Category: 7. Science

Cosmologists at Durham University, UK, used a new technique combining the highest-resolution supercomputer simulations that exist, alongside novel mathematical modelling, predicting the existence of missing “orphan” galaxies.

Their findings suggest that there should be 80 or perhaps up to 100 more satellite galaxies surrounding our home galaxy, orbiting at close distances.

If these galaxies are seen by telescopes then it could provide strong support for the Lambda Cold Dark Matter (LCDM) theory which explains the large-scale structure of the Universe and how galaxies form.

This ongoing research is being presented at the Royal Astronomical Society’s National Astronomy Meeting being held at Durham University.

The Durham-led research is based on the LCDM model where ordinary matter in the form of atoms represents only 5% of the Universe’s total content, 25% is cold dark matter (CDM), and the remaining 70% is dark energy.

In this model, galaxies form in the centre of gigantic clumps of dark matter called halos. Most galaxies in the Universe are low-mass dwarf galaxies, the majority of which are satellites orbiting around a more massive galaxy, such as our Milky Way.

The existence of these enigmatic objects has long posed challenges to LCDM – otherwise known as the standard model of cosmology. According to LCDM theory, many more Milky Way companion galaxies should exist than cosmological simulations have so far produced, or astronomers have been able to see.

The new research shows that the Milky Way’s missing satellites are extremely faint galaxies stripped almost entirely of their parent dark matter halos by the gravity of the Milky Way’s halo. These so-called “orphan” galaxies are lost in most simulations, but should have survived in the real Universe.

Using their new technique, the Durham researchers were able to track the abundance, distribution, and properties of these Milky Way orphan galaxies – showing that many more Milky Way satellites should exist and be observable today. It is hoped that new advances in telescopes and instruments like the Rubin Observatory LSST camera (which recently saw its first light), will give astronomers the ability to detect these very faint objects, bringing them into our view for the first time.

Lead researcher Dr Isabel Santos-Santos, in the Institute for Computational Cosmology, Department of Physics, Durham University, said: “We know the Milky Way has some 60 confirmed companion satellite galaxies, but we think there should be dozens more of these faint galaxies orbiting around the Milky Way at close distances.

“If our predictions are right, it adds more weight to the Lambda Cold Dark Matter theory of the formation and evolution of structure in the Universe.

“Observational astronomers are using our predictions as a benchmark with which to compare the new data they are obtaining.

“One day soon we may be able to see these ‘missing’ galaxies, which would be hugely exciting and could tell us more about how the Universe came to be as we see it today.”

The concept of LCDM is the cornerstone of our understanding of the Universe. It has led to the Standard Model of Cosmology and is the most widely accepted model for describing the Universe’s evolution and structure on large scales.

The model has passed multiple tests but has recently been challenged by puzzling observational data on dwarf galaxies.

The Durham researchers say that even the best existing cosmological simulations (which include gas and star formation, in addition to dark matter) do not have the resolution needed to study galaxies as faint as those astronomers are starting to discover close to the Milky Way.

These simulations also lack the precision required to follow the evolution of the small dark matter halos that host the dwarf galaxies as they orbit around the Milky Way over billions of years.

This leads to the artificial disruption of some halos, leaving galaxies “orphaned.” Although the simulations lose the halos of “orphan” galaxies, such galaxies should survive in the real Universe.

The Durham researchers combined cosmological supercomputer simulations with analytical models to overcome these numerical issues.

This included the Aquarius simulation, produced by the Virgo Consortium. Aquarius is the highest resolution simulation of a Milky Way dark matter halo ever created and is used to understand the fine-scale structure predicted around the Milky Way.

It also included the GALFORM model, a cutting-edge code developed at Durham over the past two decades which follows the detailed physical processes that are responsible for the formation and evolution of galaxies.

Their results showed that halos of dark matter, which may host a satellite galaxy, have been orbiting around the central Milky Way halo for most of the age of the Universe, leading to the stripping of their dark matter and stellar mass, and rendering them extremely small and faint.

