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Trump’s push to control Greenland echoes US purchase of Alaska from Russia in 1867

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theconversation.com – William L. Iggiagruk Hensley, Visiting Distinguished Professor, University of Alaska Anchorage – 2025-01-08 16:06:00

The U.S. bought Alaska and its significant natural resources and beautiful scenery for what amounts to a steal.

AP Photo/Mark Thiessen

William L. Iggiagruk Hensley, University of Alaska Anchorage

President-elect Donald Trump is again signaling his interest in Greenland through a series of provocative statements in which he’s mused about the prospect of the U.S. taking ownership – perhaps by force or economic coersion – of the world’s largest island by area.

Talk of a takeover of Greenland may seem fanciful. But it wouldn’t be the first time the U.S. was able to procure a piece of the Arctic. The U.S. bought Alaska from Russia in 1867. To mark the 150th anniversary of the sale in 2017, we asked William L. Iggiagruk Hensley, a visiting professor at the University of Alaska Anchorage, to write about that historic sale. This is the article we published then, with minor updates.

On March 30, 1867, U.S. Secretary of State William H. Seward and Russian envoy Baron Edouard de Stoeckl signed the Treaty of Cession. With a stroke of a pen, Tsar Alexander II had ceded Alaska, his country’s last remaining foothold in North America, to the United States for US$7.2 million.

That sum, amounting to just $138 million in today’s dollars, brought to an end Russia’s 125-year odyssey in Alaska and its expansion across the treacherous Bering Sea, which at one point extended the Russian Empire as far south as Fort Ross, California, 90 miles from San Francisco Bay.

Today, Alaska is one of the richest U.S. states thanks to its abundance of natural resources, such as petroleum, gold and fish, as well as its vast expanse of pristine wilderness and strategic location as a window on Russia and gateway to the Arctic.

So, what prompted Russia to withdraw from its American beachhead? And how did it come to possess it in the first place?

As a descendant of Inupiaq Eskimos, I have been living and studying this history all my life. In a way, there are two histories of how Alaska came to be American – and two perspectives. One concerns how the Russians took “possession” of Alaska and eventually ceded it to the U.S. The other is from the perspective of my people, who have lived in Alaska for thousands of years, and for whom the anniversary of the cession brings mixed emotions, including immense loss but also optimism.

Russia looks east

The lust for new lands that brought Russia to Alaska and eventually California began in the 16th century, when the country was a fraction of its current size.

That began to change in 1581, when Russia overran a Siberian territory known as the Khanate of Sibir, which was controlled by a grandson of Genghis Khan. This key victory opened up Siberia, and within 60 years the Russians were at the Pacific.

The Russian advance across Siberia was fueled in part by the lucrative fur trade, a desire to expand the Russian Orthodox Christian faith to the “heathen” populations in the east and the addition of new taxpayers and resources to the empire.

In the early 18th century, Peter the Great – who created Russia’s first navy – wanted to know how far the Asian landmass extended to the east. The Siberian city of Okhotsk became the staging point for two explorations he ordered. And in 1741, Vitus Bering successfully crossed the strait that bears his name and sighted Mt. Saint Elias, near what is now the village of Yakutat, Alaska.

Although Bering’s second Kamchatka expedition brought disaster for him personally when adverse weather on the return journey led to a shipwreck on one of the westernmost Aleutian Islands and his eventual death from scurvy in December 1741, it was an incredible success for Russia. The surviving crew fixed the ship, stocked it full of hundreds of the sea otters, foxes and fur seals that were abundant there, and returned to Siberia, impressing Russian fur hunters with their valuable cargo. This prompted something akin to the Klondike gold rush 150 years later.

Challenges emerge

But maintaining these settlements wasn’t easy. Russians in Alaska, who numbered no more than 800 at their peak, faced the reality of being half a globe away from Saint Petersburg, then the capital of the empire, making communications a key problem.

