Category: 7. Science

SpaceX launched a fresh batch of Starlink spacecraft into orbit this morning (Sep. 3), lofting 28 more satellites into the company’s megaconstellation of over 8,000.

A Falcon 9 rocket lifted off from Space Launch Complex-40, at Cape Canaveral Space Force Station in Florida at 7:56 a.m. EDT (1156 GMT). It came just over 8 hours after a different Falcon 9 launched 24 Starlink satellites of its own late Monday night from SpaceX’s Vandenberg Space Force Base pad in California.

The Sun is the most energetic particle accelerator in the Solar System. It whips up electrons to nearly the speed of light and flings them out into space, flooding the Solar System with so-called ‘Solar Energetic Electrons’ (SEEs).

Researchers have now used Solar Orbiter to pinpoint the source of these energetic electrons and trace what we see out in space back to what’s actually happening on the Sun. In a paper to be published in Astronomy & Astrophysics on September 1, they explain that they found two kinds of SEE with clearly distinct stories: one connected to intense solar flares (explosions from smaller patches of the Sun’s surface), and one to larger eruptions of hot gas from the Sun’s atmosphere (known as ‘coronal mass ejections’, or CMEs).

“We see a clear split between ‘impulsive’ particle events, where these energetic electrons speed off the Sun’s surface in bursts via solar flares, and ‘gradual’ ones associated with more extended CMEs, which release a broader swell of particles over longer periods of time,” says lead author Alexander Warmuth of the Leibniz Institute for Astrophysics Potsdam (AIP), Germany.

A clearer connection

While scientists were aware that two types of SEE event existed, Solar Orbiter was able to measure a large number of events, and look far closer to the Sun than other missions had, to reveal how they form and leave the surface of our star.

“We were only able to identify and understand these two groups by observing hundreds of events at different distances from the Sun with multiple instruments – something that only Solar Orbiter can do,” adds Alexander. “By going so close to our star, we could measure the particles in a ‘pristine’ early state and thus accurately determine the time and place they started at the Sun.”

Flight delays

The researchers detected the SEE events at different distances from the Sun. This let them study how the electrons behave as they travel through the Solar System, answering a lingering question about these energetic particles.

When we spot a flare or a CME, there’s often an apparent lag between what we see taking place at the Sun, and the release of energetic electrons into space. In extreme cases, the particles seem to take hours to escape. Why?

“It turns out that this is at least partly related to how the electrons travel through space – it could be a lag in release, but also a lag in detection,” says co-author and ESA Research Fellow Laura Rodríguez-García. “The electrons encounter turbulence, get scattered in different directions, and so on, so we don’t spot them immediately. These effects build up as you move further from the Sun.”

The space between the Sun and the planets of the Solar System isn’t empty. A wind of charged particles streams out from the Sun constantly, dragging the Sun’s magnetic field with it. It fills space and influences how the energetic electrons travel; rather than being able to go where they like, they are confined, scattered, and disturbed by this wind and its magnetism.

The study fulfils an important goal of Solar Orbiter: to continuously monitor our star and its surroundings to trace ejected particles back to their sources at the Sun.

“Thanks to Solar Orbiter, we’re getting to know our star better than ever,” says Daniel Müller, ESA Project Scientist for Solar Orbiter. “During its first five years in space, Solar Orbiter has observed a wealth of Solar Energetic Electron events. As a result, we’ve been able to perform detailed analyses and assemble a unique database for the worldwide community to explore.”

Keeping Earth safe

Crucially, the finding is important for our understanding of space weather, where accurate forecasting is essential to keep our spacecraft operational and safe. One of the two kinds of SEE events is more important for space weather: that connected to CMEs, which tend to hold more high-energy particles and so threaten far more damage. Because of this, being able to distinguish between the two types of energetic electrons is hugely relevant for our forecasting.

