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A new type of star-like object called a “dark dwarf” that could provide clues into dark matter—one of the universe’s biggest mysteries—has been proposed by an international group of scientists, led by a researcher from the University of Hawaiʻi at Mānoa.

Dark matter is an invisible substance that makes up about a quarter of the universe’s total matter. It does not emit or reflect light and can only be detected by its gravity. Despite decades of research, scientists still don’t know exactly what dark matter is.

Brown dwarfs to dark dwarfs

The study suggests that these dark dwarfs may form when brown dwarfs (small, faint “failed stars” that are too small to sustain the nuclear reactions that power normal stars) capture dark matter particles in areas where dark matter is dense, such as the center of our galaxy, the Milky Way.

Inside these dark dwarfs, the dark matter particles collide and destroy each other, releasing energy that keeps the object glowing over long periods. This energy source is different from the nuclear fusion that powers normal stars such as the Sun.

The researchers said these dark dwarfs could be identified by the presence of lithium. Lithium burns up quickly in regular stars, but would remain inside dark dwarfs, offering a way to distinguish them from brown dwarfs. Astronomers may be able to detect dark dwarfs with advanced telescopes, such as the James Webb Space Telescope, by looking for these unique signatures in the galaxy’s center.

“Finding dark dwarfs would be an important step toward understanding the true nature of dark matter and the fundamental makeup of the universe,” said Jeremy Sakstein, study lead and assistant professor in UH Mānoa’s Department of Physics and Astronomy. “Hawaiʻi’s rich tradition of astronomical research makes UH Mānoa an important hub for exploring the universe’s deepest mysteries.”

This study was published in July 2025 in the Journal of Cosmology and Astroparticle Physics.

The Department of Physics and Astronomy is housed in UH Mānoa’s College of Natural Sciences.

In a serendipitous turn of events, scientists have discovered that Japan’s Himawari-8 and Himawari-9 weather satellites, designed to monitor storms and climate patterns here on Earth, have also been quietly collecting valuable data on Venus for nearly a decade.

Although meteorological satellites orbit Earth and scan the skies around it, their imaging range extends into space, allowing them to occasionally catch glimpses of other celestial neighbors, such as the moon, stars and other planets in our solar system.

Geologists have just confirmed the Nuvvuagittuq Greenstone Belt in northern Quebec to be home to the world’s oldest known rocks studied by mankind.

The current study, spearheaded by the University of Ottawa’s Dr. Jonathan O’Neil, reiterates and validates a previous finding suggesting these dark, weathered rocks are nearly 4.16 billion years old, offering us a rare glimpse into the first chapters of Earth’s fiery past.

In Hadean Territory

Geologists study ancient rocks with zircon crystals, but this was impossible with the Nuvvuagittuq Belt, which lacks zircons due to its magnesium- and iron-rich volcanic origins.

O’Neil’s team thus turned to a rare-earth element, double-dating technique to measure the decay of samarium-146 into neodymium-142 and samarium-147 into neodymium-143. This confirmed that the belt’s metagabbros — rocks slicing like a knife into older volcanic rocks — are 4.16 billion years old.

The surrounding volcanic rocks are even more ancient, with the geologists placing them in the Hadean Eon, Earth’s least understood and earliest known geological period.

Earth’s Fiery Birth

The Hadean Eon denotes the period when our planet’s crust was still forming about 4.6 to 4 billion years ago. It was marked by relentless volcanic activity and meteor bombardments before Earth’s molten surface gradually cooled.

Nuvvuagittuq is the only known remnant to preserve such rocks from that fiery, inhospitable era. The belt’s basaltic rocks also show signs of interacting with ancient seawater, offering us tantalizing clues of Earth’s biological origins.

A Living Relic

Apart from its immense scientific value, the belt is also sacred to the Inukjuak Inuit community that inhabits the land. They worship the rocks as living relics of the past. 

Sadly, the site has suffered from overzealous sampling — some rocks have even been sold online — forcing the Inuit Pituvik Landholding Corporation to suspend all new research permits.

Image credit: Jonathan O’Neil/International Commission on Geoheritage

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Twenty-two years after the completion of the Human Genome Project, scientists have unveiled the most expansive catalog of human genetic variation ever compiled.

