Connect with us

Published

on

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.


From smartphones with rollable displays or liquid cooling, to compact AR glasses and handsets that can be repaired easily by their owners, we discuss the best devices we’ve seen at MWC 2023 on Orbital, the Gadgets 360 podcast. Orbital is available on Spotify, Gaana, JioSaavn, Google Podcasts, Apple Podcasts, Amazon Music and wherever you get your podcasts.
Affiliate links may be automatically generated – see our ethics statement for details.

Continue Reading

Science

NASA Data Empowers Global Response to Rising Sea Levels

Published

on

By

NASA Data Empowers Global Response to Rising Sea Levels

Coastal communities around the world are confronting the realities of rising sea levels, which threaten both daily life and essential infrastructure. In response, NASA has collaborated with agencies such as the US Department of Defense, the World Bank, and the United Nations to deliver detailed data on global sea level rise. This information, accessible through NASA’s Earth Information Center, is intended to aid in the preparation and planning for coastal impacts expected through the year 2150.

As per a report by NASA, the centre offers projections of future sea levels and potential regional flooding over the next 30 years. The report highlights that this resource combines data from NASA’s ongoing satellite monitoring with computer modelling of ice sheet dynamics and ocean behaviour, alongside assessments from global authorities like the Intergovernmental Panel on Climate Change. These tools are designed to equip communities with accurate data on which they can base crucial coastal infrastructure and climate resilience plans.

Global Applications of NASA’s Data

Global institutions are using NASA’s sea level data to shape policies and implement adaptive strategies in vulnerable regions, the report mentioned. The World Bank, for example, integrates this information into Climate Risk Profiles for countries most susceptible to rising sea levels. Similarly, the U.S. Department of Defense leverages the data to foresee and mitigate the impacts on its coastal facilities, while the U.S. Department of State uses the information in disaster preparedness and adaptation planning for its international allies, the report further adds.

Selwin Hart, Assistant Secretary-General and special adviser to the United Nations on climate action, described the data as “a critical resource for protecting lives and livelihoods,” emphasising the disparity in impacts between a global warming limit of 1.5 degrees Celsius and current policy projections. This data, he noted, underscores the urgent need for action in vulnerable coastal areas.

Accelerating Rise of Global Sea Levels

The current rate of sea level rise has been shown to increase significantly, with nearly all coastal countries observing heightened sea levels from 1970 to 2023. According to Ben Hamlington, head of NASA’s sea level change team, the rise in sea levels is occurring at an accelerated pace, with average increases nearly doubling over the past three decades. Notably, NASA’s projections indicate that Pacific Island nations will see at least a 15-centimetre rise by 2050, accompanied by a marked increase in high-tide flooding.

The new data platform, as explained by Nadya Vinogradova Shiffer, director of NASA’s ocean physics programme, allows communities worldwide to anticipate future flooding scenarios.

Continue Reading

Science

Ancient pebbles in Israel hint at the earliest form of wheel technology

Published

on

By

Ancient pebbles in Israel hint at the earliest form of wheel technology

Archaeologists in Israel have uncovered doughnut-shaped pebbles that may be among the earliest forms of wheel-like technology. Found at the Nahal Ein Gev II site in northern Israel, these 12,000-year-old limestone pebbles feature central holes and are thought to have been used as spindle whorls—a tool for spinning fibres like flax and wool.

Talia Yashuv, a graduate student and co-author of the study at the Hebrew University of Jerusalem’s Institute of Archaeology, told LiveScience that these ancient artefacts suggest early experimentation with rotational tools that could have laid the foundation for later advancements like the potter’s wheel and the cart wheel. This discovery was published in PLOS One on November 13, offering a glimpse into pre-agricultural technology in the region.

The roughly 100 perforated pebbles were analysed by Yashuv and Leore Grosman, a professor of prehistoric archaeology at the same institute. After scanning each pebble in 3D, the team produced detailed models to assess their potential uses. Most of the pebbles were thought unlikely to serve as fishing weights or beads due to their size and shape, which diverge from artefacts used in similar periods. Instead, the team recreated spindle whorls from the scanned models, which traditional craft expert Yonit Crystal used to spin flax and wool. While the flax was easier to handle, the replicas demonstrated that the pebbles were likely effective as spindle whorls, supporting early textile production, the study noted.

Implications of the Findings

The findings indicate that these spindle whorls could mark a key point in technological evolution, potentially linked to new methods of storage and survival. Alex Joffe, a director at the Association for the Study of the Middle East and Africa and experienced archaeologist, told LiveScience that the possibility that these artefacts could have enabled innovations like bags or fishing lines. Yorke Rowan, an archaeology professor at the University of Chicago, echoed this view, noting that the analysis represents a “critical turning point” in early technology.

A Continuing Debate

While these pebbles may represent one of the earliest uses of wheel-like forms, Carole Cheval, an expert in prehistoric textiles at CEPAM in France, told that the publication that she observed that similar objects have been found in other regions, possibly from earlier periods. This adds another layer to understanding the origins of rotational technology, highlighting the ongoing exploration of ancient human innovation.

Continue Reading

Science

Binar satellites re-enter early due to high solar activity

Published

on

By

Binar satellites re-enter early due to high solar activity

An increase in solar activity has resulted in the early re-entry of three CubeSats from Curtin University’s Binar Space Program. These small satellites, which operated at low Earth orbit, were designed to last for at least six months. However, due to intensified solar conditions, they were destroyed within two months, significantly shortening their scientific mission.

CubeSats like Binar-2, 3 and 4 are particularly vulnerable to space weather impacts because they lack propulsion systems that could counteract the heightened atmospheric drag caused by solar activity. The satellite programme had launched Binar-1 in 2021 during relatively low solar activity, which allowed it to complete a full year in orbit.

The Science Behind Solar Activity

As per a report by The Conversation, solar activity, which includes phenomena such as solar flares, sunspots and solar wind, follows an 11-year cycle driven by the Sun’s magnetic field. Known as “solar cycle 25,” this phase has shown unexpected activity levels, currently over 1.5 times higher than projected. This has impacted not only the Binar satellites but also large-scale operations like the Starlink constellation and the International Space Station, both of which require continuous adjustments to counter increased drag.

Impact of Space Weather on Satellites and Earth

Increased solar activity generates higher levels of ionising radiation and charged particles. This can damage sensitive satellite electronics, disrupt radio communications and increase radiation exposure for astronauts. The intensified solar conditions have also expanded the Earth’s atmosphere outward, leading to increased drag for satellites in low Earth orbit. This affects many smaller satellites, which lack the capability to adjust their altitude.

The recent solar activity has also created more visible auroras, with these atmospheric light displays appearing closer to the equator than seen in decades.

Future Considerations for Space Missions

Despite current challenges, solar activity is expected to decline gradually, reaching a minimum by 2030. This pause may offer more favourable conditions for future missions. In response to current conditions, work has commenced on future Binar missions, which may benefit from a more predictable space weather environment.

Continue Reading

Trending