As a result, the research predicts that the total number of satellite galaxies – of any brightness – likely to exist around the Milky Way is around 80 or potentially up to 100 more than currently known.

The research puts particular emphasis on the approximately 30 newly discovered tiny Milky Way satellite candidates that are extremely faint and small.

Scientists are unclear if these are dwarf galaxies embedded in a dark matter halo, or globular clusters, collections of self-gravitating stars.

The Durham researchers argue that these objects could be a subset of the faint population of satellite galaxies they predict should exist.

Co-researcher Professor Carlos Frenk, of the Institute for Computational Cosmology, Department of Physics, Durham University said: “If the population of very faint satellites that we are predicting is discovered with new data, it would be a remarkable success of the LCDM theory of galaxy formation.

“It would also provide a clear illustration of the power of physics and mathematics. Using the laws of physics, solved using a large supercomputer, and mathematical modelling we can make precise predictions that astronomers, equipped with new, powerful telescopes, can test. It doesn’t get much better than this.”

The research is funded by the European Research Council through an Advanced Investigator grant to Professor Frenk, and by the Science and Technology Facilities Council (STFC). The calculations were performed on the Cosmology Machine (COSMA), a supercomputer supported by the STFC’s Distributed Infrastructure for Research using Advanced Computing (DiRAC) project, and hosted by Durham University.

The Royal Astronomical Society’s (RAS) National Astronomy Meeting 2025 (NAM 2025) is being held at Durham University from 7-11 July.

Almost a thousand of the world’s top astronomers and space scientists will attend NAM which sees researchers present the latest cutting-edge space research alongside outreach events involving schools, artists, industry and the public.

What a show! On July 2^nd, 2025, 23h 50min UT (which equals July 3^rd, 00h 50min BST) a dramatic fireball enlighted Scottish skies and was reported by nearly 150 people all over Great Britain and Ireland (Event #3666-2025, Figure 1). From recordings, meteorites must survive the atmospheric entry of the big meteoroid, but first prospections on the theoritical strewn field show their recovery will be complicated.

If you witnessed this event and/or if you have a video or a photo of it, please
Submit an Official Fireball Report

If you want to learn more about Fireballs: read our Fireball FAQ.

A fireball as bright as the Full Moon widely observed from United Kingdom and Ireland

Happy were the people located in United Kingdom and Ireland looking at the sky on July 2-3 night! On July 2^nd, 2025, 23h 50min UT (which equals July 3^rd, 00h 50min BST), those skies briefly turned out bright!  A very bright (mag. -12.2 according to UKMON, GMN and Jamie Shepherd team calculations, to compare to -12.6 magnitude of a full Moon!) and long-lasting (more than 12 seconds!) fireball fragmented several times, enlighting its luminous path with very bright flares.  Event was observed and reported by nearly 150 people all over United Kingdom and Ireland (Event #3666-2025, Figure 1), and many people managed to record it on video (Figures 4 & 5, and see below), as well as UK Meteor Network (UKMON), Global Meteor Network (GMN) and Fripon (Fireball Recovery and InterPlanetary Observation Network) video networks did (Figures 2 & 3). Light was so important, that it blinded a lot of cameras during the brightest part of the meteor (Figure 2).

Video by David Pauling (Great-Britain, report #3666eq-2025):

Video by James Hail from Glenfinnan (Great-Britain, report #3666eq-2025), showing the brightness on the ground:

Video by Robert (Great-Britain, report #3666eu-2025), allowing the comparison between the fireball brightness and a city floor lamp:

Video from ABC News:

Determining the atmospheric trajectory of the fireball…

Thanks to all these recordings, a UKMON/GMN team leaded by Jamie Shepherd calculated the physical parameters of the meteoroid that was at the origin of the sporadic fireball, as well as its atmospheric trajectory. According to them, the meteoroid, coming from the inner parts of the main asteroid belt (Figure 6)  weighted a bit more than 60 kg before it entered the atmosphere. It entered the Earth atmosphere with a 12.3 km/s (nearly 44 300 km/h) and a 31.3° inclination relative to the horizontal.

