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Some of the water around Antarctica has been getting saltier. And that has affected the amount of sea ice at the bottom of the planet.

A study published on June 30 in the Proceedings of the National Academy of Sciences found that increases in salinity in seawater near the surface could help explain some of the decrease in Antarctic sea ice that have been observed over the past decade, reversing a previous period of growth.

“The impact of Antarctic ice is massive in terms of sea-level rise, in terms of global warming, and therefore, in terms of extremes,” said Alessandro Silvano, a senior scientist at the University of Southampton studying the Southern Ocean and lead author of the study. The findings mean “we are entering a new system, a new world”, he said.

Each year, the sea ice floating atop the Earth’s polar oceans melts in the summer and refreezes in the winter, acting as a mirror that bounces the sun’s heat back into space. Since the late 1970s, as global temperatures ratcheted upward, sea ice in the Arctic has been swiftly declining. But in the Antarctic sea ice continued to grow into the 2010s.

The study used data from satellites to track changes by using a brightness measurement that subtly correlates to salt content. But because the signal is small and easily drowned out by other factors, Dr Silvano said, it wasn’t possible to analyse them effectively until recent advances in algorithms.

When Dr Silvano and his co-authors first noticed the rising salinity, they doubted the signal was real, suspecting an error in the satellite data. But as physical measurements from ocean instruments began to confirm the trend, they realised the signal was accurate.

“Because melting ice should freshen the ocean, we thought that we should have seen freshening, right?” Dr Silvano said, adding that climate change is also increasing precipitation and runoff from melting glaciers in the Antarctic, which should mean more fresh water coming into the ocean’s surface. “Instead, we saw increasing salinity.”

As the salt content increases, the density of the water changes, drawing warmer water – typically stashed deep under the surface – upward. Hotter water causes the ice floating on it to melt, and prevents it from growing back in the winter as much as it used to.

Because less sea ice means less fresh water balancing out the salinity and warmth, it’s a feedback loop that threatens greater warming, he said.

Sharon Stammerjohn, a senior research associate at the University of Colorado Boulder’s Institute of Arctic and Alpine Research, who was not involved in the research, described the paper as a sort of missing link for the potential drivers of Antarctic sea-ice changes.

“We have been struggling for about the last decade to try to figure out why Antarctic sea ice had such a rapid decline and continues to decline,” she said.

Typically, Dr Stammerjohn said, the ocean acts as a bank of planetary heat. Because fresher water is less dense, it acts as a lid, holding back the salt and trapping heat deep below the surface. Rising salinity means the layers of the ocean are mixing more, and letting more heat escape to the surface. “Up until 2015 we kind of kept a lid on that,” she said.

Cecilia Bitz, a professor of climate science at the University of Washington, said observations of the Antarctic’s complex dynamics and vast, hard-to-access landscape remained sparse until about 10 years ago. Then, improvements in satellite data along with a growing fleet of autonomous buoys with sensors, known as Argo floats, which provided some of the data used in Dr Silvano’s study, began to fill in the gaps.

Recently, the Department of Defense announced it would be no longer be providing some of the satellite data that researchers use to monitor changes in sea ice. According to an announcement Monday, the data will become unavailable after July 31.

“This not only affects polar researchers who rely on this for Antarctic sea ice and Arctic sea ice, but another sensor on there is key for hurricane forecasting,” Dr Stammerjohn said.

While the details of how the scientific community might adapt when this program is canceled are unclear, she said, there are other satellite products, including ones maintained by the European Space Agency and the Japan Aerospace Exploration Agency, that may be able to fill the gap. NYTIMES

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The Vera C. Rubin Observatory has revealed its first imagery, which will be followed by more detailed observations to gain a deeper understanding of the universe

Located at the top of Cerro Pachón in Chile, the observatory is a joint venture by the U.S. National Science Foundation (NSF) and the Department of Energy (DOE), designed to transform our understanding of the cosmos.

In just over ten hours of early test observations, the observatory has already captured millions of stars and galaxies, along with thousands of asteroids.

A next-generation eye on the sky

Rubin Observatory stands out as one of the most advanced optical astronomical facilities ever built. Its 8.4-meter telescope features the largest digital camera in the world, paired with an advanced data processing system capable of handling a massive volume of astronomical information.

Set to begin its full scientific operations in 2025, the observatory’s main project, the Legacy Survey of Space and Time (LSST), will scan the entire visible Southern Hemisphere sky every few nights for ten years. This effort will produce a dynamic, high-resolution time-lapse view of the night sky, unlike anything seen before.

