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The Earth is ancient and immense, yet it hides countless microscopic elements that have accumulated over eons. With today's advanced technology, we can explore incredible views of minuscule details that either remain from past cataclysmic events or are vital to the smooth functioning of the planet today.
10. A Snapshot of the Solar System’s Beginnings
This is a thin slice of a meteorite that’s over four-and-a-half billion years old. The spherical objects, known as chondrules, give these meteorites their name, chondrites. Today, chondrites provide scientists with valuable insights into the formation of Earth and the rest of the solar system.
Chondrites are essentially older than dirt. They originated when the solar system was just a cloud of cosmic dust, some of which melted into chondrules. The rest of the dust began to clump together into larger objects, gaining more gravity as they grew. This process spiraled out of control and culminated when the cloud’s core ignited to form a star—our Sun. The remnants of this dust and chondrules eventually became planets, moons, asteroids, and comets.
After this, all the planets and most moons were large enough to evolve independently. Their original material no longer exists for scientists to study, making chondrites like the one shown above crucial for understanding early solar system history.
Asteroids and a few other bodies were too small to continue evolving, so they remained in the solar system for billions of years, occasionally breaking apart and falling to Earth. Today, scientists know that the bright chondrules in the image are embedded in material from the original interstellar dust cloud, which is seen as black in the picture, offering a glimpse of the process that led to the formation of our solar system.
9. Potential Ingredients for Life in Space
This blurry, out-of-focus image is a real-life depiction of the chemical structures you may have seen in textbooks. Captured with a fascinating tool called the “noncontact atomic force microscope,” it reveals carbon and hydrogen atoms bonding to form three benzene rings.
Astrobiologists are fond of the six-sided benzene ring because it can be rearranged into various molecules likely to exist in space, particularly polycyclic aromatic hydrocarbons (PAHs). These carbon-based organic molecules make up nearly half of the dust and gas clouds drifting between the stars.
Since life on Earth is carbon-based, some wonder if it could have originated from these interstellar organic molecules. While the answer remains uncertain, NASA researchers have made an intriguing discovery while studying PAHs. They exposed pyrimidine, a substance similar to PAHs, to conditions replicating the harsh environment of space. The outcome: the creation of uracil, cytosine, and thymine—three compounds found in the genetic material of all life on Earth.
One day, experts will unravel the mystery of how life on Earth first emerged. What we do know is that once life began, it underwent a series of catastrophic extinctions. Perhaps the most devastating extinction event was caused by a tiny organism named...
8. Cyanobacteria: The Microbes That First Filled Earth's Atmosphere With Oxygen
This image is exactly what it appears to be: a group of bacterial cells viewed through a microscope. Once known as blue-green algae, this organism is now referred to as cyanobacteria. The first remarkable feature of these cells is their age—they are one billion years old. Scientists uncovered them from ancient geologic formations in Australia, where they found 29 other species as well.
How can bacteria leave fossils? Cyanobacteria are larger than most bacteria and possess thick cell walls. They form mats that accumulate into layered formations known as stromatolites and oncolites. Ancient stromatolites, when sliced into extremely thin sections, sometimes reveal preserved cyanobacteria, as seen in this micrograph.
An even more remarkable fact is that without these cyanobacteria and many others like them, life as we know it wouldn’t exist today. In its early days, Earth's atmosphere resembled the smoggy air on Titan, Saturn's moon. It was inhospitable to modern life, but certain microbes, including cyanobacteria, thrived. Then, around 2.3 billion years ago, cyanobacteria evolved the ability to harness sunlight through photosynthesis. A byproduct of photosynthesis is oxygen, which was toxic to the microbes accustomed to smog. Due to their sheer numbers, cyanobacteria triggered the Great Oxygenation Event, transforming Earth’s atmosphere and likely causing one of the planet’s greatest mass extinctions. However, it also paved the way for the animals and plants that exist today.
It’s currently only speculated that cyanobacteria were responsible for eliminating the smog-loving organisms, but what we do know is that a cataclysmic event known as the Great Dying occurred, during which nearly all life on Earth perished. One of the causes behind that extinction was . . .