“Knowledge such as this from Solar Orbiter will help protect other spacecraft in the future, by letting us better understand the energetic particles from the Sun that threaten our astronauts and satellites,” adds Daniel. “The research is a really great example of the power of collaboration – it was only possible due to the combined expertise and teamwork of European scientists, instrument teams from across ESA Member States, and colleagues from the US.”

Looking ahead, ESA’s Vigil mission will pioneer a revolutionary approach, operationally observing the ‘side’ of the Sun for the first time, unlocking continuous insights into solar activity. To be launched in 2031, Vigil will detect potentially hazardous solar events before they come into view as seen from Earth, giving us advance knowledge of their speed, direction and chance of impact.

Our understanding of how our planet responds to solar storms will also be investigated further with the launch of ESA’s Smile mission next year. Smile will study how Earth endures the relentless ‘wind’, and sporadic bursts, of fierce particles thrown our way from the Sun, exploring how the particles interact with our planet’s protective magnetic field.

Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA.

All of this suggests that life might be common on planets that support liquid water, but it might be uncommon to find life that studies the universe and seeks to travel through space, like we do. To find extraterrestrial life, it might be necessary for us to travel to it.

However, the vastness of space, coupled with the impossibility of traveling or communicating faster than the speed of light, places practical limits on how far we can roam. Only the closest stars to the sun could possibly be visited in a human lifetime, even by a space probe. In addition, only stars similar in size and temperature to the sun are long-lived enough, and have stable enough atmospheres, for multicellular life to have time to form. For this reason, the most valuable stars to study are the 60 or so sun-like stars that are closer to us than approximately 30 light-years. The most promising planets orbiting these stars would have sizes and temperatures similar to the Earth, so solid ground and liquid water can exist.

A needle in the haystack

Observing an Earth-like exoplanet separately from the star it is orbiting around is a major challenge. Even in the best possible scenario, the star is a million times brighter than the planet; if the two objects are blurred together, there is no hope of detecting the planet. Optics theory says that the best resolution one can get in telescope images depends on the size of the telescope and the wavelength of the observed light. Planets with liquid water give off the most light at wavelengths around 10 microns (the width of a thin human hair and 20 times the typical wavelength of visible light). At this wavelength, a telescope needs to collect light over a distance of at least 20 meters to have enough resolution to separate the Earth from the sun at a distance of 30 light-years. Additionally, the telescope must be in space, because looking through the Earth’s atmosphere would blur the image too much. However, our largest space telescope – the James Webb Space Telescope (JWST) – is only 6.5 meters in diameter, and that telescope was extremely difficult to launch.

Because deploying a 20-meter space telescope seems out-of-reach with current technology, scientists have explored several alternative approaches. One involves launching multiple, smaller telescopes that maintain extremely accurate distances between them, so that the whole set acts as one telescope with a large diameter. But, maintaining the required spacecraft position accuracy (which must be precisely calibrated to the size of a typical molecule) is also currently infeasible.

Other proposals use shorter wavelength light, so that a smaller telescope can be used. However, in visible light a sun-like star is more than 10 billion times brighter than the Earth. It is beyond our current capability to block out enough starlight to be able to see the planet in this case, even if in principle the image has high enough resolution.

One idea for blocking the starlight involves flying a spacecraft called a ‘starshade’ that is tens of meters across, at a distance of tens of thousands of miles in front of the space telescope, so that it exactly blocks the light from the star while the light from a companion planet is not blocked. However, this plan requires that two spacecraft be launched (a telescope and a starshade). Furthermore, pointing the telescope at different stars would entail moving the starshade thousands of miles, using up prohibitively large quantities of fuel.

A rectangular perspective

In our paper, we propose a more feasible alternative. We show that it is possible to find nearby, Earth-like planets orbiting sun-like stars with a telescope that is about the same size as JWST, operating at roughly the same infrared (10 micron) wavelength as JWST, with a mirror that is a one by 20 meter rectangle instead of a circle 6.5 meters in diameter.