The meteor started being visible as it was 97 km above the ground, 15 km West of Hebrides islands (lat. ~ 56.70° N ; lon. ~ 6,70° W). It then travelled on a nearly Eastern trajectory (azimuth ~83°) which measures nearly 120 km, bringing it to shine above the grounds of Scotland, ending its visible path when it was below 25 km in altitude, nearly above Loch Treig (lat. ~ 56.81° N ; lon. ~ 4,77° W, figures 7 & 8).

…to try to located the position and extension of a meteorites strewn field!

From witnesses reports and video recordings, the meteoroid highly fragmented during its atmospheric entry ; some witnesses also reported having heard sonic booms after the display. According to calculations, some kilograms of meteorites could have landed on the ground. Unfortunately, the land access and physical properties of the ground itself make the potential recovery of meteorites very complicated.

Bill Ward, using his own calculated strewn field calculated from visual reports and GMN video recordings, tried to go on site to see if he could by chance find anything. Here is his report of this difficult day clearly showing how harsh the recovery conditions are: “After your email I thought it would be worth a hike…. This proved to be a huge mistake as the terrain was much worse than I thought. Despite the low probability of success (and the estate manager not releasing the code for the main gate so I had to go cross country.) The the high rainfall has left the ground saturated and I couldn’t even get close to the main strewn field (or where I thought it might be). I’ve attached a zip file with two pictures. The first (Figure 9) is a general view of the estimated strewn field, starting just over the rise of ground in the fore ground running half way up the mountain, background left, maybe 5 to 10km. The second (Figure 10) is the type of terrain in the valley of the main fall area.  If anyone recovers any meteorites from this type of ground then they have had immense luck. The closest I got to a fusion crust was finding some animal droppings, either from a deer or a very, very large rabit! After 6 hours I was exhausted and I struggled to cross the wet ground to get back to my car. Sunburned, battered and bruised by falling so often in the swamp with fallen trees, blistered feet, and bitten by bugs, the next meteorite hunt I go on will be if one lands in my back garden! A VERY long day!”

Last update: July 13th, 2025, 14h 50min UT

The annual Perseid meteor display is one of the best-known and commonly observed meteor showers in the Northern Hemisphere. But this year, if you want to enjoy the show, it’s best to get in early.

The Perseids will be active from Thursday, July 17, through Saturday, Aug. 23 and will peak this year on Aug. 12 and 13. But the presence of a near-full moon will make this year’s event disappointing, with only the very brightest shooting stars visible.

Human engineering appears to have moved the planet, literally. According to new research published this month, the global boom in dam construction over the past two centuries has caused measurable shifts in Earth’s poles. The data shows that it has even led to a small but significant drop in sea levels.

To truly understand how it has affected our planet, we first have to look at how the Earth’s outer crust works. The crust floats on what is essentially a layer of molten rock, which means that the it can move when mass shifts around the planet’s surface. Scientists call this wobbling true polar wander.

While this phenomenon does happen naturally — such as when glaciers grow or melt — researchers have now shown that human-made dams also shift the Earth’s poles. A better way to think about it is to imagine that you stick a lump of clay on a basketball as it spins. As the ball moves, it slowly adjusts to account for the new weight. On Earth, the outer crust works similarly, realigning itself and our geographic poles, resulting in a slower drift for the planet.

This new study looked at data from over 6,862 dams built between 1835 and 2011. Together, these dams store enough water to fill the Grand Canyon twice, the researchers note. And that trapped water isn’t just sitting there, having no effect on our world. Not only did these dams remove volume from the oceans (dropping global sea levels by about 21 millimeters) but the filling of these dams also shifted mass on land, causing the Earth’s poles to move by roughly 1.1 meters (3.7 feet).

The researchers identified two major phases of dam construction that shifted Earth’s poles in the past. From the 1800s to mid-1900s, dam building in North America and Europe pulled the North Pole slightly toward Asia. However, from the 1950s onward, large dams in Africa and Asia shifted the pole back toward western North America. While these shifts in Earth’s poles are small on a global scale, they matter quite a bit to understanding our planet and its various systems.

