak at 600,000 solar masses. Yet despite its diminutive stature, the smaller black hole is growing at a tremendous rate by accreting gas faster than the Eddington limit. This is the theoretical maximum rate at which material can fall towards a black hole; if the rate is any higher then the accretion disk around the black hole becomes so dense and hot that radiation from the disk blows material back out again, stifling the black hole's feeding frenzy. This means the smaller black hole will only be able to keep growing at this rate for a short time before negative feedback calls a halt.
The third black hole is 5,500 light-years out from the center of J0148-4214 and has a mass two million times greater than the mass of our sun. This is about half the mass of the supermassive black hole at the center of our Milky Way galaxy, called Sagittarius A*. It's thought that this third black hole, and quite possibly the second one too, found their way into J0148-4214 via mergers between galaxies.
"These results are extremely exciting," said Roberto Maiolini of the University of Cambridge, who was a participant in the findings. "They suggest that black-hole merging may be an additional, fast route for their rapid growth in the early universe."
An image of Sagittarius A*, the supermassive black hole at the heart of the Milky Way. (Image credit: EHT Collaboration)
Mergers between black holes produce bursts of gravitational waves. Current gravitational-wave detectors — including The Laser Interferometer Gravitational-Wave Observatory (LIGO) in the United States, Virgo in Italy and KAGRA in Japan — are able to detect the high frequency, short wavelength gravitational waves from the mergers of stellar-mass black holes, the kind formed in certain supernova explosions. To detect the much longer wavelength, shorter frequency gravitational waves produced by the merger of supermassive black holes such as those in J0148-4214 requires a space-based detector with a baseline many millions of miles long.
To that end, the European Space Agency plans to launch LISA, the Laser Interferometer Space Antenna. If all goes to plan, by the mid-2030s. LISA will feature three spacecraft in triangular formation, each side of the triangle being 1.55 million miles (2.5 million kilometers) long. The three spacecraft will beam lasers at each other, looking for deviations in the travel time of those laser beams as evidence for the passing of a long-wavelength gravitational wave.
With regards to J0148-4214, however, there is a caveat: The third black hole might not be on a collision course with the other two. Instead, it could be heading out of the galaxy.
It's the classic three-body problem: How do three objects orbiting one another interact?
The two smaller black holes may have entered J0148-4214 as a binary pair. Then, as they were drawn closer to the 80-million-solar-mass black hole, the more massive black hole could have snatched the 600,000-solar-mass black hole while exchanging angular momentum with the two-million-solar-mass black hole to fling it away at high velocity. We see a similar effect in our galaxy with hypervelocity stars that are racing out of the Milky Way. These speedy stars used to be part of a binary pair of stars that got too close to Sagittarius A*, which is the black hole at the center of our galaxy. One half of the binary was captured by the black hole and the other was flung away.
Currently, there is no way to measure the direction of motion of the third black hole in J0148-4214 and confirm whether it will merge with the other two black holes or escape. If it did escape, it could still be wandering alone and dark in intergalactic space even now, 12.5 billion years later.
Hall was working at the U.S. Naval Observatory in Washington, D.C. and looking through a 26-inch refractor telescope — which was then the largest in the world — when he first spotted the moon. Six days earlier, he had discovered another, smaller moon that he first described as "a faint star near Mars."
Upon further inspection, not only did he realize that this star was actually the Martian moon Deimos, but he also discovered a second, larger moon now known as Phobos. He announced both discoveries the following day, on Aug. 18, 1877.
Phobos is the largest moon of Mars. Its dimensions measure 10 by 14 by 11 miles (17 by 22 by 18 kilometers) across and orbits Mars three times each Martian day at a distance of about 3,700 miles (6,000 km).
Phobos, Mars' largest moon. (Image credit: ESA/DLR/FU Berlin)
Why it mattered
Over the century and a half since this discovery, there has been an enormous amount of scientific progress in the study of Mars. In addition to many decades of studying the planet from afar, we have seen a variety of different orbiters and rovers explore the Red Planet over the past few decades. We have sampled bits of Martian material, seen up-close photos of the planet and the rocks which scatter across its surface. It might be easy to take for granted how much we know about our planetary neighbor, and this 19th century discovery was groundbreaking.
