Category: 7. Science

In a new image sent from Mars, NASA’s Curiosity rover has captured something that immediately caught scientists’ attention– a small, oddly shaped rock that closely resembles coral. According to a report by NASA, the image was taken on July 24, 2025, during the rover’s 4,609th day on the Martian surface.At first glance, it may seem like a curious shape. But behind this formation lies a much older and more detailed story– one that stretches back billions of years to a time when Mars was a very different place.Ancient water and wind: The forces that shaped itAccording to the NASA report, this type of structure is the result of a common geological process. In the distant past, when liquid water still existed on Mars, it seeped into cracks in rocks. That water carried dissolved minerals, which settled into the cracks and stayed behind once the water dried up.Over time, the surrounding rock, which was less resistant, was worn away by continuous wind erosion– leaving the mineral deposits exposed in unusual shapes. These formations, while shaped by natural forces, are often visually complex and have been compared to floral or marine structures found on Earth, as per the NASA report.Close-up Captured by ChemCamAccording to the report, the image of the coral-like rock was taken using the Remote Micro Imager (RMI), a component of the ChemCam instrument aboard Curiosity. ChemCam plays a key role in helping scientists study the composition and texture of rocks from a distance.Around the same period, another rock with a similar form was observed using Curiosity’s Mars Hand Lens Imager, adding more detail to this ongoing study of Martian geology.According to the NASA report, the ChemCam itself is the result of an international partnership– developed by the U.S. Department of Energy’s Los Alamos National Laboratory, in collaboration with the French space agency CNES, the University of Toulouse, and CNRS.A mission that keeps deliveringCuriosity, which landed on Mars in 2012, continues to operate from NASA’s Jet Propulsion Laboratory in California. The rover is part of NASA’s Mars Science Laboratory project and operates under the broader Mars Exploration Program, led by the agency’s Science Mission Directorate in Washington.Not just an odd shapeWhile the rock’s shape has drawn interest due to its resemblance to coral, the real significance lies in what it tells us about Mars. Formations like these offer evidence that water once played an active role in shaping the Martian surface.Wind, minerals, and erosion have combined over billions of years to create the landscapes that Curiosity continues to explore today. This latest find is another reminder of how much Mars has changed– and how much there is still to understand.Thumb image: X/@astrobiobuzz

For over two decades, scientists have been puzzled by this genetic anomaly. Three major populations of white sharks show striking variation in mitochondrial DNA, despite nearly identical nuclear DNA. Early on, migration patterns seemed to explain the mismatch. But new research, published in Proceedings of the National Academy of Sciences, has upended that theory.

Origins After the Ice Age
The mystery traces back to the end of the last Ice Age, about 10,000 years ago. Back then, lower sea levels confined white sharks to a single Indo-Pacific population. As the climate warmed, sharks dispersed to new regions, and by roughly 7,000 years ago, they had split into three genetically distinct groups.

Today, those populations live in the southern hemisphere near Australia and South Africa, the northern Atlantic, and the northern Pacific. But their total global population is tiny—around 20,000 individuals, according to study co-author Gavin Naylor of the Florida Museum of Natural History. “There are more fruit flies in any given city than there are great white sharks in the entire world,” he noted.

An Unexpected Discovery
In 2001, researchers studying sharks from Australia, New Zealand, and South Africa found something odd: nuclear DNA was almost identical across all samples, but mitochondrial DNA in South African sharks differed significantly from that in Australian and New Zealand sharks.

The prevailing explanation was female philopatry—the tendency of females to return to the same place to breed—paired with wide-ranging male migrations. This could keep nuclear DNA uniform (thanks to roaming males) while allowing mitochondrial DNA to diverge (since it’s passed down from females).

Theory Overturned
The new study revisited the question with updated DNA analyses, directly testing the philopatry theory. The results were clear: migration patterns could not account for the mitochondrial differences.

That leaves only one possible explanation—natural selection. But here’s the twist: for natural selection to be responsible, given the sharks’ small population sizes, it would need to be “brutally lethal,” Naylor said. In other words, any deviation from the dominant mitochondrial DNA sequence would have to be fatal, preventing it from being passed on.

Case Still Open
The researchers stress that natural selection is not yet a confirmed answer. Genetic drift is ruled out, migration is off the table, and the selection hypothesis still needs strong evidence. For now, the genetic divide in white sharks remains an open case—one of the ocean’s most enduring scientific mysteries.

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The landing marks a successful end to their mission on board the International Space Station to help stranded pilots.

Four astronauts have returned to Earth after hurrying to the International Space Station (ISS) five months ago to relieve stranded test pilots of Boeing’s Starliner.

Their SpaceX capsule parachuted into the Pacific off the Southern California coast on Saturday, a day after departing the orbiting lab.

“Welcome home,” SpaceX Mission Control radioed.

Splashing down were NASA’s Anne McClain and Nichole Ayers, Japan’s Takuya Onishi and Russia’s Kirill Peskov. They launched in March as replacements for the two NASA astronauts assigned to Starliner’s botched demo.

Starliner malfunctions kept Butch Wilmore and Suni Williams at the space station for more than nine months instead of a week.

NASA ordered Boeing’s new crew capsule to return empty and switched the pair to SpaceX. They left soon after McClain and her crew arrived to take their places. Wilmore has since retired from NASA.

