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Since time immemorial, humans around the world have gazed up in wonder at the night sky. The starry night sky has not only inspired countless works of music, art, and poetry but has also played an important role in timekeeping, navigation and agricultural practices in many traditions.

For many cultures, the night sky, with its stars, planets and the Milky Way, is considered just as important a part of the natural environment as the forests, lakes and mountains below. Countless people around the world gaze at the night sky: not only amateur and professional astronomers, but also casual observers who enjoy looking up at the stars to contemplate our place in the cosmos.

However, the night sky is changing. Not only is ground-based light pollution increasing rapidly, but growing numbers of satellites and space debris in orbit around Earth are also impacting the night sky.

Earlier research showed that satellites and space debris may increase the overall brightness of the night sky. In a new paper in Nature Astronomy, my colleagues and I applied this knowledge to predicting the performance of a major astronomical sky survey. We found this phenomenon may make the survey 7.5 percent less efficient and US$21.8 million (roughly Rs. 180 crore) more expensive.

A brighter sky

As a cultural astronomer, I am interested in the role of the night sky in cultural traditions around the world. In particular, I am interested in how light pollution and increasing satellite numbers affect different communities.

The number of satellites in orbit is growing rapidly. Since 2019, the number of functional satellites in orbit has more than doubled to around 7,600. The increase is mostly due to SpaceX and other companies launching large groups of satellites to provide high-speed internet communications around the world.

By the end of this decade, we estimate, there may be 100,000 satellites in orbit around the Earth. Collisions that generate space debris are more likely as space fills with new satellites. Other sources of debris include the intentional destruction of satellites in space warfare tests.

Increasing numbers of satellites and space debris reflect ever more sunlight towards the night side of Earth. This will almost certainly change the appearance of the night sky and make it harder for astronomers to do research.

One way satellites impact astronomy is by appearing as moving points of light, which show up as streaks across astronomers’ images. Another is by increasing diffuse night sky brightness. This means all the satellites that are too dim or small to be seen individually, as well as all the small bits of space debris, still reflect sunlight, and their collective effect is to make the night sky appear less dark.

Hard times for astronomers

In our research, we present the first published calculations of the aggregate effects of satellites and space debris in low-Earth orbit on major ground-based astronomy research facilities.

We looked at the effect on the planned large-scale survey of the night sky to be carried out at the Vera Rubin Observatory starting in 2024. We found that, by 2030, reflected light from objects in low-Earth orbit will likely increase the diffuse background brightness for this survey by at least 7.5 percent compared to an unpolluted sky.

This would diminish the efficiency of this survey by 7.5 percent as well. Over the ten-year lifetime of the survey, we estimate this would add some $21.8 million (roughly Rs. 180 crore) to the total project cost.

Brighter night skies mean longer exposures through telescopes are needed to see distant objects in the cosmos. This will mean that for projects with a fixed amount of observing time, less science will be accomplished, and there will be increased competition for telescope access.

In addition, brighter night skies will also reduce the detection limits of sky surveys, and dimmer objects may not be detected, resulting in missed research opportunities.

Some astrophysical events are rare and if researchers are unable to view them when they occur, there might not be an opportunity to easily see a given event again during a survey’s operational period. One example of faint objects is near-Earth objects – comets and asteroids in orbits close to Earth. Brighter night skies make it more likely such potentially hazardous objects may remain undetected.

A dramatic and unprecedented transformation

Increases in diffuse night sky brightness will also change how we see the night sky with the unaided eye. As the human eye cannot resolve individual small objects as well as a telescope can, an increase in satellites and space debris will create an even greater increase in the apparent brightness of the night sky. (When using a telescope or binoculars, one would be able to make out more of the dimmer satellites individually.) The projected increase in night sky brightness will make it increasingly difficult to see fainter stars and the Milky Way, both of which are important in various cultural traditions. Unlike “ground-based” light pollution (which tends to be the worst near large cities and heavily populated areas), the changes to the sky will be visible from essentially everywhere on Earth’s surface.

Our models give us a conservative lower limit for a likely increase in night sky brightness. If numbers of satellites and space debris continue to grow at the expected rate, the impacts will be even more pronounced.

As we note in our paper, “we are witnessing a dramatic, fundamental, and perhaps semi-permanent transformation of the night sky without historical precedent and with limited oversight”. Such a transformation will have profound consequences for professional astronomy as well as for anyone who wishes to view an unpolluted night sky.


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Did Domesticated Cats Originate in Tunisia? New Study Sheds Light

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Did Domesticated Cats Originate in Tunisia? New Study Sheds Light

The origin of domestic cats has been a prominent topic amongst researchers. Their emergence has been linked to the Neolithic period, where they accompanied the farmers while spreading across Europe, along with the agricultural adaptation. However, further investigations have been conducted wherein the significance puzzled the archaeologists. Recently, two large-scale investigations were conducted by the University of Rome Tor Vergata and 42 institutions, and another by the University of Exeter and contributors from 37 institutions, pointing out that Tunisia could be the place of the origin of the domestic cat.

The Tor Vergata Study on Cats

The expert team of researchers from the University of Rome Tor Vergata conducted paleo-genomic analyses, where they analyzed the specimens of cats from 97 archaeological sites across Europe and Anatolia. Likewise, they also took samples from North Africa, Bulgaria, and Italy.

According to the study published on bioRxiv titled “The dispersal of domestic cats from Northern Africa and their introduction to Europe over the last two millennia”, the researchers analysed a total of 70 low-coverage ancient genomes, 37 radiocarbon-dated cat remains, and 17 modern and museum genomes.

