The research was led by PhD student Matilda Boyce and involved scientists from UWA’s School of Earth and Oceans, the University of Bristol, the Geological Survey of Western Australia, and Curtin University. Their findings were published in Nature Communications.

Studying Some of the Oldest Rocks on Earth

The team focused on anorthosites that formed about 3.7 billion years ago and were collected from the Murchison region of Western Australia. These rocks are the oldest known on the Australian continent and rank among the most ancient rocks ever discovered on Earth.

“The timing and rate of early crustal growth on Earth remains contentious due to the scarcity of very ancient rocks,” Ms Boyce said.

To overcome this challenge, the researchers used high-precision techniques to examine untouched portions of plagioclase feldspar crystals. These areas preserve the isotopic “fingerprint” of Earth’s ancient mantle, offering a rare glimpse into conditions on the early planet.

When Earth’s Continents Began to Grow

The chemical evidence suggests that Earth’s continents did not start forming immediately after the planet took shape. Instead, significant continental growth appears to have begun around 3.5 billion years ago, roughly one billion years after Earth formed.

This timeline challenges long-standing assumptions about how quickly Earth developed its continents and provides new context for understanding the planet’s early evolution.

Linking Earth and the Moon’s Origins

The researchers also compared their results with data from lunar anorthosites brought back to Earth during NASA’s Apollo missions.

“Anorthosites are rare rocks on Earth but very common on the Moon,” Ms. Boyce said.

“Our comparison was consistent with the Earth and Moon having the same starting composition of around 4.5 billion years ago.

“This supports the theory that a planet collided with early Earth and the high-energy impact resulted in the formation of the Moon.”

The study was supported by funding from the Australian Research Council.

The findings were announced at a news conference during the 247th meeting of the American Astronomical Society in Phoenix and have been accepted for publication in The Astrophysical Journal.

Eight Years of Observations Reveal a Stellar Wake

Researchers identified the influence of Siwarha by carefully measuring subtle changes in Betelgeuse’s light over nearly eight years. These long-term observations revealed the effects of a companion star that had previously been suspected but not confirmed. As the companion moves through Betelgeuse’s outer layers, it disrupts the surrounding gas, producing a trail of denser material.

This detection resolves one of the most enduring puzzles surrounding Betelgeuse. By confirming the companion’s presence, astronomers can now better explain how the star behaves and changes over time. The discovery also provides valuable insight into the later stages of evolution for other massive stars approaching the ends of their lives.

Betelgeuse is located about 650 light-years from Earth in the constellation Orion. It is a red supergiant of extraordinary size, large enough to contain more than 400 million Suns. Because it is both enormous and relatively close to Earth, Betelgeuse is one of the few stars whose surface and surrounding atmosphere can be directly studied, making it a key target for understanding how giant stars grow older, lose material, and eventually explode as supernovae.

Multiple Telescopes Confirm the Companion’s Impact

By combining data from Hubble with observations from the Fred Lawrence Whipple Observatory and the Roque de Los Muchachos Observatory, the team identified repeating patterns in Betelgeuse’s behavior. These patterns provided strong evidence of the long-suspected companion star and revealed how it affects the red supergiant’s outer atmosphere.

Scientists observed changes in the star’s spectrum, meaning the specific colors of light produced by different elements, along with shifts in the motion of gas in the outer atmosphere. These changes are linked to a dense wake formed by the companion star. The wake appears shortly after the companion passes in front of Betelgeuse approximately every six years, or about 2,100 days, in agreement with earlier theoretical predictions.

“It’s a bit like a boat moving through water. The companion star creates a ripple effect in Betelgeuse’s atmosphere that we can actually see in the data,” said Andrea Dupree, an astronomer at the CfA and lead author of the study. “For the first time, we’re seeing direct signs of this wake, or trail of gas, confirming that Betelgeuse really does have a hidden companion shaping its appearance and behavior.”

Decades of Strange Variability Explained

Astronomers have monitored Betelgeuse for decades, tracking changes in its brightness and surface features in an effort to understand its unpredictable behavior. Interest surged in 2020 when the star unexpectedly dimmed after what was described as a stellar “sneeze.” Scientists identified two major cycles in Betelgeuse’s variability: a shorter 400-day period linked to pulsations inside the star, and a much longer cycle lasting about 2,100 days.

Before this discovery, scientists explored many explanations for Betelgeuse’s long-term changes. These included massive convection cells, clouds of dust, magnetic activity, and the potential influence of a hidden companion. Recent studies suggested that the longer cycle was best explained by a low-mass star orbiting deep within Betelgeuse’s atmosphere. Although one group reported a possible detection, there was no definitive evidence until now.

The newly detected wake provides the strongest proof yet that a companion star is actively disturbing the atmosphere of this red supergiant.