Also, Alaska was too far north to allow for significant agriculture and therefore unfavorable as a place to send large numbers of settlers. So they began exploring lands farther south, at first looking only for people to trade with so they could import the foods that wouldn’t grow in Alaska’s harsh climate. They sent ships to what is now California, established trade relations with the Spaniards there and eventually set up their own settlement at Fort Ross in 1812.

Thirty years later, however, the entity set up to handle Russia’s American explorations failed and sold what remained. Not long after, the Russians began to seriously question whether they could continue their Alaskan colony as well.

For starters, the colony was no longer profitable after the sea otter population was decimated. Then there was the fact that Alaska was difficult to defend, and Russia was short on cash due to the costs of the war in Crimea.

Americans eager for a deal

So, clearly, the Russians were ready to sell, but what motivated the Americans to want to buy?

In the 1840s, the United States had expanded its interests to Oregon, annexed Texas, fought a war with Mexico and acquired California. Afterward, Secretary of State Seward wrote in March 1848:

“Our population is destined to roll resistless waves to the ice barriers of the north, and to encounter oriental civilization on the shores of the Pacific.”

Almost 20 years after expressing his thoughts about expansion into the Arctic, Seward accomplished his goal.

In Alaska, the Americans foresaw a potential for gold, fur and fisheries, as well as more trade with China and Japan. The Americans worried that England might try to establish a presence in the territory, and the acquisition of Alaska, it was believed, would help the U.S. become a Pacific power. And overall the government was in an expansionist mode backed by the then-popular idea of “manifest destiny.”

So a deal with incalculable geopolitical consequences was struck, and the Americans seemed to get quite a bargain for their $7.2 million.

Just in terms of wealth, the U.S. gained about 370 million acres of mostly pristine wilderness, including 220 million acres of what are now federal parks and wildlife refuges. Hundreds of billions of dollars in whale oil, fur, copper, gold, timber, fish, platinum, zinc, lead and petroleum have been produced in Alaska over the years – allowing the state to do without a sales or income tax and give every resident an annual stipend. Alaska still likely has billions of barrels of oil reserves.

The state is also a key part of the United States defense system, with military bases located in Anchorage and Fairbanks, and it is the country’s only connection to the Arctic, which ensures it has a seat at the table as melting glaciers allow the exploration of the region’s significant resources.

Impact on Alaska Natives

But there’s an alternate version of this history.

When Bering finally located Alaska in 1741, Alaska was home to about 100,000 people, including Inuit, Athabascan, Yupik, Unangan and Tlingit. There were 17,000 alone on the Aleutian Islands.

Despite the relatively small number of Russians who at any one time lived at one of their settlements – mostly on the Aleutians Islands, Kodiak, Kenai Peninsula and Sitka – they ruled over the Native populations in their areas with an iron hand, taking children of the leaders as hostages, destroying kayaks and other hunting equipment to control the men and showing extreme force when necessary.

The Russians brought with them weaponry such as firearms, swords, cannons and gunpowder, which helped them secure a foothold in Alaska along the southern coast. They used firepower, spies and secured forts to maintain security, and they selected Christianized local leaders to carry out their wishes. They also met resistance, however, such as from the Tlingits, who were capable warriors, ensuring their hold on territory was tenuous.

By the time of the cession, only 50,000 Indigenous people were estimated to be left, as well as 483 Russians and 1,421 Creoles (descendants of Russian men and Indigenous women).

On the Aleutian Islands alone, the Russians enslaved or killed thousands of Aleuts. Their population plummeted to 1,500 in the first 50 years of Russian occupation due to a combination of warfare, disease and enslavement.

When the Americans took over, the United States was still engaged in its Indian wars, so they looked at Alaska and its Indigenous inhabitants as potential adversaries. Alaska was made a military district by Gen. Ulysses S. Grant.

For their part, Alaska Natives claimed that they still had title to the territory as its original inhabitants and having not lost the land in war or ceded it to any country – including the U.S., which technically didn’t buy it from the Russians but bought the right to negotiate with the Indigenous populations. Still, Natives were denied U.S. citizenship until 1924, when the Indian Citizenship Act was passed.