With a mirror of this shape and size, we can separate a star from an exoplanet in the direction that the telescope mirror is 20 meters long. To find exoplanets at any position around a star, the mirror can be rotated so its long axis will sometimes align with the star and planet. We show that this design can in principle find half of all existing Earth-like planets orbiting sun-like stars within 30 light-years in less than three years. While our design will need further engineering and optimization before its capabilities are assured, there are no obvious requirements that need intense technological development, as is the case for other leading ideas.

If there is about one Earth-like planet orbiting the average sun-like star, then we would find around 30 promising planets. Follow-up study of these planets could identify those with atmospheres that suggest the presence of life, for example oxygen that was formed through photosynthesis. For the most promising candidate, we could dispatch a probe that would eventually beam back images of the planet’s surface. The rectangular telescope could provide a straightforward path towards identifying our sister planet: Earth 2.0.

Scientists found AMORE6, a galaxy almost free of heavy elements. Its existence strongly supports key predictions of the Big Bang model.

Our knowledge of the Universe begins with the Big Bang, the moment when cosmic expansion first began. During this event, a process called Big Bang nucleosynthesis produced only the lightest elements: hydrogen, helium, and trace amounts of lithium. Heavier elements, which astrophysicists refer to as metals, were created later in the hearts of stars that lived and died after this first epoch.

The earliest generation of stars, known as Population III stars, were the first to forge these heavier elements through stellar nucleosynthesis. These stars themselves contained no metals, or at most extremely small amounts, and their life cycles enriched the Universe with its first metals. Because stars are born in galaxies rather than in isolation, there must also have been Population III galaxies whose stellar populations contained no metals at all.

Despite progress in understanding cosmic history, significant gaps remain. One of the most important missing pieces is evidence for these Population III galaxies. Theory predicts that some early galaxies, observed at high redshifts, should display zero metallicity. Confirming their existence would provide crucial support for our current cosmological framework.

Surprising results from JWST

The James Webb Space Telescope (JWST) has already reshaped expectations by revealing massive, well-developed galaxies far earlier in cosmic history than models had predicted. According to previous understanding, galaxies of that size and maturity should not have appeared so soon after the Big Bang. These discoveries have forced astronomers to reconsider how quickly galaxies formed and evolved.

Yet, even with its remarkable capabilities, JWST has not definitively identified a zero-metallicity galaxy. While it has observed galaxies that emerged only a few hundred million years after the Big Bang, none of them have yet shown the complete absence of metals predicted for true Population III systems.

The role of OIII emissions

Oxygen plays an essential role in this search. According to cosmological models, the earliest galaxies should contain only hydrogen and helium, with no oxygen or other heavier elements. Astronomers use the OIII emission line in spectroscopy to study galaxies: it reveals ongoing star formation and is especially effective at probing very distant, high-redshift systems. JWST, with its sensitivity, has made these measurements even more powerful.

In primitive galaxies, strong OIII emissions can indicate very low metallicity. Conversely, weak OIII signals suggest galaxies formed under conditions unlike those seen today. Until recently, no convincing example had been found.

That may now be changing. New research submitted to Nature reports the possible discovery of a galaxy that fits the criteria for being pristine. The study is led by Takahiro Morishita, a staff scientist at the Infrared Processing and Analysis Center (IPAC) at the California Institute of Technology.

“The existence of galaxies with no elements such as Oxygen – formed by stars after Big Bang nucleosynthesis – is a key prediction of the cosmological model,” the researchers write. “However, no pristine “zero-metallicity” Population III galaxies have been identified so far.”

Confirming the Big Bang model

Until now. Morishita and his co-authors have found a galaxy that fits the description. They detected it at redshift z = 5.725, meaning its light was emitted when the Universe was only about 900 million to 1 billion years old. It’s named AMORE6 and was detected through gravitational lensing. This magnified and duplicated the images of the galaxy, making it easier to observe. The JWST found Hβ emissions, an important line in astronomy used to measure galaxies in different ways, but it didn’t detect any oxygen. That means its metallicity is very low. “The absence of [O iii] immediately indicates that AMORE6 harbors a very low-metallicity, near pristine, interstellar medium,” the authors explain.

