Space & Physics
An abundance crisis in the early universe
Astrophysicists are finding more ultra massive galaxies in JWST data than ever before.
In a paper published in Physical Review Letters, astrophysicists argue that present galaxy evolution models don’t need to be fundamentally changed, beyond some tweaks. Julian Muñoz, one of the paper’s co-authors, worked out calculations to correct for galaxies to form and grow quicker in the early universe.
In a Physics.org report, Muñoz praised James Webb Space Telescope’s (JWST) contribution. “We’re opening a window to the unknown,” said Muñoz, an astrophysicist and assistant professor at the University of Texas, Austin, US. “We are now able to test our theories about the universe where we haven’t been able to before.”
There is no need though for cosmologists to abandon galaxy evolution models yet. It’s only in need of some tweaks. It’s perfectly fine for physical models to undergo modifications of key assumptions from time to time, without sacrificing the sacred tenets of the model itself. In fact, the currently accepted cosmological theory of our universe – the Lambda-Cold Dark Matter model (or Lambda-CDM for short) – matches observations for galaxy formation in the most recent past of the universe’s evolution.
There have been other papers too, tacking this abundance problem, ever since JWST’s began detections in the summer of 2022. JWST had detected either more galaxies, or massive galaxies than theorized in earlier epochs.
However, it’s neither clear whether it is massive galaxies that JWST is observing, nor are they from the earlier epochs.
Due to JWST’s limited spectra resolution, astrophysicists are in dire need to reinforce findings with data from ground based radio telescopes to train their dishes on these newly discovered galaxies over a large observation period.
The co-authors of the paper include Nashwan Sabti and Marc Kamionkowski from John Hopkins University (JHU), Baltimore, US. The research was funded by the US National Science Foundation (NSF), Simons Foundation and JHU’s Horizon Fellowship (for Nashwan Sabti).
Space & Physics
Sophie Adenot Makes History as First Frenchwoman to Walk in Space
French astronaut Sophie Adenot has become the first Frenchwoman to perform a spacewalk, spending 6 hours 23 minutes outside the International Space Station.
French astronaut Sophie Adenot has become the first Frenchwoman to perform a spacewalk, spending 6 hours and 23 minutes outside the International Space Station to begin repairs to its exterior communications system.
French astronaut Sophie Adenot made European space history on Tuesday by becoming the first French woman to perform a spacewalk outside the International Space Station. Adenot, 44, stepped outside the orbiting laboratory alongside American astronaut Anil Menon, floating roughly 400 kilometres above the Earth for 6 hours and 23 minutes to begin a repair of the station’s exterior communications equipment.
“I’m out,” Adenot said as she exited the station. “I feel very good now.”
A Repair Job That Ran Long The astronauts’ task was to replace an aging space-to-ground antenna on the station’s Z1 truss — the primary link carrying high-speed data, voice calls and video between the station and mission control in Houston. The antenna had stopped tracking NASA’s data relay satellites since November and had been out of service since, with a second antenna carrying the station’s communications load in the meantime.
Menon and Adenot successfully removed the failed antenna and secured it to the truss structure, but disconnecting its electrical cables and loosening its mounting bolts took longer than planned, leaving no time to install the replacement unit. NASA has scheduled a second spacewalk for Tuesday, August 25, to complete the installation. The station’s communications were not affected by the delay, as the backup antenna continued operating throughout.
Inside the station, astronauts Jack Hathaway and Jessica Meir coordinated the operation from the control desk, operating the station’s robotic arm and monitoring the spacewalkers’ life support systems throughout.
Days of Preparation Before the Hatch Opened Spacewalks demand days of preparation before the airlock ever opens. In the lead-up, Adenot and Menon spent dozens of hours readying their gear inside the station — inspecting safety tethers, organising tools, servicing backup emergency jetpacks, charging suit batteries, checking for pressure leaks, and testing biomedical sensors and radios.
Spacewalk complete. ✅
After 6 hours and 23 minutes outside the International Space Station, @Soph_astro is safely back inside.