During that time, Alaska Natives had no rights as citizens and could not vote, own property or file for mining claims. The Bureau of Indian Affairs, in conjunction with missionary societies, in the 1860s began a campaign to eradicate Indigenous languages, religion, art, music, dance, ceremonies and lifestyles.

It was only in 1936 that the Indian Reorganization Act authorized tribal governments to form, and only nine years later overt discrimination was outlawed by Alaska’s Anti-Discrimination Act of 1945. The law banned signs such as “No Natives Need Apply” and “No Dogs or Natives Allowed,” which were common at the time.

Statehood and a disclaimer

Eventually, however, the situation improved markedly for Natives.

Alaska finally became a state in 1959, when President Dwight D. Eisenhower signed the Alaska Statehood Act, allotting it 104 million acres of the territory. And in an unprecedented nod to the rights of Alaska’s Indigenous populations, the act contained a clause emphasizing that citizens of the new state were declining any right to land subject to Native title – which by itself was a very thorny topic because they claimed the entire territory.

A result of this clause was that in 1971 President Richard Nixon ceded 44 million acres of federal land, along with $1 billion, to Alaska’s Native populations, which numbered about 75,000 at the time. That came after a Land Claims Task Force that I chaired gave the state ideas about how to resolve the issue.

Today, Alaska has a population of 740,000, of which 120,000 are Natives.

As the United States celebrates the signing of the Treaty of Cession, we all – Alaskans, Natives and Americans of the lower 48 – should salute Secretary of State William H. Seward, the man who eventually brought democracy and the rule of law to Alaska.

This article was first published on March 29, 2017.The Conversation

William L. Iggiagruk Hensley, Visiting Distinguished Professor, University of Alaska Anchorage

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Perfect brownies baked at high altitude are possible thanks to Colorado’s home economics pioneer Inga Allison

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theconversation.com – Tobi Jacobi, Professor of English, Colorado State University – 2025-04-22 07:47:00

Students work in the high-altitude baking laboratory.
Archives and Special Collections, Colorado State University

Tobi Jacobi, Colorado State University and Caitlin Clark, Colorado State University

Many bakers working at high altitudes have carefully followed a standard recipe only to reach into the oven to find a sunken cake, flat cookies or dry muffins.

Experienced mountain bakers know they need a few tricks to achieve the same results as their fellow artisans working at sea level.

These tricks are more than family lore, however. They originated in the early 20th century thanks to research on high-altitude baking done by Inga Allison, then a professor at Colorado State University. It was Allison’s scientific prowess and experimentation that brought us the possibility of perfect high-altitude brownies and other baked goods.

A recipe for brownies at high altitude.
Inga Allison’s high-altitude brownie recipe.
Archives and Special Collections, Colorado State University

We are two current academics at CSU whose work has been touched by Allison’s legacy.

One of us – Caitlin Clark – still relies on Allison’s lessons a century later in her work as a food scientist in Colorado. The other – Tobi Jacobi – is a scholar of women’s rhetoric and community writing, and an enthusiastic home baker in the Rocky Mountains, who learned about Allison while conducting archival research on women’s work and leadership at CSU.

That research developed into “Knowing Her,” an exhibition Jacobi developed with Suzanne Faris, a CSU sculpture professor. The exhibit highlights dozens of women across 100 years of women’s work and leadership at CSU and will be on display through mid-August 2025 in the CSU Fort Collins campus Morgan Library.

A pioneer in home economics

Inga Allison is one of the fascinating and accomplished women who is part of the exhibit.

Allison was born in 1876 in Illinois and attended the University of Chicago, where she completed the prestigious “science course” work that heavily influenced her career trajectory. Her studies and research also set the stage for her belief that women’s education was more than preparation for domestic life.

In 1908, Allison was hired as a faculty member in home economics at Colorado Agricultural College, which is now CSU. She joined a group of faculty who were beginning to study the effects of altitude on baking and crop growth. The department was located inside Guggenheim Hall, a building that was constructed for home economics education but lacked lab equipment or serious research materials.