As we look to the future with new technologies and new discoveries on the horizon, it is important to also look backward to see and understand the history and work that made all of this progress possible.
Imagine orbiting hundreds of miles above Earth and seeing your home planet below — up in smoke.
That was the reality recently for astronauts aboard the International Space Station (ISS) who captured this image of the volcano Mount Rainier covered in smoke from nearby wildfires.
What is it?
This past July, hundreds of wildfires devastated a number of regions across Canada. But unfortunately, this was not the end of wildfires decimating North America this summer.
Recently, wildfires have spread across Washington and Oregon, burning over 84,000 acres (34,000 hectares) as of Aug. 12, according to NASA.
This image, captured by astronauts aboard the ISS, shows smoke blowing from wildfires in central and eastern Washington to the volcano Mount Rainier. The astronauts also captured imagery of Mt. Hood about 100 miles (160 kilometers) south. With Mt. Hood, you can also see thick plumes of smoke coming from the Grasshopper fire, which was ignited by a lightning strike.
Why is it incredible?
This is the worst fire season the Pacific Northwest has seen in over 30 years, CNN has reported. The wildfires have forced many to evacuate their homes, shut down major roads and more. In addition to the immediate dangers presented by the wildfires themselves, as we can see from these images, the smoke from the fires extends far and wide and has created unhealthy air quality levels.
As of Wednesday (Aug. 12), over 2.7 million acres (1.1 million hectares) had already burned, and by Friday (Aug. 14), the region still had dozens of uncontained wildfires, CNN reported.
While tackling the problem of wildfires — which is increasing as climate change worsens — takes place on Earth, we can learn a lot from seeing things from above. The vantage point of outer space allows for views like this, which can give a larger perspective. And satellite views can provide even more in-depth information to support wildfire fighting activities back on Earth.
A rare planet-forming disk around a young triple-star system in the Orion constellation has been tipped over by a river of gas over 1 trillion miles (1.6 trillion kilometers) long. The discovery, made at radio wavelengths with ALMA, the Atacama Large Millimeter/submillimeter Array in Chile, could explain why astronomers keep finding planets with orbits that are drastically misaligned with the rotational axes of their stars.
GW Orionis is a triple system consisting of three pre-main sequence stars, meaning that they are still forming and contracting and have not yet initiated fusion reactions of hydrogen in their core. The stars are located roughly 1,300 light-years away, in the Lambda Orionis star-forming molecular ring in the constellation of Orion, the Hunter. Finding a planet-forming disk of gas and dust encircling all three stars in a system is very rare, and finding a disk consisting of three rings with misaligned orbits is even stranger.
"Previous studies of GW Orionis revealed that the system's inner, middle and outer rings are misaligned, with each ring tilted at a different angle," said Maria Galloway-Sprietsma, a PhD student at the University of Florida who led the research, in a statement.
The outer ring, which is one of the largest ever seen around a young star, is the most noticeably misaligned. It had previously been thought that an unseen gas giant planet, having carved out a gap between the middle and outer ring, was perturbing the outer ring.
Now though, Galloway-Sprietsma and colleagues have discovered the hidden truth: an enormous finger of gas reaching in from the surrounding molecular cloud is disturbing the outer ring, and the exchange of angular momentum, or rotational energy, between the two is warping the ring and tipping it over.
The disk around GW Orionis is composed of three rings, beginning at radii of 4.1, 17.4 and 31.6 billion miles (6.7, 28 and 51 billion kilometers/44, 187 and 340 astronomical units) from the center of the tight triple system.
The streamer of gas tilting the system's outer ring was discovered through new ALMA observations. Such streamers are thought to be how stars grow, delivering mass onto nascent suns. The streamer is composed mostly of molecular hydrogen, but since molecular hydrogen is invisible at radio wavelengths, ALMA searched for molecules of carbon monoxide in the streamer instead.
The length of the streamer is astounding, stretching 0.2 light years (12,600 astronomical units, 1.9 trillion kilometers or 1.2 trillion miles).
"When our team modeled the infall of this streamer, we found that the angle at which it impacts the disk is closely aligned with the outer ring," said Galloway-Sprietsma.