7. The Siberian Traps
This is what geologists refer to as a thin section—essentially a very fine slice of rock. When viewed under a microscope with polarized light, you can identify various minerals by their colors. (And by the way, thin sections also make for fantastic rock art!)
Here, we see a thin section of leucocratic gabbro. The white areas of the image represent plagioclase, while the blue parts are amphibole. Take note of how the minerals are grouped together, as if they were caught in a slow-moving flow of dark material, resembling Hawaiian lava moving from left to right.
This material was once flowing like Hawaiian-style lava, and it began pouring out of the ground in what is now Siberia around 250 million years ago. The eruption of the Siberian Traps took place during the Permian Period, coinciding with Earth’s largest known mass extinction. The flood of basalt lasted for a million years, and geologists estimate that it would have been enough lava to bury Europe under more than 1 kilometer (0.6 miles) of rock.
The consequences for life on Earth were dire. While other factors likely contributed to the Great Dying, the volcanic ash and fumes blocked sunlight, and toxic gases from the lava polluted both the air and the seas. During this period, an estimated 93–97 percent of all life was wiped out.
Some believe that the flood was triggered by a mantle plume, while others suggest it was linked to plate tectonics. The Siberian lava isn’t giving us any clues; its long-forgotten crystals simply lie there, shimmering back at us.
Earth is constantly cycling through life and death. Some of this cycle is etched into the rocks, but what about the atmosphere? Does it leave a record, or does it vanish without a trace?
6. Earth’s Atmosphere 420,000 Years Ago
These small pockets of air aren't floating through water. Instead, they are trapped in ancient ice that has been frozen for hundreds of thousands of years. By studying the air inside these bubbles, scientists gain valuable insights into Earth's past climate, how it has shifted over time, and what might happen in the future.
How does air get trapped in the ice, and how do scientists determine its age? As snowflakes fall to Earth, they capture air. If the snow doesn't melt, it becomes glacial ice with air bubbles. Everything stays in the same vertical alignment. While glaciers can move horizontally as they flow, their inner structure remains unchanged. This allows scientists to estimate the age of different horizontal layers without relying on carbon dating—the newest layers are always on top. That’s why experts know that the air trapped in ice cores from Antarctica and Greenland could be as old as 420,000 years.
The level of carbon dioxide in the atmosphere is a significant factor influencing the climate. This is a major concern today, but fortunately, a tiny marine creature is helping to mitigate the problem.
5. A Major Carbon Recycler
This isn't a satellite photo of a forest with a road winding around it. It's actually a microscopic image of Alteromonas, a recently discovered bacterium that plays a crucial role in controlling carbon dioxide (CO2) levels.
Carbon is present everywhere on Earth. It exists in the air, maintained in a delicate balance that the oceans help regulate. Seawater both absorbs and releases atmospheric CO2. Plankton consume the carbon absorbed by the ocean, and when they die, their bodies sink into the deep ocean where bacteria break them down. These bacteria then release CO2, which eventually reenters Earth's atmosphere.
At least, that’s the prevailing theory. Most of this process occurs deep beneath the ocean's surface, far beyond the reach of researchers. It was previously believed that numerous bacteria were involved in the process. However, a recent discovery has shown that a single strain of Alteromonas consumes as much carbon as an entire ecosystem of other organisms. This discovery simplifies the task for scientists when creating models of the ocean's carbon cycle. Now, they can base their calculations on the 'Fat Albert' of the sea.
4. Nine-Million-Year-Old Plants
Plants are essential in maintaining the breathability of our atmosphere. The fragments shown here were flash-fossilized during a meteorite strike millions of years ago. At the time, scientists were unaware that organic material could survive such intense heat. This breakthrough suggests that life on Mars, if it ever existed, could have been preserved in a similar way.