With today’s EVA, Sophie becomes the first French woman to perform a spacewalk. 🇫🇷 pic.twitter.com/i3BghrdaRK— European Space Agency (@esa) August 18, 2026
“A successful [spacewalk] starts long before the hatch opens, and that’s where my focus has been these past few days: rehearsing, preparing and focusing,” Adenot said on social media before the excursion.
Suit fitting was a major focus of the preparation: working inside a heavy, pressurised spacesuit for over six hours puts considerable strain on an astronaut’s hands and shoulders, and engineers on the ground worked closely with Adenot to customise her suit and reduce pressure points.
A Milestone for European Space Exploration Adenot brought extensive technical experience to the mission. A trained engineer and former helicopter test pilot, she was selected for astronaut training by the European Space Agency in 2022 and launched to the space station in February 2026, becoming only the second French woman in history to reach space, after physician-astronaut Claudie Haigneré in 1996. With Tuesday’s spacewalk, she also became the second European woman ever to conduct a spacewalk, after Italian astronaut Samantha Cristoforetti in 2022, and the fifth French citizen overall to do so. The last French citizen to walk in space was Thomas Pesquet.
Despite the milestone, Adenot credited the wider team behind the mission. “My deepest gratitude goes to everyone who made this possible — pioneers who came before us, but also the incredible teams working behind the scenes today,” she said after returning inside the station.
Space & Physics
Hubble and Gaia Uncover Evidence of Ancient Dwarf Galaxy Devoured by the Early Milky Way
Hubble and Gaia reveal evidence of an ancient Milky Way merger with a dwarf galaxy about 11.8 billion years ago, reshaping our understanding of the galaxy’s origins.
A Milky Way merger with a dwarf galaxy about 11.8 billion years ago has been uncovered by astronomers using the Hubble Space Telescope and ESA’s Gaia mission. The discovery provides new evidence about how the Milky Way formed and identifies a distinct population of ancient globular clusters linked to the merger.
Our home galaxy, the Milky Way, contains hundreds of billions of stars today. It grew to this size over billions of years by pulling in smaller neighbouring galaxies and absorbing them. Now, astronomers using the NASA/ESA Hubble Space Telescope and ESA’s Gaia mission have found evidence of a major merger that occurred near the very beginning of the Milky Way’s history.
By combining precise stellar age and chemical-composition measurements from Hubble with motion-mapping data from Gaia, the team pushed back the known timeline of the Milky Way’s formation by roughly 1.8 billion years. The findings, led by Davide Massari of the Astrophysics and Space Science Observatory of Bologna, Italy, were published this week in Nature Astronomy.
Evidence of an Ancient Milky Way Merger
Reconstructing the Milky Way’s earliest history is difficult: in its youth, the galaxy was smaller, more chaotic, and closer in size to the dwarf galaxies it collided with, and many physical traces of those early mergers have since been erased.
To work around this, the researchers studied 39 globular clusters — dense, ancient groupings of up to a few million stars — in the inner 20,000 light-years of the galaxy, where evidence of the earliest mergers is most likely to survive. Using Hubble’s high-resolution imaging, the team measured each cluster’s age and metallicity (its abundance of elements heavier than helium) with what the researchers describe as unprecedented precision.
“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 Chiara Zerbinati, a co-author on the study at the University of Bologna, in a release issued by ESA Hubble. “Coupled with measurements from Gaia, this made it possible to distinguish a population of globular clusters that are different from the others.”
Identifying LKH
Cross-referencing Hubble’s age and metallicity data with Gaia’s motion measurements, the researchers identified a distinct third population of globular clusters — older than the ones known to have arrived during the Milky Way’s collision with the Gaia-Sausage-Enceladus dwarf galaxy about 10 billion years ago, but younger than the stars that formed within the Milky Way itself.
That pattern pointed to a separate, earlier merger: the absorption of a dwarf galaxy roughly 11.8 billion years ago — about two billion years after the Big Bang — carrying a total stellar mass of around 500 million times the mass of the Sun, a significant share of the Milky Way’s total mass at the time.