This superimposed image of of the GW Orionis star system shows images from the ALMA radio telescope (in blue) overlayed on the ESO Very Large Telescope's SPHERE instrument's view, which shows the shadow of the system's innermost ring. (Image credit: ESO/Exeter/Kraus et al., ALMA (ESO/NAOJ/NRAO))
It is believed that the streamer has already done most of the work in tipping over the outer ring of the disk. Today, its angular momentum, or spin, is less than that of the disk.
"In the past it likely had a greater angular momentum, and that allowed the disk to become misaligned," said Bae.
The discovery of the streamer might put to bed more than just the mystery of what tipped over GW Orionis' disk.
In our solar system, all the planets orbit around the sun in the ecliptic plane, which is a narrow plane aligned with the sun's equator and direction of rotation. Most exoplanets orbit their star in similar fashion, but astronomers have also previously discovered some planets that have highly inclined or even retrograde orbits around their star, as though some mighty force had tipped their orbits over. With the discovery of the GW Orionis streamer, astronomers may have found the nature of the force that creates these wonky planets.
"If these streamers are common, then we can naturally explain why planets may not necessarily end up in very orderly systems," said Bae in another statement. "They can have much more random orientations."
However, the team recognizes that such a conclusion is potentially a big leap based on discovering just one planet-forming disk being influenced in such a manner. So the plan is to find more.
"What we need next is a systematic survey of young stars to see how many have streamers and how many don't," said Galloway-Sprietsma. "That will tell us how important they are in shaping planetary systems."
Chinese researchers have presented a new map of the moon, updating a previous edition based on new scientific findings and recalibrating the moon's ancient geologic eras.
The comprehensive map of the moon, with a scale of 1:5 million, was unveiled by the Institute of Geology, Chinese Academy of Geological Sciences (IGCAGS) on Aug. 6. The map is an update of a 2024 edition and puts forward new boundaries for the ancient Aitkenian, Nectarian and Imbrian lunar periods. (The researchers use the term Aitkenian, whereas the term pre-Nectarian is often used to describe the lunar geologic period from roughly around 4.5 billion to 3.9 billion years ago.)
The map also uses reprocessed spectral data to update areas of KREEP terrane, which features crustal material enriched in potassium (K), rare-earth elements (REE), and phosphorus (P), and is found to be more continuous and abundant than previously estimated.
Chinese researchers released a super-detailed new map of the moon on Aug. 6, 2026. (Image credit: CCTV/IGCAGS)
"The lunar geologic history has indeed been rewritten — more precisely, refined and systematized," the state-run outlet Xinhua quoted Yang Zhiming, director of the IGCAGS, as saying.
Both the United States, through the Apollo missions, and the Soviet Union delivered lunar samples to Earth more than 50 years ago, greatly shaping research on and understanding of the moon. China's own robotic sample return missions, Chang'e 5 and Chang'e 6, launched in 2020 and 2024, respectively, have provided fresh materials and new insights.
Chang'e 6 was the first sample-return mission to the lunar far side. Chinese researchers say the returned material will provide a new starting point for scientific discussions on the nature of that hemisphere of the moon, which is hidden from view on Earth.
The map "introduces a proprietary cartographic standard," according to Xinhua, amid a wider, Chinese government-driven initiative to influence global standards. In terms of space, aspects of the map such as the color scheme, geologic logic and an aesthetic "lighter for younger, darker for older" principle will be applied more broadly as China looks to expand its exploration beyond the moon and into the outer solar system.
"This goes beyond showcasing technological soft power. This standard will be extended to future planetary geologic mapping, establishing an independent intellectual property framework for China's deep space exploration," Yang said.
Both China and the United States have interests in setting standards as humanity renews its interest in exploring the moon. While on Earth everyone agrees on Coordinated Universal Time (UTC), the two countries currently disagree about what time it is on the moon, where clocks run faster due to weaker gravity. This suggests that leadership in space will be contested not just through missions and firsts, but via whose technical standards are followed, with China's new map playing into these efforts.
That is the takeaway of a new study examining signals from a dead star, offering what researchers say is the strongest evidence yet that extreme magnetic fields can alter the properties of a vacuum, causing seemingly empty space to act like a prism and changing how light travels through it
The findings, led by Rachael Stewart, a graduate student in physics at the George Washington University, confirm a prediction of a strange effect first proposed 90 years ago.