For starters, the redistribution of water greatly affects how scientists model sea level rise. During the 20th century, sea levels rose an average of 1.2 millimeters per year — but about a quarter of that was offset by dams holding water on land. Even more important, though, is the fact that wherever water is stored can change the pattern of sea level rise. Some regions may see higher or lower increases in the sea level depending on dam placement.

This research is just one part of a growing list of evidence that human actions are completely reshaping Earth in massive ways. As climate change drives further glacier melt and sea level rise, tracking how mass moves across the planet will be crucial to understanding not just our oceans, but ongoing shifts in Earth’s poles. Especially those caused by human intervention.

As the weight of melting ice is lifted off volcanos, eruptions will become more common and more violent, according to a new study of volcanos in Chile’s Patagonia region, reports the Smithsonian magazine.

Since the start of the century, the world’s glaciers have lost some 5% of their collective mass. That is equivalent to about 8,500 gigatonnes, (8.5 quadrillion kilograms, or 8.5 x 10¹⁵ kg) based on United Nations’ Intergovernmental Panel on Climate Change (IPCC) estimates of glacier mass.

That is the same as a third of all the water in Lake Baikal, the biggest lake in the world, twice the volume of Lake Michigan and 95 times that of Lake Geneva. That amount of ice is very heavy indeed. So heavy that it puts enough pressure on volcanos to prevent them erupting. Now the ice is gone, that snowy cap on volcanos is disappearing too.

Scientists from the University of Wisconsin-Madison, Dickinson College and the University of La Frontera presented their findings on July 8 at the Goldschmidt Conference on geochemistry in Prague. The study shows that as glacial ice melts, the immense weight it once exerted on tectonic plates is reduced, which in turn decreases the pressure on magma chambers beneath the Earth’s surface and makes eruptions more likely.

“When you take the load off, it’s just like opening a Coca-Cola bottle or a champagne bottle,” said Brad Singer, geoscientist at the University of Wisconsin-Madison, in comments to Inside Climate News. “It’s under pressure, and the dissolved gasses in the melt come out as bubbles.”

The team focused its research on six volcanoes in Chile’s Patagonia region, including Mocho-Choshuenco, using argon dating and crystal analysis. During the last Ice Age, between 26,000 and 18,000 years ago, glaciers in the area formed a reservoir of magma ten miles underground. As the ice sheet retreated, pressure was released, and the compound stratovolcano system took shape.

“Glaciers tend to suppress the volume of eruptions from the volcanoes beneath them. But as glaciers retreat due to climate change, our findings suggest these volcanoes go on to erupt more frequently and more explosively,” said Pablo Moreno Yaeger, a graduate student at the University of Wisconsin-Madison who presented the research.

The study draws parallels with Iceland, where volcanic eruptions increased up to 50-fold after the last Ice Age. Scientists warn that similar dynamics may now be unfolding in other glaciated volcanic regions.

All eyes are now on Antarctica, where over 100 active volcanoes lie beneath the West Antarctic Ice Sheet. A 2023 study in Nature Climate Change predicted that this ice sheet is on track to melt significantly by the end of the century, even under aggressive emission reductions. A surge in volcanic activity could release heat and greenhouse gases, further accelerating ice loss and contributing to a global feedback loop.

The researchers note that the implications extend far beyond the Southern Hemisphere. A 2020 paper in Global and Planetary Change found that 245 active volcanoes worldwide are within five kilometres of ice. Further research published in Communications Earth & Environment last November indicated that glaciers near volcanoes are retreating 46% faster on average than those located farther away.

“Other continental regions, like parts of North America, New Zealand and Russia, also now warrant closer scientific attention,” Yaeger said.

A key method of forming planets finally has observational evidence, thanks to a network of radio telescopes in the U.K. that have resolved the existence of a huge abundance of centimeter-sized pebbles that will stick together and grow into planets around two young stars.

“This is potentially enough to build planetary systems larger than our own solar system,” said Katie Hesterly of the Square Kilometer Array (SKA) Observatory, the headquarters of which is based at Jodrell Bank radio observatory in the U.K., in a statement.