The galaxy also shows low stellar-mass and an extremely compact morphology. “These properties are consistent with massive star formation in a pristine or near-pristine environment,” the authors write. The thing is, this galaxy isn’t as old as some earlier, fully-formed galaxies the JWST found. It’s somewhat puzzling that this strong example of a pristine and low-metallicity star-forming environment was found almost one billion years after the Big Bang.

More studies will be needed to confirm these findings and understand them in greater detail. But the detection suggests that we are on the right track in understanding Nature.

“The finding of such an example at a relatively late time in cosmic history is surprising,” the researchers write. “However, regardless of cosmic epoch, the identification of a potentially pristine object is a key validation of the Big Bang model.”

Reference: “Pristine Massive Star Formation Caught at the Break of Cosmic Dawn” by Takahiro Morishita, Zhaoran Liu, Massimo Stiavelli, Tommaso Treu, Pietro Bergamini and Yechi Zhang, 31 July 2025, arXiv.
DOI: 10.48550/arXiv.2507.10521

Adapted from an article originally published on Universe Today.

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In one of the most unusual natural discoveries of recent years, scientists have observed what they call “salt snow” falling beneath the surface of the Dead Sea. Unlike normal snowfall, this strange process happens underwater as halite crystals form and descend like snowflakes. Researchers believe this rare phenomenon may help explain how massive underground salt structures such as chimneys, domes, and kilometer-thick deposits are created. Triggered by climate change, evaporation, and water diversion, the “salt snow” not only reshapes the Dead Sea but also offers clues to Earth’s geological past.

What is ‘salt snow’ of Dead Sea

Salt snow refers to the precipitation of halite crystals within the Dead Sea. Normally, salt crystallization is seen in shallow or cold water layers, but here it occurs year-round, even during summer. The process begins when surface water becomes warmer and saltier due to evaporation. This dense water cools and sinks, while colder, less salty water from below rises. The mixing of these layers triggers crystal formation in mid-water zones, creating the illusion of snow falling underwater.

How the Dead Sea became a natural laboratory

The Dead Sea is the lowest point on Earth’s surface and one of the saltiest water bodies in the world, making it uniquely suited for such phenomena. Historically, its water remained layered and stable. But since the 1980s, reduced inflow from the Jordan River and intensified evaporation have disrupted this balance. As a result, annual mixing of water layers now fuels continuous salt crystallization. Unlike other seas such as the Red Sea or the Mediterranean, where similar processes ended millions of years ago, the Dead Sea remains active, offering a living glimpse into Earth’s geological history.

Salt giants beneath the surface

These falling crystals accumulate over time, forming vast salt structures beneath the seabed. Known as salt giants, chimneys, and domes, they can reach more than a kilometer in thickness and extend over vast distances. Such formations are crucial for geologists because they mirror conditions during the Messinian Salinity Crisis over 5 million years ago, when the Mediterranean dried up and massive salt deposits were left behind. The Dead Sea now serves as a smaller-scale model of that ancient process.

Climate change and its role

The salt snow is not just a scientific curiosity, it reflects wider environmental shifts. Climate change, combined with human-driven freshwater diversion, has caused the Dead Sea’s water level to drop by about one meter per year. This accelerates salinity increases and alters stratification, intensifying salt precipitation. The unusual “snowfall” thus acts as a visible marker of climate stress on fragile ecosystems, highlighting how human activities and warming temperatures reshape natural processes.

Why it matters globally

Understanding the Dead Sea’s salt snow provides more than local insights. These formations record climate fluctuations and hydrological imbalances, offering a geological archive of environmental change. On a broader scale, studying this phenomenon could shed light on how coastal systems respond to rising salinity and climate change worldwide. It also informs research into erosion, resource extraction, and the stability of other saltwater basins.