Across two new papers published Wednesday (July 23) in the journal Nature, scientists sequenced the DNA of 1,084 people around the world. They leveraged recent technological advancements to analyze long stretches of genetic material from each person, stitched those fragments together and compared the resulting genomes in fine detail.

Named L 98-59f, this planet is a non-transiting super-Earth with a minimal mass of 2.8 Earth masses on a 23-day orbit inside the habitable zone of the small red dwarf L 98-59.

L 98-59, also known as TOI-175, TIC 307210830, is an M dwarf about one-third the mass of the Sun.

The system lies approximately 34.5 light-years away in the southern constellation of Volans.

It features three transiting exoplanets, identified by TESS in 2019, in compact orbits of 2.25, 3.7, and 7.45 days, with an outer 12.8-day non-transiting planet confirmed in 2021 using ESO’s ESPRESSO spectrograph.

These planets exhibit a diverse range of sizes (0.8-1.6 Earth radii), masses (0.5-3 Earth mases), and likely compositions (Earth-like to possibly water-rich).

In a new study, Université de Montréal and Trottier Institute for Research on Exoplanets astronomer Charles Cadieux and his colleague carefully reanalyzed TESS, ESPRESSO, HARPS and Webb data.

They were able to determine the planets’ sizes and masses with unprecedented precision.

“We refine the radii of L 98-59b, c, and d to 0.84 Earth radii, 1.33, 1.63, respectively,” they said.

“We also report updated masses of 0.46 Earth masses for L 98-59b, 2 for L 98-59c, and 1.64 for L 98-59d, and a minimum mass of 2.82 for L 98-59e.”

The astronomers also confirmed the existence of a fifth planet, L 98-59f, in the star’s habitable zone, where conditions could allow liquid water to exist.

“Finding a temperate planet in such a compact system makes this discovery particularly exciting,” Dr. Cadieux said.

“It highlights the remarkable diversity of exoplanetary systems and strengthens the case for studying potentially habitable worlds around low-mass stars.”

“These new results paint the most complete picture we’ve ever had of the fascinating L 98-59 system,” he added.

“It’s a powerful demonstration of what we can achieve by combining data from space telescopes and high-precision instruments on Earth, and it gives us key targets for future atmospheric studies with the NASA/ESA/CSA James Webb Space Telescope.”

The refined measurements reveal nearly perfectly circular orbits for the inner planets, a favorable configuration for future atmospheric detections.

“With its diversity of rocky worlds and range of planetary compositions, L 98-59 offers a unique laboratory to address some of the field’s most pressing questions: What are super-Earths and sub-Neptunes made of? Do planets form differently around small stars? Can rocky planets around red dwarfs retain atmospheres over time?” said Université de Montréal’s Professor René Doyon, director of Trottier Institute for Research on Exoplanets.

The team’s paper will be published in the Astronomical Journal.

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Charles Cadieux et al. 2025. Detailed Architecture of the L 98-59 System and Confirmation of a Fifth Planet in the Habitable Zone. AJ, in press; arXiv: 2507.09343

MIT Professor Emeritus Keith H. Johnson, a quantum physicist who pioneered the use of theoretical methods in materials science and later applied his expertise to independent filmmaking, died in June in Cambridge, Massachusetts. He was 89.

A professor in MIT’s Department of Materials Science and Engineering (DMSE), Johnson used first principles to understand how electrons behave in materials — that is, he turned to fundamental laws of nature to calculate their behavior, rather than relying solely on experimental data. This approach gave scientists deeper insight into materials before they were made in a lab — helping lay the groundwork for today’s computer-driven methods of materials discovery.

DMSE Professor Harry Tuller, who collaborated with Johnson in the early 1980s, notes that while first-principles calculations are now commonplace, they were unusual at the time.

“Solid-state physicists were largely focused on modeling the electronic structure of materials like semiconductors and metals using extended wave functions,” Tuller says, referring to mathematical descriptions of electron behavior in crystals — a much quicker method. “Keith was among the minority that took a more localized chemical approach.”

That localized approach allowed Johnson to better examine materials with tiny imperfections called defects, such as in zinc oxide. His methods advanced the understanding of materials used in devices like gas sensors and water-splitting systems for hydrogen fuel. It also gave him deeper insight into complex systems such as superconductors — materials that conduct electricity without resistance — and molecular materials like “buckyballs.”