A sepia-toned photograph of Inga Allison, a white woman in dark clothes with her hair pulled back.
Inga Allison was a professor of home economics at Colorado Agricultural College, where she developed recipes that worked in high altitudes.
Archives and Special Collections, Colorado State University

Allison took both the land grant mission of the university with its focus on teaching, research and extension and her particular charge to prepare women for the future seriously. She urged her students to move beyond simple conceptions of home economics as mere preparation for domestic life. She wanted them to engage with the physical, biological and social sciences to understand the larger context for home economics work.

Such thinking, according to CSU historian James E. Hansen, pushed women college students in the early 20th century to expand the reach of home economics to include “extension and welfare work, dietetics, institutional management, laboratory research work, child development and teaching.”

News articles from the early 1900s track Allison giving lectures like “The Economic Side of Natural Living” to the Colorado Health Club and talks on domestic science to ladies clubs and at schools across Colorado. One of her talks in 1910 focused on the art of dishwashing.

Allison became the home economics department chair in 1910 and eventually dean. In this leadership role, she urged then-CSU President Charles Lory to fund lab materials for the home economics department. It took 19 years for this dream to come to fruition.

In the meantime, Allison collaborated with Lory, who gave her access to lab equipment in the physics department. She pieced together equipment to conduct research on the relationship between cooking foods in water and atmospheric pressure, but systematic control of heat, temperature and pressure was difficult to achieve.

She sought other ways to conduct high-altitude experiments and traveled across Colorado where she worked with students to test baking recipes in varied conditions, including at 11,797 feet in a shelter house on Fall River Road near Estes Park.

Early 1900s car traveling in the Rocky Mountains.
Inga Allison tested her high-altitude baking recipes at 11,797 feet at the shelter house on Fall River Road, near Estes Park, Colorado.
Archives and Special Collections, Colorado State University

But Allison realized that recipes baked at 5,000 feet in Fort Collins and Denver simply didn’t work in higher altitudes. Little advancement in baking methods occurred until 1927, when the first altitude baking lab in the nation was constructed at CSU thanks to Allison’s research. The results were tangible — and tasty — as public dissemination of altitude-specific baking practices began.

A 1932 bulletin on baking at altitude offers hundreds of formulas for success at heights ranging from 4,000 feet to over 11,000 feet. Its author, Marjorie Peterson, a home economics staff person at the Colorado Experiment Station, credits Allison for her constructive suggestions and support in the development of the booklet.

Science of high-altitude baking

As a senior food scientist in a mountain state, one of us – Caitlin Clark – advises bakers on how to adjust their recipes to compensate for altitude. Thanks to Allison’s research, bakers at high altitude today can anticipate how the lower air pressure will affect their recipes and compensate by making small adjustments.

The first thing you have to understand before heading into the kitchen is that the higher the altitude, the lower the air pressure. This lower pressure has chemical and physical effects on baking.

Air pressure is a force that pushes back on all of the molecules in a system and prevents them from venturing off into the environment. Heat plays the opposite role – it adds energy and pushes molecules to escape.

When water is boiled, molecules escape by turning into steam. The less air pressure is pushing back, the less energy is required to make this happen. That’s why water boils at lower temperatures at higher altitudes – around 200 degrees Fahrenheit in Denver compared with 212 F at sea level.

So, when baking is done at high altitude, steam is produced at a lower temperature and earlier in the baking time. Carbon dioxide produced by leavening agents also expands more rapidly in the thinner air. This causes high-altitude baked goods to rise too early, before their structure has fully set, leading to collapsed cakes and flat muffins. Finally, the rapid evaporation of water leads to over-concentration of sugars and fats in the recipe, which can cause pastries to have a gummy, undesirable texture.

Allison learned that high-altitude bakers could adjust to their environment by reducing the amount of sugar or increasing liquids to prevent over-concentration, and using less of leavening agents like baking soda or baking powder to prevent dough from rising too quickly.