The researchers named the dwarf galaxy Low-energy-Kraken-Heracles, or LKH, after three earlier papers that had proposed the idea of an early merger in the Milky Way’s history.
“Our home is the Milky Way galaxy, but we do not know how our house was built,” Massari said. “In this paper we discover where the first significant batch of bricks came from: a dwarf galaxy that we call LKH.”
Rewriting Early Galactic History
The finding challenges an earlier assumption that the Milky Way’s oldest stellar populations formed almost entirely in place, showing instead that external galaxies contributed to its structure far earlier than previously established.
The team plans to extend the analysis to additional globular clusters across the galaxy, aiming to build a more complete map of the mergers that shaped the Milky Way over cosmic history.
Space & Physics
Total Solar Eclipse 2026: What Happened and Where Was It Visible?
The August 12, 2026 total solar eclipse saw the Moon completely cover the Sun along a narrow path across parts of Greenland, Iceland, northern Russia, Spain and Portugal. While much of Europe and parts of North America and northwestern Africa experienced a partial eclipse, the event was not visible from India.
On August 12, the Moon passed between the Sun and Earth, producing a total solar eclipse. Along a narrow path, the Moon completely covered the Sun, briefly darkening the daytime sky. Much of Europe and parts of North America and northwestern Africa saw a partial eclipse.
A solar eclipse occurs when the Moon passes between the Sun and Earth and casts its shadow on Earth’s surface. Because the Moon’s darkest shadow covers only a limited area, an eclipse can be total in one region, partial in another and invisible elsewhere.
Why did some places go dark?
The Moon casts two main shadows during a solar eclipse. The umbra is the central shadow, where the Sun is completely blocked. People within it experience totality.
The penumbra extends beyond the umbra. People in this larger region see only part of the Sun covered and therefore experience a partial eclipse.
This is why the same eclipse looks different from different locations. A place inside the path of totality can experience a few minutes of daytime darkness, while a location farther away may see only a portion of the Sun covered.
Where was the eclipse visible?
Totality was visible across parts of Greenland, Iceland, northern Russia, Spain and northeastern Portugal, as well as parts of the Atlantic and Arctic oceans.
A much larger area experienced a partial eclipse. This included much of Europe, parts of North America and northwestern Africa, along with areas over the Atlantic, Arctic and Pacific oceans.
For mainland Europe, the event was particularly notable because it brought totality to the region for the first time since 1999.
Why couldn’t India see it?
India was outside the eclipse’s visibility zone. The eclipse’s path of totality was concentrated much farther north, and India was not within the region from which the August 12 event could be observed.
This illustrates an important point about solar eclipses: an eclipse may occur over Earth without being visible from a particular country. The Moon’s shadow covers only a limited part of the planet.
How often do solar eclipses occur?
Solar eclipses are not exceptionally rare. There are generally two to five solar eclipses somewhere on Earth each year.
However, a total solar eclipse at a particular location is much rarer. A 2026 analysis by timeanddate estimates that, on average, a total solar eclipse occurs at a given location about once every 373 years. The actual interval can vary considerably between locations.
The reason is the geometry of the Moon’s orbit. It is tilted by about five degrees relative to Earth’s orbit around the Sun, so the Moon usually passes above or below the Sun rather than directly in front of it. Only when the alignment is sufficiently close does its shadow fall across Earth.

Why are total solar eclipses scientifically important?
During normal daylight, the Sun’s bright surface makes its faint corona difficult to observe. During totality, the Moon blocks the bright disk, revealing the corona around it.
Scientists study the corona to better understand the Sun’s atmosphere, magnetic activity and solar wind. These processes are also important to the study of space weather, which can affect satellites and communications.
The August 12 eclipse was therefore more than a striking change in the daytime sky. For observers along its narrow path, a few minutes of darkness provided a rare opportunity to see the Sun’s outer atmosphere—while much of the world saw only a partial eclipse or nothing at all.
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