Johnson’s curiosity took creative form in 2001’s “Breaking Symmetry,” a sci-fi thriller he wrote, produced, and directed. Published on YouTube in 2020, it has been viewed more than 4 million times.

Trailblazing theorist at DMSE

Born in Reading, Pennsylvania, in 1936, Johnson showed an early interest in science. “After receiving a chemistry set as a child, he built a laboratory in his parents’ basement,” says his wife, Franziska Amacher-Johnson. “His early experiments were intense — once prompting an evacuation of the house due to chemical fumes.”

He earned his undergraduate degree in physics at Princeton University and his doctorate from Temple University in 1965. He joined the MIT faculty in 1967, in what was then called the Department of Metallurgy and Materials Science, and worked there for nearly 30 years.

His early use of theory in materials science led to more trailblazing. To model the behavior of electrons in small clusters of atoms — such as material surfaces, boundaries between different materials called interfaces, and defects — Johnson used cluster molecular orbital calculations, a quantum mechanical technique that focuses on how electrons behave in tightly grouped atomic structures. These calculations offered insight into how defects and boundaries influence material performance.

“This coupled very nicely with our interests in understanding the roles of bulk defects, interface and surface energy states at grain boundaries and surfaces in metal oxides in impacting their performance in various devices,” Tuller says.

In one project, Johnson and Tuller co-advised a PhD student who conducted both experimental testing of zinc oxide devices and theoretical modeling using Johnson’s methods. At the time, such close collaboration between experimentalists and theorists was rare. Their work led to a “much clearer and advanced understanding of how the nature of defect states formed at interfaces impacted their performance, long before this type of collaboration between experimentalists and theorists became what is now the norm,” Tuller said.

Johnson’s primary computational tool was yet another innovation, called the scattered wave method (also known as Xα multiple scattering). Though the technique has roots in mid-20th century quantum chemistry and condensed matter physics, Johnson was a leading figure in adapting it to materials applications.

Brian Ahern PhD ’84, one of Johnson’s former students, recalls the power of his approach. In 1988, while evaluating whether certain superconducting materials could be used in a next-generation supercomputer for the Department of Defense, Ahern interviewed leading scientists across the country. Most shared optimistic assessments — except Johnson. Drawing on deep theoretical calculations, Johnson showed that the zero-resistance conditions required for such a machine were not realistically achievable with the available materials.

“I reported Johnson’s findings, and the Pentagon program was abandoned, saving millions of dollars,” Ahern says.

From superconductors to screenplays

Johnson remained captivated by superconductors. These materials can conduct electricity without energy loss, making them crucial to technologies such as MRI machines and quantum computers. But they typically operate at cryogenic temperatures, requiring costly equipment. When scientists discovered so-called high-temperature superconductors — materials that worked at comparatively warmer, but still very cold (-300 degrees Fahrenheit), temperatures — a global race kicked off to understand their behavior and look for superconductors that could function at room temperature.

Using the theoretical tools he had earlier developed, Johnson proposed that vibrations of small molecular units were responsible for superconductivity — a departure from conventional thinking about what caused superconductivity. In a 1992 paper, he showed that the model could apply to a range of materials, including ceramics and buckminsterfullerene, nicknamed buckyballs because its molecules resemble architect Buckminster Fuller’s geodesic domes. Johnson predicted that room-temperature superconductivity was unlikely, because the materials needed to support it would be too unstable to work reliably.

That didn’t stop him from imagining scientific breakthroughs in fiction. A consulting trip to Russia after the fall of the Soviet Union sparked Johnson’s interest in screenwriting. Among his screenplays was “Breaking Symmetry,” about a young astrophysicist at a fictionalized MIT who discovers secret research on a radical new energy technology. When a Hollywood production deal fell through, Johnson decided to fund and direct the film himself — and even created its special effects.

Even after his early retirement from MIT, in 1996, Johnson continued to pursue research. In 2021, he published a paper on water nanoclusters in space and their possible role in the origins of life, suggesting that their properties could help explain cosmic phenomena. He also used his analytical tools to propose visual, water-based models for dark matter and dark energy — what he called “quintessential water.” 

In his later years, Johnson became increasingly interested in presenting scientific ideas through images and intuition rather than dense equations, believing that nature should be understandable without complex mathematics, Amacher-Johnson says. He embraced multimedia and emerging digital tools — including artificial intelligence — to share his ideas. Several of his presentations can be found on his YouTube channel.