Allison was one of many groundbreaking women in the early 20th century who actively supported higher education for women and advanced research in science, politics, humanities and education in Colorado.

Others included Grace Espy-Patton, a professor of English and sociology at CSU from 1885 to 1896 who founded an early feminist journal and was the first woman to register to vote in Fort Collins. Miriam Palmer was an aphid specialist and master illustrator whose work crafting hyper-realistic wax apples in the early 1900s allowed farmers to confirm rediscovery of the lost Colorado Orange apple, a fruit that has been successfully propagated in recent years.

In 1945, Allison retired as both an emerita professor and emerita dean at CSU. She immediately stepped into the role of student and took classes in Russian and biochemistry.

In the fall of 1958, CSU opened a new dormitory for women that was named Allison Hall in her honor.

“I had supposed that such a thing happened only to the very rich or the very dead,” Allison told reporters at the dedication ceremony.

Read more of our stories about Colorado.The Conversation

Tobi Jacobi, Professor of English, Colorado State University and Caitlin Clark, Senior Food Scientist at the CSU Spur Food Innovation Center, Colorado State University

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Why don’t humans have hair all over their bodies? A biologist explains our lack of fur

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theconversation.com – Maria Chikina, Assistant Professor of Computational and Systems Biology, University of Pittsburgh – 2025-04-21 07:33:00

Some mammals are super hairy, some are not.
Ed Jones/AFP via Getty Images

Maria Chikina, University of Pittsburgh

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com.


Why don’t humans have hair all over their bodies like other animals? – Murilo, age 5, Brazil


Have you ever wondered why you don’t have thick hair covering your whole body like a dog, cat or gorilla does?

Humans aren’t the only mammals with sparse hair. Elephants, rhinos and naked mole rats also have very little hair. It’s true for some marine mammals, such as whales and dolphins, too.

Scientists think the earliest mammals, which lived at the time of the dinosaurs, were quite hairy. But over hundreds of millions of years, a small handful of mammals, including humans, evolved to have less hair. What’s the advantage of not growing your own fur coat?

I’m a biologist who studies the genes that control hairiness in mammals. Why humans and a small number of other mammals are relatively hairless is an interesting question. It all comes down to whether certain genes are turned on or off.

Hair benefits

Hair and fur have many important jobs. They keep animals warm, protect their skin from the sun and injuries and help them blend into their surroundings.

They even assist animals in sensing their environment. Ever felt a tickle when something almost touches you? That’s your hair helping you detect things nearby.

Humans do have hair all over their bodies, but it is generally sparser and finer than that of our hairier relatives. A notable exception is the hair on our heads, which likely serves to protect the scalp from the sun. In human adults, the thicker hair that develops under the arms and between the legs likely reduces skin friction and aids in cooling by dispersing sweat.

So hair can be pretty beneficial. There must have been a strong evolutionary reason for people to lose so much of it.

Why humans lost their hair

The story begins about 7 million years ago, when humans and chimpanzees took different evolutionary paths. Although scientists can’t be sure why humans became less hairy, we have some strong theories that involve sweat.

Humans have far more sweat glands than chimps and other mammals do. Sweating keeps you cool. As sweat evaporates from your skin, heat energy is carried away from your body. This cooling system was likely crucial for early human ancestors, who lived in the hot African savanna.

Of course, there are plenty of mammals living in hot climates right now that are covered with fur. Early humans were able to hunt those kinds of animals by tiring them out over long chases in the heat – a strategy known as persistence hunting.

Humans didn’t need to be faster than the animals they hunted. They just needed to keep going until their prey got too hot and tired to flee. Being able to sweat a lot, without a thick coat of hair, made this endurance possible.

Genes that control hairiness

To better understand hairiness in mammals, my research team compared the genetic information of 62 different mammals, from humans to armadillos to dogs and squirrels. By lining up the DNA of all these different species, we were able to zero in on the genes linked to keeping or losing body hair.

Among the many discoveries we made, we learned humans still carry all the genes needed for a full coat of hair – they are just muted or switched off.