“The idea that Betelgeuse had an undetected companion has been gaining in popularity for the past several years, but without direct evidence, it was an unproven theory,” said Dupree. “With this new direct evidence, Betelgeuse gives us a front-row seat to watch how a giant star changes over time. Finding the wake from its companion means we can now understand how stars like this evolve, shed material, and eventually explode as supernovae.”

Looking Ahead to Future Observations

From Earth’s perspective, Betelgeuse is currently eclipsing its companion star. Astronomers are planning additional observations when the companion becomes visible again in 2027. Researchers say this discovery could also help solve similar mysteries involving other giant and supergiant stars.

Hubble’s Continuing Contributions

The Hubble Space Telescope has been operating for more than 30 years and continues to produce discoveries that deepen our understanding of the universe. Hubble is a collaborative project between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, oversees mission operations, with additional support from Lockheed Martin Space in Denver. The Space Telescope Science Institute in Baltimore, operated by the Association of Universities for Research in Astronomy, manages Hubble’s scientific operations for NASA.

“This is a tale of a failed galaxy,” said the program’s principal investigator, Alejandro Benitez-Llambay of the Milano-Bicocca University in Milan, Italy. “In science, we usually learn more from the failures than from the successes. In this case, seeing no stars is what proves the theory right. It tells us that we have found in the local Universe a primordial building block of a galaxy that hasn’t formed.”

A Rare Glimpse of the Dark Universe

“This cloud is a window into the dark Universe,” explained team member Andrew Fox of AURA/STScI for the European Space Agency. “We know from theory that most of the mass in the Universe is expected to be dark matter, but it’s difficult to detect this dark material because it doesn’t emit light. Cloud-9 gives us a rare look at a dark-matter-dominated cloud.”

Cloud-9 belongs to a category known as Reionization-Limited H I Clouds, or “RELHICs.” The term “H I” refers to neutral hydrogen, while “RELHIC” describes a hydrogen cloud formed in the early Universe that never progressed to form stars. Scientists had predicted the existence of such objects for years, but direct confirmation remained elusive. Only after observing Cloud-9 with Hubble were researchers able to verify that it truly contains no stars.

Ruling Out a Hidden Dwarf Galaxy

“Before we used Hubble, you could argue that this is a faint dwarf galaxy that we could not see with ground-based telescopes. They just didn’t go deep enough in sensitivity to uncover stars,” explained lead author Gagandeep Anand of the Space Telescope Science Institute (STScI), Baltimore, USA. “But with Hubble’s Advanced Camera for Surveys, we’re able to nail down that there’s nothing there.”

The discovery itself caught researchers off guard. “Among our galactic neighbors, there might be a few abandoned houses out there,” said STScI’s Rachael Beaton, who is also on the research team.

RELHICs are believed to be dark matter structures that never gathered enough gas to trigger star formation. Because of this, they preserve conditions from the early Universe. Cloud-9 points to the likely existence of many other small, dark matter-dominated objects, often described as failed galaxies. Studying them offers new insight into parts of the Universe that remain difficult to observe because most telescopes focus on bright stars and galaxies.

Measuring an Invisible Giant

Hydrogen clouds near the Milky Way have been studied for decades, but most are far larger and more irregular in shape than Cloud-9. By contrast, Cloud-9 is smaller, denser, and nearly spherical, giving it a distinctly different appearance from other known gas clouds.

At its center, Cloud-9 contains neutral hydrogen spanning roughly 4900 light-years. The hydrogen gas alone has a mass about 1 million times that of the Sun. If the gas pressure is indeed balanced by the gravitational pull of the surrounding dark matter, then dark matter must account for most of the object’s mass. Based on this balance, Cloud-9 is estimated to contain roughly 5 billion solar masses.

Why Starless Objects Matter

Cloud-9 highlights how much of the Universe exists beyond stars. Observing starlight alone does not reveal the full picture. By examining gas and dark matter together, scientists can better understand systems that would otherwise remain hidden.

Finding failed galaxies like Cloud-9 is difficult because nearby bright objects often overpower their faint signals. These systems are also sensitive to environmental effects such as ram-pressure stripping, which can remove gas as they move through intergalactic space. These challenges help explain why such objects appear to be rare.

Discovery Through Radio Telescopes

Cloud-9 was first detected three years ago during a radio survey conducted with the Five-hundred-meter Aperture Spherical Telescope (FAST) in Guizhou, China. The discovery was later confirmed using the Green Bank Telescope and the Very Large Array in the United States. The name “Cloud-9” carries no cultural meaning in China and was assigned simply because it was the ninth gas cloud identified near the outer regions of the spiral galaxy Messier 94 (M94).

The cloud lies close to M94 and appears to be physically connected to the galaxy. High-resolution radio observations reveal slight distortions in the gas, which may be evidence of interaction between Cloud-9 and its larger neighbor.

A Galaxy That Might Still Form

Whether Cloud-9 will eventually become a galaxy depends on whether it gains additional mass. If it had been much larger, gravity would have caused it to collapse and form stars long ago. If it were much smaller, its gas might have dispersed and become ionized, leaving little behind. Instead, it exists in a narrow range that allows it to persist as a RELHIC.