"The information we obtained from looking at this distant star core also gives us clues about the nature of the fabric of reality as we know it, and I find that to be incredible," Stewart said in a statement.
The idea dates to 1936, when the German physicist Werner Heisenberg and his student Hans Euler proposed that space is never truly void. Instead, they argued, it is a simmering sea of "virtual particles" — electrons and their antimatter counterparts, positrons — that flicker in and out of existence, briefly interacting with their surroundings before vanishing.
This subatomic froth is a consequence of quantum mechanics, and it remains invisible under ordinary conditions. But the theory predicts that an extremely strong magnetic field, such as one around a magnetar, can change how light moves, causing the light's waves to become more strongly aligned in a particular direction in an effect known as "vacuum birefringence."
"Detecting vacuum birefringence requires a magnetic field that is over 100 million times stronger than any we've ever made on Earth," study co-author Marcus Lower, an astrophysicist at the Swinburne University in Australia, said in another statement. "Thankfully, nature has provided us with magnetars, which are the perfect cosmic laboratories to go looking for this effect."
Magnetars are dense, city-size remnants left behind after massive stars explode, hosting the most powerful magnetic fields known in the universe. They are among the rare celestial objects capable of generating fields strong enough to reveal vacuum birefringence, offering scientists an extreme environment to test physics under conditions impossible to replicate on Earth.
"We're not just studying astronomical objects anymore; we're using them to test the laws of nature," study co-author Michela Negro, an astrophysicist at the Louisiana State University, said in a statement.
Astronomers have caught glimpses of this elusive phenomenon before, but not conclusively. In 2017, researchers using the Very Large Telescope in Chile observed polarization hints around a faint neutron star called RX J1856.5-3754, located about 400 light-years from Earth. However, those optical measurements remained open to interpretation, partly due to the challenges of isolating the optical signal.
An illustration of a magnetar. (Image credit: ESA)
At the time, scientists noted that definitive proof would require space-based X-ray observatories, specifically NASA's then-forthcoming Imaging X-ray Polarimetry Explorer (IXPE). Launched in 2021, IXPE carries three identical telescopes designed to measure the polarization of high-energy X-rays.
"It's only in the last six or so years that we've actually had a telescope capable of detecting this effect around magnetars," Lower told Michael West Media, an independent news website in Australia.
In March and April 2025, the researchers pointed IXPE at 1E 1547-5408, a magnetar that spins once every two seconds and is unusual among its kind for steadily emitting radio waves. The team supplemented that data with observations from an X-ray telescope aboard the International Space Station, as well as Australia's Murriyang radio telescope and the South African Radio Astronomy Observatory.
According to the study, two findings pointed to vacuum birefringence at work.
First, the X-rays picked up by IXPE were nearly three times more polarized than in similar sources, far higher than standard models of a neutron star's surface emission could explain on their own. Second, the polarization pointed the same way as the star's magnetic field, matching the pattern already observed in its radio waves. The researchers concluded that this combination leaves vacuum birefringence as the only explanation that fits the data.
"It's a bit of a relief because it means that our theories still work and there's nothing broken with physics," Lower told the Michael West Media news site.
An artist's depiction of the IXPE observatory in space. (Image credit: NASA)
For Fernando Camilo, chief scientist at the South African Radio Astronomy Observatory and a co-author of the new paper, the discovery brings a long journey full circle. Camilo has been studying 1E 1547-5408 since 2007, when he first detected its radio waves using the Murriyang dish, revealing its two-second rotation rate.
"At the time 1E 1547 was only the second magnetar in the Milky Way known to emit radio waves, and we were confident that regular monitoring would unveil interesting behaviour," Camilo said in the statement. "However we could never have imagined that 20 years later it would contribute to investigating a fundamental, and particularly quirky, prediction of quantum mechanics."
The team hopes to confirm the finding with data from future missions, including a proposed orbital mission called GoSOX (short for Globe Orbiting Soft X-ray Polarimeter), alongside improved computer simulations to distinguish the vacuum birefringence signal from other processes around magnetars.
"With these future data on hand and our updated simulations, we may finally be able to complete the quest started by Heisenberg nearly 90 years ago," Lower said in the Swinburne University statement.
This research is described in a paper published Aug. 5 in the journal Nature.