In the story of “Beauty and the Beast,” the Beast is covered in thick fur, which might seem like pure fantasy. But in real life some rare conditions can cause people to grow a lot of hair all over their bodies. This condition, called hypertrichosis, is very unusual and has been called “werewolf syndrome” because of how people who have it look.

A detailed painting of a man and a woman standing next to one another in historical looking clothes. The man's face is covered in hair, while the woman's is not.
Petrus Gonsalvus and his wife, Catherine, painted by Joris Hoefnagel, circa 1575.
National Gallery of Art

In the 1500s, a Spanish man named Petrus Gonsalvus was born with hypertrichosis. As a child he was sent in an iron cage like an animal to Henry II of France as a gift. It wasn’t long before the king realized Petrus was like any other person and could be educated. In time, he married a lady, forming the inspiration for the “Beauty and the Beast” story.

While you will probably never meet someone with this rare trait, it shows how genes can lead to unique and surprising changes in hair growth.


Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.The Conversation

Maria Chikina, Assistant Professor of Computational and Systems Biology, University of Pittsburgh

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Scientists found a potential sign of life on a distant planet – an astronomer explains why many are still skeptical

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theconversation.com – Daniel Apai, Associate Dean for Research and Professor of Astronomy and Planetary Sciences, University of Arizona – 2025-04-18 17:44:00

An illustration of the exoplanet K2-18b, which some research suggests may be covered by deep oceans.
NASA, ESA, CSA, Joseph Olmsted (STScI)

Daniel Apai, University of Arizona

A team of astronomers announced on April 16, 2025, that in the process of studying a planet around another star, they had found evidence for an unexpected atmospheric gas. On Earth, that gas – called dimethyl sulfide – is mostly produced by living organisms.

In April 2024, the James Webb Space Telescope stared at the host star of the planet K2-18b for nearly six hours. During that time, the orbiting planet passed in front of the star. Starlight filtered through its atmosphere, carrying the fingerprints of atmospheric molecules to the telescope.

A diagram showing planets and stars emitting light, which goes through JWST detectors, where it's split into different wavelengths to make a spectrum. Each spectrum suggests the presence of a different element.
JWST’s cameras can detect molecules in the atmosphere of a planet by looking at light that passed through that atmosphere.
European Space Agency

By comparing those fingerprints to 20 different molecules that they would potentially expect to observe in the atmosphere, the astronomers concluded that the most probable match was a gas that, on Earth, is a good indicator of life.

I am an astronomer and astrobiologist who studies planets around other stars and their atmospheres. In my work, I try to understand which nearby planets may be suitable for life.

K2-18b, a mysterious world

To understand what this discovery means, let’s start with the bizarre world it was found in. The planet’s name is K2-18b, meaning it is the first planet in the 18th planetary system found by the extended NASA Kepler mission, K2. Astronomers assign the “b” label to the first planet in the system, not “a,” to avoid possible confusion with the star.

K2-18b is a little over 120 light-years from Earth – on a galactic scale, this world is practically in our backyard.

Although astronomers know very little about K2-18b, we do know that it is very unlike Earth. To start, it is about eight times more massive than Earth, and it has a volume that’s about 18 times larger. This means that it’s only about half as dense as Earth. In other words, it must have a lot of water, which isn’t very dense, or a very big atmosphere, which is even less dense.

Astronomers think that this world could either be a smaller version of our solar system’s ice giant Neptune, called a mini-Neptune, or perhaps a rocky planet with no water but a massive hydrogen atmosphere, called a gas dwarf.

Another option, as University of Cambridge astronomer Nikku Madhusudhan recently proposed, is that the planet is a “hycean world”.

That term means hydrogen-over-ocean, since astronomers predict that hycean worlds are planets with global oceans many times deeper than Earth’s oceans, and without any continents. These oceans are covered by massive hydrogen atmospheres that are thousands of miles high.

Astronomers do not know yet for certain that hycean worlds exist, but models for what those would look like match the limited data JWST and other telescopes have collected on K2-18b.