“He never confined himself to a single field,” Amacher-Johnson explains. “Physics, chemistry, biology, cosmology — all were part of his unified vision of understanding the universe.”

In addition to Amacher-Johnson, Johnson is survived by his daughter. 

One of the main unknowns concerning interstellar objects, such as 1I/`Oumuamua, 2I/Borisov and 3I/ATLAS, is their mass. In a recent published paper, I excluded the possibility that 3I/ATLAS is an asteroid with a diameter of order 20 kilometers — as suggested by its high brightness, because detecting such a massive rock over the 5-year observing period of the ATLAS telescope is extremely unlikely. On the other hand, I showed that if 3I/ATLAS has a nucleus with a diameter smaller than 1 kilometer, then its mass would be 8,000 [=(20)³] times smaller, consistent with the expected reservoir of rocks in interstellar space. In that case, its high brightness is associated with sunlight scattered by the dust cloud surrounding it, an outer halo that carries a small fraction of its mass. If there had been a way of gauging the mass of 3I/ATLAS, this conjecture could have been tested.

Can we weigh the mass of interstellar objects? Being able to do so would also allow us to infer their mean mass density based on an independent measurement of their size.

In a new paper that I just wrote with the brilliant graduate student, Valentin Thoss, we studied the possibility of weighing interstellar objects that pass through the inner Solar System using gravitational wave observatories.

In particular, our paper studies the feasibility of probing the gravitational tide from interstellar objects roaming near Earth. Their impulsive gravitational signal is detected as their gravitational tide moves test-masses inside a gravitational wave detector relative to each other. Our calculations assess the ranges of masses, distances and velocities of interlopers to which current and future gravitational wave detectors are sensitive.

Our paper shows that the planned space observatories: Laser Interferometer Space Antenna (LISA), Big Bang Observer (BBO) and Deci-Hertz Interferometer Gravitational Wave Observatory (DECIGO), are sensitive to massive interstellar objects above the scale of 3I/ATLASS, out to distances of a few million kilometers — ten times larger than the Earth-Moon separation. The main limitation of each detector is the frequency range to which it is sensitive. In order for an encounter to be detectable, the fly-by must be sufficiently close or fast so that the peak frequency of the gravitational signal, given by the ratio between its relative velocity and distance, matches the frequency window to which the detector is sensitive.

For illustration, the following figure shows the maximum distance, R, from existing and future gravitational wave detectors, at which a fly-by of an interstellar object of mass, M, is detectable. The plot assumes an object’s velocity of 300 kilometers per second, ten times faster than the orbital speed of the Earth around the Sun or the maximum speed of conventional chemical rockets.

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The next figure shows the Signal-to-Noise Ratio (SNR) from the closest encounter expected within an observation period of 10 years, assuming that the objects make the dark matter. The SNR is shown for several gravitational wave detectors as a function of the mass, M, and velocity, v, of the objects. The red line indicates the contour for which SNR = 1.

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The likelihood for DECIGO to detect at least one event from the fly-by of compact objects, depends on their individual masses and their total local mass density in the Milky-Way. The next figure assumes an observation time of 10 years and random orbits for interstellar objects. The red shaded band corresponds to the range of the latest observational estimates of the local dark matter density. The dotted line indicates the contour of 50% detection probability, for a reduction in the expected detector noise level by a factor of 2.

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In summary, our new paper finds that if the solar system encounters dark interstellar objects with the cumulative mass density of dark matter, then future gravitational wave observatories such as DECIGO offer good prospects for detecting them in the mass window of 10–100,000 tons.

Obviously, the most interesting class of dark interstellar objects would be stealth spacecraft employed by extraterrestrial civilizations, in the style of our B-2 Spirit aircraft, to avoid detection by telescopes which rely on the reflection of sunlight from their surface. These low-albedo objects might have an unexpected appearance rate in the inner solar system if their trajectories are designed to target the habitable planets around the Sun — where the “party” of life-as-we-know-it takes place.

Gladly, gravity cannot be screened and even these stealth objects would be detectable by future gravitational wave observatories if their masses and velocities are large enough and their distance of closest approach is short enough. In that case, each data analyst working on future gravitational wave observatories could say: “Dark interstellar objects — make my day!”

ABOUT THE AUTHOR

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Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.