The Tor Vergata Study Results

The Tor Vergata Team, as a result of the nuclear DNA analyses, identified felines embedded by domestic ancestry that appeared from the first century CE onwards in Europe. The team also identified two introductory waves — one from the second century BCE, where wildcats were brought from Northwest Africa to Sardinia, raising the current island population, whereas the other wave belonged to the Roman Imperial period, where the cats genetically sounded similar to domestic cats in Europe. Here, Tunisia was observed as the base for early domestication.

The University of Exeter Study

According to a reprint titled, “Redefining the timing and circumstances of cat domestication, their dispersal trajectories, and the extirpation of European Wildcats,” the collaborative study by the University of Exeter shed light on a distinct timeline. They analysed 2,416 archeological field bones around 206 sites and cross-referenced morphological data, accompanied by genetic findings.

The key findings of this collaborative study defined that domestic cats first appeared in the early first millennium BCE in Europe. Their existence occurred before Roman expansion.

The Egyptian Connection

According to mythological theories, the emergence of domestication of cats was related to religious and cultural dimensions. In Egypt, the cats were considered holy. Also, in Greek culture, these creatures became religious symbols of Artemis and Diana — a multifaceted divinity.

Although the two studies offer different understandings, the results indicate that cats appeared in Europe after moving from North Africa as a result of cultural practices, religious reverence, and trade networks.

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Ocean of Magma Might Be Flowing Underneath the Earth’s Surface

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Ocean of Magma Might Be Flowing Underneath the Earth’s Surface

A new study published on March 26 in the Nature journal revealed that the magma ocean formation near Earth’s core started around 4.4 billion years ago. It might be impacting the Earth today as odd mantle anomalies. Discoveries suggest that Earth inevitably sheltered a deep basal magma believed to have existed at the boundary between the mantle and core. This helped the scientists explain the baffling structure of the mantle, such as the Large Low-Velocity (LLVPS) discovered with the help of seismic imaging. This event has played a crucial role in Earth’s shape with thermal and tectonic evolution.

Discovery and Implications

Assistant Professor Charles-Édouard Boukaré of York University, Toronto, who led this study, told Live Science that these magma oceans could affect thermal communication between the mantle and core, further affecting the tectonic plates’ location.

A new model proposed by his team combines geochemical and seismic data to help researchers explore how early crystallisation could lead to the persistent molten layer formed deep inside the planet. Boukaré, James Badro, and Henri Samuel are affiliated with the French Research Institutions and played a major role in the study published in the Nature journal.

Formation of Basal Magma Ocean

The team discovered that the magma ocean formation is inevitable, irrespective of the direction of Earth’s mantle solidification, either from core to surface or vice versa. In each case, the new Earth model proposes that dense iron oxide-rich solids sank near the Earth’s core and remelted (iron has a low melting point) due to the high temperature and pressure conditions, causing a permanent ocean of magma. Boukaré emphasised that a basal melt would be formed despite the least conducive scenarios.

Lasting Effects and Geological Memory

This study shows that the deep magma ocean left a lasting imprint on the interior of Earth around a few hundred million years ago. In a statement given to the publication, Boukaré said that there is a memory, explaining that Earth’s internal structure was shaped very early in the past and still plays a significant role in bringing geological processes such as tectonic movement and mantle convection. Dating back around 4.4 billion years, LLVPS may be the remnants of this ancient primordial layer.

Looking to Other Planets

Boukaré is seeking to expand the model with further trace elements and practice it on other planets made of rocks. He said that maybe this basal magma ocean event is not so unique to the Earth. This research could open new doors into comprehending the planetary formation across the solar system.

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Exoplanet Found Orbiting Binary Stars on a Sideways Path

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Exoplanet Found Orbiting Binary Stars on a Sideways Path

Researchers have found an odd Milky Way planet orbiting over and under the poles of two failing stars. Star systems arise from flattened, spinning disks of gas and dust, with materials gathering along the plane of the disk, forming planets, moons, and asteroids around a newborn star. Only sixteen exoplanets had ever been verified to circle a binary pair; all of those planets orbit in the plane of the stars’ orbits of one another, not over the poles. The elusiveness of these planets makes this find very fascinating.

Researchers knew of the two objects this odd planet orbits before they came upon it. They originally identified the do-si-doing pair using the SPECULOOS Southern Observatory in Chile in 2018, only to find they were brown dwarfs, failed stars insufficient in mass to ignite. The system began to look stranger once they zoomed in on the binary pair with the Very Large Telescope at the Paranal Observatory in Chile.

Scientists Find First Polar Planet in Bizarre Double-Brown-Dwarf System

According to the report, scientists have found the strangest planetary system yet observed, featuring the first-ever “polar planet” and a planet that orbits two stars. Better known as “failed stars,” brown dwarfs—stellar bodies that fail to gather enough materials to attain the mass required to start the fusion of hydrogen to helium in their cores—are the parent stellar bodies of exoplanet 2M1510 (AB). This discovery is the first solid evidence of such a fully formed system.

Exoplanet 2 M1510 (AB) b is a stellar body known as a “failed star” because it fails to gather enough matter to reach the mass needed to start the fusion of hydrogen to helium in its core. The chance of stellar bodies having a binary partner increases with mass, making a double-brown-dwarf star system pretty surprising.

Rare Eclipsing Brown Dwarf Pair Hosts First Known Polar-Orbit Planet

This is only the second pair of eclipsing brown dwarfs ever discovered, meaning one of the brown dwarfs eclipses the other, as seen from Earth’s vantage point. Team member Amaury Triaud of the University of Birmingham said that “a planet orbiting not just a binary, but a binary brown dwarf, as well as being on a polar orbit, is rather incredible and exciting.”

The discovery was incidental, since the observations were not aimed at such a planet or orbital arrangement. This realization usually helps one to understand what is sensible on the interesting planet we live on.

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