Billions of years ago, Earth was an uninhabitable rock covered in magma. Scientists are still working to decipher the tale of how it transformed into a blue and green orb teeming with life.
However, each year, as science continues to advance, we learn more about our planet’s mysterious history. In 2025, scientists lifted the curtain on strange phenomena, revealed the age of the oldest known rock formation, uncovered a thriving ecosystem nearly 6 miles beneath the ocean surface and detected unexpected movement in the planet’s core.
Here are some of the ways scientific research shaped our understanding of planet Earth in 2025.
A rocky outcrop in a remote corner of northern Quebec harbors the oldest known surviving fragments of Earth’s crust, according to a June study. The discovery opens the door for further examination of the rock formation and any fossils it contains to illuminate an unknown chapter in Earth’s history.
The exposed remnant of the ancient ocean floor, called the Nuvvuagittuq outcrops, dates to 4.16 billion years ago, making it the only rock determined to be from the first of four geological eons in our planet’s history: the Hadean.
This eon began 4.6 billion years ago when the world was thought to be hot, turbulent and hell-like, but scientists say it’s possible that the newly dated rock formation may preserve signatures of life from the Hadean.
However, it’s not yet clear whether the Nuvvuagittuq outcrops will become widely accepted as Earth’s oldest rocks — a long-running scientific debate.
The rock sample didn’t contain a tough mineral known as a zircon — the easiest and most reliable way to date old rock formations — and little is definitive when dealing with rocks and minerals that have histories spanning more than 4 billion years.
‘Microlightning,’ will-o’-the-wisps and the origins of life
Will-o’-the-wisps, the eerie glowing light spotted over bogs, swamps and marshes through the centuries, have inspired folklore, ghost stories and even a quirky 1980s UK cartoon.
But the cause of the flickering phenomenon has never been clear. Theories have included static electricity, swarming insects, birds carrying glowing fungus or lightning that ignites swamp gas.
The last hypothesis was not far from the mark, according to researchers who have revealed a scientific explanation. Their study, published in September, indicated that tiny flashes of lightning ignite microscopic bubbles of methane.
However, the “microlightning” doesn’t come from the sky. It instead originates from electrically charged bubbles of water that interact with methane to produce the flashes of light.
Another study, published in March, found that microlightning in primordial mist may have sparked the chemical formation of the building blocks of life more than 3 billion years ago.
Unlike the geographic North Pole, which marks a fixed location where all the lines of longitude that curve around Earth converge, the magnetic north pole’s position is determined by Earth’s magnetic field, which is in constant motion.
Over the past few decades, magnetic north’s movement dramatically sped up before rapidly slowing from 2015. Scientists can’t explain the underlying cause behind the magnetic field’s unusual behavior.
In 2025, scientists updated the World Magnetic Model — which helps preserve the accuracy of global positioning systems such as those used by planes and ships — by resetting the official position of magnetic north and introducing new predictions for its movement over the next five years.
Since its discovery in 1831, magnetic north has drifted away from Canada and toward Russia, sometimes quickly, sometimes slowly.
In 1990, its movement accelerated, increasing from 9.3 miles (15 kilometers) per year to 34.2 miles (55 kilometers) per year, Dr. Arnaud Chulliat, a senior research scientist at the University of Colorado, Boulder, and the NOAA National Centers for Environmental Information, told CNN in January. Around 2015, the drift slowed to about 21.7 miles (35 kilometers) per year.
Scientists expect that the drift toward Russia will continue to slow, though there is some uncertainty about how long the slowdown will persist.
Geochemist Mengran Du had 30 minutes left on the clock of her submersible dive into a deep ocean trench that lies between Russia and Alaska when she began to notice what she called “amazing creatures,” including various species of clam and tube worm that had never been recorded at such extreme depths.
Du and her team had stumbled upon the deepest known ecosystem of organisms that use the chemical compound methane instead of sunlight to survive. The creatures live 5,800 to 9,500 meters (19,000 to 30,000 feet) below the ocean’s surface in what’s called the hadal zone.
The scientists hypothesized that microbes living in the ecosystem convert organic matter in the sediments into carbon dioxide, and carbon dioxide into methane — something the researchers didn’t know microbes could do.
The bacteria living inside clam and tube worm species then use this methane for chemosynthesis to survive, said Du, who was named by the scientific publisher Nature as one of 10 individuals who shaped 2025’s most influential science.
Earth has a lot going on under the surface.
Scientists discovered that the remnants of supercontinents hidden deep within the mantle, the large zone beneath the planet’s thin crust, are older than previously thought.
The finding from a January study suggests that the rocky mantle isn’t as uniformly blended by Earth’s internal churning as once believed. In fact, there are many hidden structures, such as these ancient tectonic plates, that may shape activity in the mantle and on Earth’s crust in ways yet to be understood.
In August, scientists revealed that another geological anomaly in the mantle — a mass of hot rock that sits about 124 miles (200 kilometers) beneath the Appalachian Mountains range in New England — was formed about 80 million years ago when Greenland and North America split apart.
The hot rock blob could help explain why ancient mountains such as the Appalachians haven’t eroded away as much as expected over time.
The remarkable discoveries of 2025 went even deeper — into Earth’s innermost layer, which is a hot, solid ball of metal, with a radius of about 759 miles (1,221 kilometers), surrounded by a liquid metal outer core.
Direct observation of Earth’s core is impossible, and scientists typically study it by analyzing changes in the size and shape of seismic waves as they pass through the core.
Scientists in 2024 confirmed that Earth’s inner core reversed its spin, and in February 2025 the same team revealed changes to the inner core’s shape, with deformations in its shallowest level.
Gold is one of the metals believed to make up the core, and in May a study based on a Hawaiian rock formation suggested that at least a tiny amount of gold has escaped to the surface.
That leaking raises a fascinating prospect: If it continues, more of this precious metal could travel from the center of Earth to the crust in the future.
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