This is where the story becomes exciting. Mini-Neptunes and gas dwarfs are unlikely to be hospitable for life, because they probably don’t have liquid water, and their interior surfaces have enormous pressures. But a hycean planet would have a large and likely temperate ocean. So could the oceans of hycean worlds be habitable – or even inhabited?

Detecting DMS

In 2023, Madhusudhan and his colleagues used the James Webb Space Telescope’s short-wavelength infrared camera to inspect starlight that filtered through K2-18b’s atmosphere for the first time.

They found evidence for the presence of two simple carbon-bearing molecules – carbon monoxide and methane – and showed that the planet’s upper atmosphere lacked water vapor. This atmospheric composition supported, but did not prove, the idea that K2-18b could be a hycean world. In a hycean world, water would be trapped in the deeper and warmer atmosphere, closer to the oceans than the upper atmosphere probed by JWST observations.

Intriguingly, the data also showed an additional, very weak signal. The team found that this weak signal matched a gas called dimethyl sulfide, or DMS. On Earth, DMS is produced in large quantities by marine algae. It has very few, if any, nonbiological sources.

This signal made the initial detection exciting: on a planet that may have a massive ocean, there is likely a gas that is, on Earth, emitted by biological organisms.

An illustration of what scientists imagine K2-18b to look like, which looks a little like Earth, with clouds and a translucent surface.
K2-18b could have a deep ocean spanning the planet, and a hydrogen atmosphere.
Amanda Smith, Nikku Madhusudhan (University of Cambridge), CC BY-SA

Scientists had a mixed response to this initial announcement. While the findings were exciting, some astronomers pointed out that the DMS signal seen was weak and that the hycean nature of K2-18b is very uncertain.

To address these concerns, Mashusudhan’s team turned JWST back to K2-18b a year later. This time, they used another camera on JWST that looks for another range of wavelengths of light. The new results – announced on April 16, 2025 – supported their initial findings.

These new data show a stronger – but still relatively weak – signal that the team attributes to DMS or a very similar molecule. The fact that the DMS signal showed up on another camera during another set of observations made the interpretation of DMS in the atmosphere stronger.

Madhusudhan’s team also presented a very detailed analysis of the uncertainties in the data and interpretation. In real-life measurements, there are always some uncertainties. They found that these uncertainties are unlikely to account for the signal in the data, further supporting the DMS interpretation. As an astronomer, I find that analysis exciting.

Is life out there?

Does this mean that scientists have found life on another world? Perhaps – but we still cannot be sure.

First, does K2-18b really have an ocean deep beneath its thick atmosphere? Astronomers should test this.

Second, is the signal seen in two cameras two years apart really from dimethyl sulfide? Scientists will need more sensitive measurements and more observations of the planet’s atmosphere to be sure.

Third, if it is indeed DMS, does this mean that there is life? This may be the most difficult question to answer. Life itself is not detectable with existing technology. Astronomers will need to evaluate and exclude all other potential options to build their confidence in this possibility.

The new measurements may lead researchers toward a historic discovery. However, important uncertainties remain. Astrobiologists will need a much deeper understanding of K2-18b and similar worlds before they can be confident in the presence of DMS and its interpretation as a signature of life.

Scientists around the world are already scrutinizing the published study and will work on new tests of the findings, since independent verification is at the heart of science.

Moving forward, K2-18b is going to be an important target for JWST, the world’s most sensitive telescope. JWST may soon observe other potential hycean worlds to see if the signal appears in the atmospheres of those planets, too.

With more data, these tentative conclusions may not stand the test of time. But for now, just the prospect that astronomers may have detected gasses emitted by an alien ecosystem that bubbled up in a dark, blue-hued alien ocean is an incredibly fascinating possibility.

Regardless of the true nature of K2-18b, the new results show how using the JWST to survey other worlds for clues of alien life will guarantee that the next years will be thrilling for astrobiologists.The Conversation

Daniel Apai, Associate Dean for Research and Professor of Astronomy and Planetary Sciences, University of Arizona

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