When astronomers search for evidence of life beyond Earth, what signs are they seeking?
Would clues be traced to microfossils trapped within ancient Martian rocks, swim in waters of an ocean world or lead to an Earth-like twin thought of as Planet B? Or perhaps a technosignature, a signal that could be created by intelligent life, might point scientists in the right direction.
The scientific community has debated the question — as well as where the evidence of life may be found — for years.
This week, researchers shared a finding from an intriguing exoplanet that might represent the next step toward discovering whether life is possible on another world.
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Using the James Webb Space Telescope, astronomers have found chemical fingerprints in the atmosphere of the distant planet K2-18b that could belong to molecules only created by life on Earth.
The molecules, dimethyl sulfide and potentially dimethyl disulfide, are typically made by marine phytoplankton on Earth.
Nikku Madhusudhan, professor of astrophysics and exoplanetary science at the University of Cambridge’s Institute of Astronomy, and his colleagues believe K2-18b, located 124 light-years from Earth, is a Hycean world, or a potentially habitable planet entirely covered in liquid water with a hydrogen-rich atmosphere, as seen in the illustration above.
“Given everything we know about this planet, a Hycean world with an ocean that is teeming with life is the scenario that best fits the data we have,” he said.
However, the study authors have not declared a definitive discovery of life beyond our planet — and experts remain skeptical about the idea of the molecules representing signs of biological activity.
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An expedition seeking previously unknown marine life has revealed the first footage of a colossal squid, which resembles a “glass sculpture,” in its native deep-sea environment. |
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This week, six female passengers, including singer Katy Perry and journalist Gayle King, went on a roughly 10-minute journey to space and back again aboard a Blue Origin New Shepard flight. But how exactly do experts define where Earth ends and space begins during such a brief jaunt?
The capsule reached 346,802 feet (106 kilometers) above ground level and 350,449 feet above mean sea level (107 kilometers). New Shepard traveled well above the Kármán line, a point at 62 miles (100 kilometers) that’s often used to define the altitude at which airspace ends and outer space begins.
But throughout the history of its usage, the Kármán line has often been controversial.
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Seismologist Deborah Kilb was the first to notice unusual tremors beneath the Sierra Nevada. They were occurring at a depth where Earth’s crust is typically too hot for quake activity, said Kilb of the Scripps Institution of Oceanography at the University of California, San Diego.
Now, Kilb and other researchers studying deep rock deformations beneath the Sierra Nevada have used an imaging technique to map Earth’s internal structure — and they detected the planet’s crust peeling away.
The phenomenon could shed light on how the continents formed and determine whether there are other parts of the planet where the crust is peeling.
Separately, the contents of a 4.6 billion-year-old rare type of meteorite could change how scientists understand Earth’s origin story and just how long water has been present on the planet.
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Amateur astronomers discovered a new comet, known as C/2025 F2 (SWAN), at the end of March, but in recent days, the celestial object’s story has gained a new twist.
The latest observations of the comet suggest the object, made of ancient rock, frozen gases and dust, has disintegrated on its way to a close approach of the sun, which was anticipated to occur on May 1.
However, the comet’s remnant is still visible and will be for a few weeks, according to experts. Here’s everything you need to know about how and when to see it.
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As the weather warms up, the great outdoors beckons with possibilities — but not if you’re a magnet for mosquitoes. Our partners at CNN Underscored, a product reviews and recommendations guide owned by CNN, suggest the Bug Bite Thing. The simple tool is designed to relieve itching and swelling by extracting an insect’s saliva or venom immediately following a bug bite.
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NASA astronaut Don Pettit has ventured to space four times, and the veteran scientist is due to return to Earth on Saturday from his most recent stint aboard the International Space Station.
In addition to inventing the Zero-G coffee cup that allows astronauts to enjoy a hot beverage as they would on Earth, Pettit is also known for his stunning photography (above) of the cosmos.
To celebrate his homecoming, here are some of Pettit’s awe-inspiring images from his seven-month stay on the orbiting laboratory, including long-exposure views of the colors that dance above Earth.
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