McGill University researchers have developed a novel method to replicate four types of microplastics commonly found in the environment, providing researchers with a standardized approach to study their toxic effects.

“We  regularly see news about microplastics in our bodies or the environment. While this news is scary, we have yet to fully comprehend their effects in these places,” said Audrey Moores, Professor in the Department of Chemistry and co-author of the paper, published in Environmental Science and Technology.

“We are still very far from any quantitative  understanding of what it means to have microplastics in all these places. Consequently, it’s really critical for public policy development that we develop a standardized platform for testing their toxicity,” Moores added.

McGill PhD Candidate Jasmine Hong is the paper’s lead author.  Subhasis Ghoshal, Professor of Civil Engineering, co-supervised the research.

The struggle to find – or make – uniform samples

Scientists have struggled to obtain or create standardized microplastic samples. Environmental collection is costly and complicated, often yielding a mix of plastic types. Makers of samples in the lab have been unable to control their size, roughness and surface chemistries precisely enough, factors that are crucial to understanding toxicity.

The researchers’ method addresses those gaps with nano-level precision. 

“Researchers have made microplastics in the lab, but we were still missing a method that would allow us to make specific sizes of microplastics with desired  surface chemistry and roughness. These parameters are critical because we know that they are key in determining the toxicity of nanomaterials,” Moores said.

Their approach also produces smaller microplastic samples than typically seen in lab settings, which Moores said is vital for toxicological analysis.

A three-step recipe for replication

The teams used a three-step approach to fabricate the microplastics. First, cryomilling, or grinding particles under cold temperatures, allowed them to control size and to make smaller particles. Second, they exposed the particles to UV light, which helped them control surface oxidation. Third, they used a chemical reaction to roughen the plastics’ surface.

The result is a clear, reproducible strategy for creating microplastics in the lab.

“We did a very in-depth analysis to really understand how to make the smallest copies, which are harder to make. Particle size is a key feature defining how microparticles can interact with organs. The smaller the particle, the more effects it can have,” Moores said. “This will allow us to test for toxicity in a much more standardized fashion to truly understand the effects of microplastics.”

PhD candidate Jasmine Hong is already working on next steps.

“I want to use these models to test how microplastics interact with other pollutants or toxic compounds,” she said.

About this study

“Accelerated Weathering of Microplastics: A Systematic Approach to Model Microplastic Production,” by Jasmine Hong, Olivia Hengelbrok, Julien Gigault, Subhasis Ghoshal and Audrey Moores, was published in Environmental Science and Technology.

The research was funded by the Natural Science and Engineering Research Council of Canada (NSERC), the NSERC-Collaborative Research and Training Experience in Sustainable Electronics and Eco-Design, the Canada Foundation for Innovation, the Fonds de recherche du Québec – Nature et technologies and the McGill Sustainability Systems Initiative.

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Today in the history of astronomy, Viking 2 touches down.

It may not be as dramatic as a total solar eclipse, but there’s something equally epic about watching Earth’s shadow gradually engulfing and coloring the moon during a total lunar eclipse. The next total lunar eclipse — colloquially called a “blood moon” — will occur on Sept. 7-8, 2025, but it won’t be another 177 days until the phenomenon is visible from parts of North America, on March 2-3, 2026.

An eclipse of the moon is a global event, happening at a specific time, and only those on the night side of Earth see it. On Sept. 7-8, North America won’t be on the night side, with prime visibility limited to Africa, India, China and Australia. Western Europe will get a glimpse of the event at moonrise, but mostly misses out on the event, too. That’s a shame because the Sept.7-8 total lunar eclipse will see the lunar surface turn reddish for 82 minutes, just as it did on March 13-14, 2025, when moongazers in North America were in prime position for some spectacular photos.