This discovery advances understanding of how galaxies form, how the early Universe evolved, and how dark matter behaves. Because Cloud-9 contains no stars, it allows scientists to study the properties of dark matter clouds without interference from starlight. As future surveys improve, researchers expect to uncover more of these rare relics, offering deeper insight into the Universe’s hidden structure and the physics of dark matter.

Expanded DNA repeats are responsible for more than 60 inherited disorders. These conditions develop when repeating genetic sequences lengthen beyond normal limits and interfere with healthy cell function. Examples include Huntington’s disease, myotonic dystrophy, and certain forms of ALS.

Although most people carry DNA repeats that slowly expand throughout life, scientists had not previously examined how widespread this instability is or which genes control it using large biobank datasets. This research shows that repeat expansion is far more common than previously recognized. It also identifies dozens of genes involved in regulating the process, creating new opportunities to develop treatments that could slow disease progression.

How Researchers Studied Nearly a Million Genomes

The research team, which included scientists from UCLA, the Broad Institute, and Harvard Medical School, analyzed whole genome sequencing data from 490,416 participants in the UK Biobank and 414,830 participants in the All of Us Research Program. To carry out the analysis, they developed new computational approaches capable of measuring DNA repeat length and instability using standard sequencing data.

Using these tools, the team examined 356,131 variable repeat sites across the human genome. They tracked how repeat lengths changed with age in blood cells and identified inherited genetic variants that affected the speed of expansion. The researchers also searched for associations between repeat expansion and thousands of disease outcomes in order to uncover previously unknown links to human illness.

Key Findings on DNA Repeat Instability

The study found that common DNA repeats in blood cells consistently expand as people get older. Researchers identified 29 regions of the genome where inherited genetic variants altered repeat expansion rates, with differences of up to fourfold between individuals with the highest and lowest genetic risk scores.

One surprising result was that the same DNA repair genes did not behave uniformly. Genetic variants that helped stabilize some repeats made other repeats more unstable. The researchers also identified a newly recognized repeat expansion disorder involving the GLS gene. Expansions in this gene, which occur in about 0.03% of people, were linked to a 14-fold increase in the risk of severe kidney disease and a 3-fold increase in the risk of liver diseases.

What the Findings Mean for Future Research

The results suggest that measuring DNA repeat expansion in blood could serve as a useful biomarker for evaluating future treatments designed to slow repeat growth in diseases such as Huntington’s. The computational tools developed for this study can now be applied to other large biobank datasets to identify additional unstable DNA repeats and related disease risks.

Researchers note that further mechanistic studies will be needed to understand why the same genetic modifiers can have opposite effects on different repeats. These efforts will focus on how DNA repair processes differ across cell types and genetic contexts. The discovery of kidney and liver disease linked to GLS repeat expansion also suggests that additional, previously unrecognized repeat expansion disorders may be hidden within existing genetic data.

Expert Perspective on the Findings

“We found that most human genomes contain repeat elements that expand as we age,” said Margaux L. A. Hujoel, PhD, lead author of the study and assistant professor in the Departments of Human Genetics and Computational Medicine at the David Geffen School of Medicine at UCLA. “The strong genetic control of this expansion, with some individuals’ repeats expanding four times faster than others, points to opportunities for therapeutic intervention. These naturally occurring genetic modifiers show us which molecular pathways could be targeted to slow repeat expansion in disease.”

Margaux L. A. Hujoel (UCLA and Brigham and Women’s Hospital/Harvard Medical School), Robert E. Handsaker (Broad Institute and Harvard Medical School), David Tang (Brigham and Women’s Hospital/Harvard Medical School), Nolan Kamitaki (Brigham and Women’s Hospital/Harvard Medical School), Ronen E. Mukamel (Brigham and Women’s Hospital/Harvard Medical School), Simone Rubinacci (Brigham and Women’s Hospital/Harvard Medical School and Institute for Molecular Medicine Finland), Pier Francesco Palamara (University of Oxford), Steven A. McCarroll (Broad Institute and Harvard Medical School), Po-Ru Loh (Brigham and Women’s Hospital/Harvard Medical School and Broad Institute)

M.L.A.H. was supported by US NIH fellowship F32 HL160061; R.E.H. and S.A.M. by US NIH grant R01 HG006855; D.T. by US NIH training grant T32 HG002295; N.K. by US NIH training grant T32 HG002295 and fellowship F31 DE034283; R.E.M. by US NIH grant K25 HL150334; S.R. by a Swiss National Science Foundation Postdoc. Mobility fellowship; P.F.P. by ERC Starting Grant no. 850869; and P.-R.L. by US NIH grants R56 HG012698, R01 HG013110 and UM1 DA058230 and a Burroughs Wellcome Fund Career Award. The All of Us Research Program is supported by the NIH. The authors declare no competing interests.