Here’s how it unfolded: Seven distinct space objects impacted what is now Argentina, with the final strike occurring roughly nine million years ago. The land was covered by loess, a fine, powdery soil that melted and quickly transformed into glass. After several attempts, experts discovered that when temperatures exceed 1,480 degrees Celsius (2,700 °F), the water in a plant's outer layers absorbs sufficient heat to shield its fragile inner components. This is similar to the process of deep-frying food.
Mars is similarly coated in loess and features numerous impact craters. While the planet has not had rivers or oceans for billions of years, it once did. It’s conceivable that life could have existed there, and it's entirely possible that ancient Martian life may have been preserved in impact glass, just as these plants on Earth were.
3. Endoliths
To explain these fascinating green formations, let the experts weigh in: “Twisted mineral stalks produced by iron-oxidizing bacteria retrieved from mineral incubation experiments conducted in the Juan de Fuca boreholes.”
The key term here is “boreholes.” Scientists drilled into the seafloor and discovered bacteria thriving in these depths. These tiny rock-dwelling organisms, known as endoliths, have previously been hidden from view. Living within rocks and feeding on them, endoliths have been known to scientists for some time, but only now are we realizing just how many of these creatures might be living on Earth.
The majority of Earth’s surface is covered by oceanic crust. This seafloor consists of basalt lava that erupts at mid-ocean ridges and then slowly moves away from these ridges like a natural geological conveyor belt. With abundant water and heat—two essential elements for life—it's no wonder that aquatic life thrives at hydrothermal vents along these ridges. So, why couldn’t life flourish beneath the seafloor as well?
Now, imagine this oceanic crust being teeming with life. The scientists who captured this image of green endolith stalks believe that the seafloor could indeed serve as an ideal habitat for such organisms. Some even suggest that the seafloor might harbor more biomass than all of Earth’s land and marine life combined!
2. Humans Taming Fire
This is exactly what it appears to be. The tan material is dirt, the lighter particles are ash from a wood fire, and the dark gray substance is plant matter that has been partially charred. The astonishing thing is that this provides evidence that humans controlled fire one million years ago—much earlier than expected.
The exact timeline for when humans tamed fire has always been uncertain. It’s difficult to distinguish whether the ancient layers of ash were caused by a wildfire or a cooking fire. A few years ago, scientists applied advanced methods to analyze these ashes, including those shown above. The ash came from a one-million-year-old fire discovered in a South African cave. It was untouched by natural causes, and nearby, stone tools were also found.
Here, we see the ashen remnants of a plant that someone, possibly Homo erectus, carried into that cave a million years ago. They likely weren’t vegetarians, as burned bones were also uncovered.
Mastery over fire was humanity’s greatest step towards becoming the dominant force on Earth that we are today. But are we truly the masters? Scientists are beginning to recognize that the largest collection of living organisms on Earth might actually exist in the rocky crust beneath the oceans. These tiny creatures are known as . . .
1. A Freeze-Frame Of The World’s Largest Recent Volcanic Eruption
At first glance, this might resemble a close-up of Van Gogh’s Starry Night, but it is actually a geologic thin section of volcanic rock. Rather than smears, you'll see sharp edges, indicating a violent eruption—not a slow-moving, Hawaiian-style lava flow.
The larger pieces here are clasts—broken mineral fragments. These fragments are embedded in pulverized rock that flows around them. If you look closely, you’ll notice dark voids in the powdered stone, stretching out like hot taffy being pulled.
This fragment comes from the Toba supereruption that occurred around 75,000 years ago. It was Earth’s largest known eruption in human history, releasing 2,900 cubic kilometers (700 mi) of magma and three trillion kilograms (6.6 trillion lb) of sulfur into the atmosphere. Mineral crystals shattered into clasts as they were blasted out of the vent, and moments later, they became embedded in hot, gassy volcanic ash. The gas quickly dissipated, leaving spaces within the ash particles that appear black under polarized light. Thousands of years later, geologists are still in awe of the Toba eruption's violence. Ash from the eruption traveled as far as Eastern Africa, a distance of 7,000 kilometers (4,300 mi).