Before leaving the space station on Friday, McClain made note of “some tumultuous times on Earth”, with people struggling.

“We want this mission, our mission, to be a reminder of what people can do when we work together, when we explore together,” she said.

McClain looked forward to “doing nothing for a couple of days” once back home in Houston. High on her crewmates’ wish list: Hot showers and juicy burgers.

It was SpaceX’s third Pacific splashdown with people on board, but the first for a NASA crew in 50 years. Tech billionaire Elon Musk’s company switched capsule returns from Florida to California’s coast earlier this year to reduce the risk of debris falling on populated areas. Back-to-back private crews were the first to experience Pacific homecomings.

The last time NASA astronauts returned to the Pacific from space was during the 1975 Apollo-Soyuz mission, a historic detente meet-up of Americans and Soviets in orbit during the Cold War years.

Loreto Caceres/Penguin Random House

Loreto Caceres/Penguin Random House

There are an endless stream of high-tech gadgets that promise to ease parenting fears and make the experience of child rearing more enjoyable. But at what cost? Does constant monitoring through pregnancy and early childhood make anyone safer… or happier? Today on The Sunday Story, we bring you an episode from our colleagues at On The Media. It’s a conversation with author Amanda Hess about her new book, “Second Life: Having A Child In The Digital Age.”

For handpicked podcast recommendations every week, subscribe to NPR’s Pod Club newsletter at npr.org/podclub.

This episode of The Sunday Story was produced by Andrew Mambo. It was edited by Jenny Schmidt.

The original On The Media episode was produced by Molly Rosen, edited by Katya Rogers and engineered by Jared Paul.

We’d love to hear from you. Send us an email at TheSundayStory@npr.org.

Hollywood star Tom Hanks has paid a moving tribute to American astronaut James Lovell, the real-life space hero he portrayed in the 1995 classic ‘Apollo 13’. Lovell passed away on Thursday at the age of 97 in Lake Forest, Illinois.

Hanks, who won an Oscar for ‘Forrest Gump’ and starred as Lovell in the space drama, took to Instagram on Friday to share heartfelt words about the man whose courage and leadership inspired millions.

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“There are people who dare, who dream, and who lead others to places we wouldn’t go on our own,” Hanks wrote. “Jim Lovell was that kind of guy. For a long time, he had gone farther into space and for longer than anyone else on Earth. His journeys were not for money or fame, but because challenges like those are what make life worth living.”

Tom Hanks on James Lovell:

Lovell’s NASA career began long before private space travel became a playground for tech billionaires. In 1968, he was part of the historic Apollo 8 mission, the first manned spacecraft to orbit the moon. But his most famous mission came two years later with Apollo 13.

What was meant to be a smooth lunar landing turned into a fight for survival when an oxygen tank exploded mid-journey. As commander, Lovell’s quick thinking and calm leadership helped his crew navigate a near-freezing lunar module all the way back to Earth.

Also Read: Kelley Mack, known for ‘The Walking Dead’, dies at 33 after battle with cancer

The mission was famously described as “a successful failure” because, although they didn’t land on the moon, all three astronauts returned safely.

In his tribute, Hanks noted that Lovell’s passing coincided with a full moon, adding: “On this night of a full Moon, he passes on to the heavens, to the cosmos, to the stars. God speed you, on this next voyage, Jim Lovell.”

Lovell’s heroism earned him the Congressional Space Medal of Honor in 1995, presented by then-President Bill Clinton. That same year, before ‘Apollo 13’ began filming, Lovell invited Hanks to his home.

In a true astronaut fashion, he even let the actor fly his airplane at night so Hanks could better understand the feeling of being a pilot in the dark skies.

Scientists noticed an odd occurrence on august 5. The Earth’s rotation was slower than usual on this particular day. The day grew somewhat longer as a result. Ordinary people, however, did not understand this distinction. However, this occurrence has been characterized as significant by scientists. According to them, this incident may provide crucial details regarding the forces influencing the Earth’s rotation. The Earth revolves around the sun and rotates on its axis.

What happened to Earth’s speed on august 5?

The Earth’s revolution that day lasted roughly 86,400.00145 seconds, according to scientists, which is 1.45 milliseconds longer than usual. There is not much of a shift in the Earth’s rotation speed. This is why precise measurements utilizing atomic clocks and astronomical observations were able to detect it.

What is a solar day?
A solar day lasts 86,400 seconds, or 24 hours.  Natural variations in wind patterns, sea currents, and processes in the Earth’s interior cause minor changes in this.  In addition, the primary cause of the Earth’s rotation slowing down is the Moon’s tidal attraction.

What was out of the ordinary this time?
According to scientists, atmospheric conditions in the Southern Hemisphere were a contributing factor in the august 5 drop in Earth’s rotation speed.  The Earth’s surface saw a one-minute pause in certain places due to stronger-than-normal winds, which extended the day by milliseconds.

What impact did this have on Earth’s rotation, and why is it important?

This was also influenced by sea currents that were impacted by the Moon’s gravity.  Scientists say that such a phenomenon occurs when the tidal pull is a little stronger.  The speed of rotation is also impacted by activity in the Earth’s molten outer core.  According to scientists, extremely precise systems like satellite communications and GPS navigation can be impacted by even a slight variation in the Earth’s rotation of less than a millisecond.  Numerous time-related computations may go awry if this occurs.