The universe’s most profound mysteries

A key goal of the Rubin Observatory is to help scientists investigate some of the biggest unanswered questions in cosmology. These include the nature of dark matter and dark energy, mysterious forces that together comprise approximately 95% of the universe but remain poorly understood.

The observatory’s detailed and frequent observations will provide important data to improve scientific models of how galaxies form and evolve, as well as how the universe is expanding and whether previously unknown cosmic phenomena exist.

Improving planetary defence

The Rubin Observatory will also revolutionise our understanding of the solar system. Its nightly sky scans will detect millions of asteroids, comets, and even interstellar objects, many of which have never been observed before.

This capability makes Rubin the most powerful solar system discovery tool ever constructed. Its findings will be vital for planetary defence efforts, potentially identifying space rocks that pose a future threat to Earth or the moon.

Creating a stream of data

The observatory’s data output is expected to surpass the combined total of all previous optical observatories, just in its first year of operation. Over its decade-long mission, Rubin will produce an archive of information,
The imagery and insights generated will be publicly accessible, enabling collaboration not only among professional scientists but also among citizen scientists and educators worldwide.

Named in honour of astronomer Vera C. Rubin, who provided the first compelling evidence for dark matter, the observatory is set to create a new era of astronomical discovery.

China’s Tianwen-2 probe has officially begun its deep space mission by capturing a stunning image of Earth and the Moon from 590,000 kilometers away. Released by the China National Space Administration (CNSA) on July 1, the image symbolises the start of a decade-long journey to explore a near-Earth asteroid and a distant comet. Launched on May 29, Tianwen-2 will collect samples from asteroid Kamo’oalewa by 2027 and later investigate comet 311P/PANSTARRS. This dual-target mission marks a significant step forward for China’s space program, aiming to unlock key secrets about the origin of the Moon, water, and life.

Tianwen-2 probe: Earth-Moon images from deep space released by CNSA

The stunning photo was taken on May 30, 2025, when Tianwen-2 was nearly 590,000 kilometers away from Earth. The picture beautifully frames Earth and its natural satellite, the Moon, together in the vast darkness of space. This image was captured using the spacecraft’s narrow-field-of-view navigation sensor, an instrument designed to help the spacecraft maintain its orientation and enable precise autonomous navigation.This camera plays a critical role in guiding Tianwen-2 through deep space, allowing it to operate independently from ground control while maintaining stability during its long voyage.

Tianwen-2 marks milestone with over 12 million km travelled since May 29 launch

As of July 1, 2025, CNSA reports that Tianwen-2 is operating smoothly. As reported, the Tianwen-2 probe has been in orbit for 33 days with a distance of 12 million kilometres since its May 29 launch from the Xichang Satellite Launch Center aboard a Long March 3B rocket. Its successful performance in this early stage builds confidence in its ability to complete its complex multi-target mission.This probe is part of China’s broader space strategy to expand its scientific reach beyond the Moon and Mars, pushing boundaries into asteroid and comet exploration—domains previously dominated by NASA, ESA, and JAXA.

Tianwen-2 heads toward Kamo’oalewa; a mysterious near-Earth asteroid

Tianwen-2 is heading toward Kamo’oalewa, a small near-Earth asteroid that orbits the Sun in a path similar to Earth’s. What makes this asteroid particularly intriguing is the hypothesis that it might be a fragment of the Moon, dislodged by a massive impact event in the distant past.Upon arrival in 2026, the spacecraft will conduct detailed investigations, including:

The samples will then be returned to Earth by 2027, providing researchers with rare, untouched material from a near-Earth object—potentially from the Moon’s ancient past.

Tianwen-2 to explore mysterious comet after asteroid sample return

Tianwen-2’s mission doesn’t end after the asteroid sample returns. It will be re-tasked to study the comet 311P/PANSTARRS, known for its active tail and mysterious dust ejection events. This phase of the mission could begin shortly after the asteroid visit and will involve:

Scientists hope this exploration could provide vital clues about the origin of Earth’s water and organic molecules, helping to answer one of science’s oldest questions—how life-supporting ingredients arrived on our planet.

Tianwen-2 sets a new standard with 10-year asteroid-to-comet space voyage

According to The Astronomy Magazine, the Tianwen-2 mission is planned to last more than 10 years, making it one of the longest and most scientifically rich deep-space missions in China’s history. Its dual-phase nature—first targeting an asteroid, then a comet—requires exceptional engineering and mission planning.This strategy mirrors the complexity and ambition of missions like NASA’s OSIRIS-REx and ESA’s Rosetta, but with a uniquely Chinese twist: combining asteroid sample return and comet observation into a single, seamless voyage.Also Read | NASA alert! 120-foot airplane-sized asteroid 2025 MM to make closest flyby on Earth today; should we be concerned